SC28L91A1A [NXP]
3.3V-5.0V Universal Asynchronous Receiver/Transmitter (UART); 3.3V - 5.0V通用异步接收器/发送器（ UART ）
| 型号： | SC28L91A1A |
| 厂家： | 
NXP |
| 描述： | 3.3V-5.0V Universal Asynchronous Receiver/Transmitter (UART) |
| 文件： | 总42页 (文件大小：271K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
INTEGRATED CIRCUITS
SC28L91
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
Product specification
2000 Sep 22
Supersedes data of 2000 Apr 03
Philips
Semiconductors
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
DESCRIPTION
• 16-bit programmable Counter/Timer
The SC28L91 is a new member of the IMPACT family of Serial
Communications Controllers. It is a single channel UART operating
at 3.3 and 5.0 volts Vcc, 8 or 16 byte FIFOs and is quite compatible
with software of the SC28L92 and previous UARTs offered by
Philips. It is a new part that is similar to our previous one channel
part but is vastly improved. The improvements being: 16 character
receiver, 16 character transmit FIFOs, watch dog timer for the
receiver, mode register 0 is added, extended baud rate, over all
faster bus and data speeds, programmable receiver and transmitter
interrupts and versatile I/O structure. (The previous one channel
part, SCC2691, is NOT being discontinued.)
• Programmable baud rate for each receiver and transmitter
selectable from:
– 28 fixed rates: 50 to 230.4 k baud
– Other baud rates to 1 MHz at 16X
– Programmable user-defined rates derived from a programmable
counter/timer
– External 1X or 16X clock
• Parity, framing, and overrun error detection
• False start bit detection
Pin programming will allow the device to operate with either the
Motorola or Intel bus interface. Bit 3 of the MR0 register allows the
device to operate in an 8-byte FIFO mode if strict compliance with
an 8-byte FIFO structure is required.
• Line break detection and generation
• Programmable channel mode
– Normal (full-duplex)
The Philips Semiconductors SC28L91 Universal Asynchronous
Receiver/Transmitter (UART) is a single-chip CMOS-LSI
communications device that provides a full-duplex asynchronous
receiver/transmitter channel in a single package. It interfaces
directly with microprocessors and may be used in a polled or
interrupt driven system with modem and DMA interface.
– Automatic echo
– Local loop back
– Remote loop back
– Multi-drop mode (also called ‘wake-up’ or ‘9-bit’)
• Multi-function 7-bit input port (includes IACKN)
– Can serve as clock or control inputs
The operating mode and data format of the channel can be
programmed independently. Additionally, the receiver and
– Change of state detection on four inputs
– Inputs have typically >100k pull-up resistors
– Change of state detectors for modem control
transmitter can select its operating speed as one of 28 fixed baud
rates; a 16X clock derived from a programmable counter/timer, or an
external 1X or 16X clock. The baud rate generator and counter/timer
can operate directly from a crystal or from external clock inputs. The
ability to independently program the operating speed of the receiver
and transmitter make the UART particularly attractive for dual-speed
channel applications such as clustered terminal systems.
• Multi-function 8-bit output port
– Individual bit set/reset capability
– Outputs can be programmed to be status/interrupt signals
– FIFO status for DMA interface
The receiver and transmitter is buffered by 8 or 16 character FIFOs
to minimize the potential of receiver overrun, transmitter underrun
and to reduce interrupt overhead in interrupt driven systems. In
addition, a flow control capability is provided via RTS/CTS signaling
to disable a remote transmitter when the receiver buffer is full.
• Versatile interrupt system
– Single interrupt output with eight maskable interrupting
conditions
– Output port can be configured to provide a total of up to six
DMA interface is and other general purpose signals are provided on
the SC28L91 via a multipurpose 7-bit input port and a multipurpose
8-bit output port. These can be used as general-purpose ports or
can be assigned specific functions (such as clock inputs or
separate interrupt outputs that may be wire ORed.
– Each FIFO can be programmed for four different interrupt levels
– Watch dog timer for the receiver
status/interrupt outputs, FIFO conditions) under program control.
• Maximum data transfer rates:
1X – 1Mb/sec, 16X – 1Mb/sec
The SC28L91 is available in two package versions: a 44-pin PLCC
and 44-pin plastic quad flat pack (PQFP).
• Automatic wake-up mode for multi-drop applications
• Start-end break interrupt/status with mid-character break detect.
• On-chip crystal oscillator
FEATURES
• Member of IMPACT family: 3.3 to 5.0 volt , –40°C to +85°C and
• Power down mode
68K for 80xxx bus interface for all devices.
• Receiver time-out mode
• A full-duplex independent asynchronous receiver/transmitter
• 16 character FIFOs for each receiver and transmitter
• Pin programming selects 68K or 80xxx-bus interface
• Single +3.3V or +5V power supply
• Programmable data format
– 5 to 8 data bits plus parity
– Odd, even, no parity or force parity
– – 1, 1.5 or 2 stop bits programmable in 1/16-bit increments
2
2000 Sep 22
853-2219 24638
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
ORDERING INORMATION
Industrial
= +3.3 ±10%, +5V ±10%
V
CC
Description
T
= –40 to +85°C
Drawing Number
SOT187-2
amb
44-Pin Plastic Leaded Chip Carrier (PLCC)
44-Pin Plastic Quad Flat Pack (PQFP)
SC28L91A1A
SC28L91A1B
SOT307-2
3
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
PIN CONFIGURATION DIAGRAM
80XXX PIN CONFIGURATION
44
34
6
40
1
7
39
1
33
23
PLCC
PQFP
11
29
17
18
28
12
Pin Function
22
Pin Function
Pin Function
Pin Function
Pin Function
Pin Function
1
2
A3
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
GND
GND
INTRN
D6
31
32
33
34
35
36
37
38
39
40
41
42
43
44
x2
1
2
NC
A0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
OP5
OP7
D1
31
32
33
34
35
36
37
38
39
40
41
42
43
44
OP2
OP0
TxDA
NC
IP0
RESET
CEN
IP2
3
WRN
RDN
3
IP3
A1
4
4
D3
5
V
D4
IP6
CC
5
IP1
A2
D5
RxDA
X1/CLK
X2
6
No Connection
D2
IP5
6
D7
7
OP1
OP3
OP5
OP7
I/M
D0
IP4
7
A3
V
SS
8
NC
V
V
CC
8
IP0
WRN
RDN
NC
RESET
CEN
IP2
9
OP6
OP4
OP2
OP0
TxDA
RxDA
x1/clk
CC
9
INTRN
D6
10
11
12
13
14
15
A0
IP3
A1
IP1
A2
10
11
12
13
14
15
V
D4
IP6
CC
D1
I/M
D2
IP5
D3
No Connection
OP1
D0
IP4
D5
OP6
OP4
V
CC
D7
OP3
SD00699
SD00698
Note: Pins marked “No Connection” must NOT be connected.
4
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
PIN CONFIGURATION DIAGRAM
68XXX PIN CONFIGURATION
44
34
6
40
1
7
39
1
33
23
PLCC
PQFP
11
29
17
18
28
12
Pin Function
22
Pin Function
Pin Function
Pin Function
Pin Function
Pin Function
1
2
A3
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
GND
GND
INTRN
D6
31
32
33
34
35
36
37
38
39
40
41
42
43
44
x2
1
2
NC
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
OP5
OP7
D1
31
32
33
34
35
36
37
38
39
40
41
42
43
44
OP2
IP0
RESETN
CEN
IP2
A0
OP0
3
R/WN
DACKN
3
IP3
TxDA
NC
4
4
A1
D3
5
V
D4
IACKN
IP5
CC
5
IP1
D5
RxDA
X1/CLK
X2
6
No Connection
D2
6
A2
D7
7
OP1
OP3
OP5
OP7
I/M
D0
IP4
7
A3
V
SS
8
NC
V
V
CC
8
IP0
NC
RESETN
CEN
IP2
9
OP6
OP4
OP2
OP0
TxDA
RxDA
x1/clk
CC
9
R/WN
DACKN
INTRN
D6
10
11
12
13
14
15
A0
IP3
A1
IP1
A2
10
11
12
13
14
15
V
D4
IACKN
IP5
CC
D1
I/M
D2
D3
No Connection
OP1
D0
IP4
D5
OP6
OP4
V
CC
D7
OP3
SD00701
SD00700
Note: Pins marked “No Connection” must NOT be connected.
5
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
8
DATA CHANNEL
D0–D7
RDN
BUS BUFFER
16 BYTE TRANSMIT
FIFO
TxDA
RxDA
TRANSMIT
SHIFT REGISTER
OPERATION CONTROL
16 BYTE RECEIVE
FIFO
WRN
CEN
ADDRESS
DECODE
WATCH DOG TIMER
4
A0–A3
RESET
RECEIVE SHIFT
REGISTER
R/W CONTROL
MRA0, 1, 2
CRA
SRA
INTERRUPT CONTROL
IMR
INTRN
ISR
GP
INPUT PORT
CHANGE OF
STATE
DETECTORS (4)
TIMING
7
IP0-IP6
BAUD RATE
GENERATOR
IPCR
ACR
CLOCK
SELECTORS
COUNTER/
TIMER
OUTPUT PORT
FUNCTION
SELECT LOGIC
8
OP0-OP7
X1/CLK
X2
XTAL OSC
OPCR
OPR
CSR
ACR
CTL
CTU
V
V
CC
SS
SD00702
Figure 1. Block Diagram (80XXX mode)
6
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
8
DATA CHANNEL
D0–D7
BUS BUFFER
16 BYTE TRANSMIT
FIFO
TxDA
RxDA
TRANSMIT
SHIFT REGISTER
OPERATION CONTROL
R/WN
16 BYTE RECEIVE
FIFO
IACKN
CEN
ADDRESS
DECODE
WATCH DOG TIMER
4
A0–A3
RESETN
RECEIVE SHIFT
REGISTER
R/W CONTROL
MRA0, 1, 2
CRA
SRA
INTERRUPT CONTROL
IMR
INTRN
ISR
IVR
DACKN
INPUT PORT
CHANGE OF
STATE
DETECTORS (4)
TIMING
6
IP0-IP5
BAUD RATE
GENERATOR
IPCR
ACR
CLOCK
SELECTORS
COUNTER/
TIMER
OUTPUT PORT
FUNCTION
SELECT LOGIC
8
OP0-OP7
X1/CLK
X2
XTAL OSC
OPCR
OPR
CSR
ACR
CTL
CTU
V
V
CC
SS
SD00703
Figure 2. Block Diagram (68XXX mode)
7
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
PIN CONFIGURATION FOR 80XXX BUS INTERFACE (INTEL )
Pin
type
Symbol
I/M
Name and function
I
Bus Configuration: When high or not connected configures the bus interface to the Conditions shown in this table.
D0–D7
I/O
Data Bus: Bi-directional 3-State data bus used to transfer commands, data and status between the UART and the
CPU. D0 is the least significant bit.
CEN
I
Chip Enable: Active-Low input signal. When Low, data transfers between the CPU and the UART are enabled on
D0–D7 as controlled by the WRN, RDN and A0–A3 inputs. When High, places the D0–D7 lines in the 3-State condi-
tion.
WRN
RDN
I
I
Write Strobe: When Low and CEN is also Low, the contents of the data bus is loaded into the addressed register. The
transfer occurs on the rising edge of the signal.
Read Strobe: When Low and CEN is also Low, causes the contents of the addressed register to be presented on the
data bus. The read cycle begins on the falling edge of RDN.
A0–A3
I
I
Address Inputs: Select the UART internal registers and ports for read/write operations.
RESET
Reset: A High level clears internal registers (SR, IMR, ISR, OPR, OPCR), puts OP0–OP7 in the High state, stops the
counter/timer, and puts the Channel in the inactive state, with the TxD outputs in the mark (High) state. Sets MR point-
er to MR1. See Figure 4
INTRN
X1/CLK
X2
O
I
Interrupt Request: Active-Low, open-drain, output which signals the CPU that one or more of the eight maskable in-
terrupting conditions are true. This pin requires a pull-up device.
Crystal 1: Crystal or external clock input. A crystal or clock of the specified limits must be supplied at all times. When a
crystal is used, a capacitor must be connected from this pin to ground (see Figure 11).
O
Crystal 2: Connection for other side of the crystal. When a crystal is used, a capacitor must be connected from this pin
to ground (see Figure 11). If X1/CLK is driven from an external source, this pin must be left open.
RxD
TxD
I
Receiver Serial Data Input: The least significant bit is received first. “Mark” is High; “space” is Low.
O
Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in the “mark” condition
when the transmitter is disabled, idle or operating in local loop back mode. “Mark” is High; “space” is Low.
OP0
O
Output 0: General-purpose output or request to send (RTSN, active-Low). Can be deactivated automatically on re-
ceive or transmit.
OP1
OP2
OP3
OP4
OP5
OP6
OP7
IP0
O
O
O
O
O
O
O
I
Output 1: General-purpose output.
Output 2: General-purpose output, or transmitter 1X or 16X clock output, or receiver 1X clock output.
Output 3: General-purpose output.
Output 4: General-purpose output or open-drain, active-Low, Rx interrupt ISR[1] output. DMA Control
Output 5: General-purpose output
Output 6: General-purpose output or open-drain, active-Low, Tx interrupt ISR[0] output. DMA Control
Output 7: General-purpose output.
Input 0: General-purpose input or clear to send active-Low input (CTSN). Has Change of State Dector.
Input 1: General-purpose input. Has Change of State Dector.
IP1
I
IP2
I
Input 2: General-purpose input or counter/timer external clock input. Has Change of State Dector.
IP3
I
Input 3: General-purpose input or transmitter external clock input (TxC). When the external clock is used by the trans-
mitter, the transmitted data is clocked on the falling edge of the clock. Has Change of State Dector.
IP4
I
Input 4: General-purpose input or receiver external clock input (RxC). When the external clock is used by the receiver,
the received data is sampled on the rising edge of the clock.
IP5
IP6
I
Input 5: General-purpose input
Input 6: General-purpose input
Power Supply: +3.3 or +5V supply input ±10%
Ground
I
V
CC
Pwr
Pwr
GND
8
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
PIN CONFIGURATION FOR 68XXX BUS INTERFACE (MOTOROLA )
Pin
type
Symbol
I/M
Name and function
I
Bus Configuration: When low configures the bus interface to the Conditions shown in this table.
D0–D7
I/O
Data Bus: Bi-directional 3-State data bus used to transfer commands, data and status between the UART and the
CPU. D0 is the least significant bit.
CEN
I
Chip Enable: Active-Low input signal. When Low, data transfers between the CPU and the UART are enabled on
D0–D7 as controlled by the R/WN and A0–A3 inputs. When High, places the D0–D7 lines in the 3-State condition.
R/WN
I
I
Read/Write: Input Signal. When CEN is low R/WN high input indicates a read cycle; when low indicates a write cycle.
IACKN
Interrupt Acknowledge: Active low input indicating an interrupt acknowledge cycle. Usually asserted by the CPU in
response to an interrupt request. When asserted places the interrupt vector on the bus and asserts DACKN.
DACKN
O
Data Transfer Acknowledge: A3-State active-low output asserted in a write, read, or interrupt acknowledge cycle to
indicate proper transfer of data between the CPU and the UART.
A0–A3
I
I
Address Inputs: Select the UART internal registers and ports for read/write operations.
RESETN
Reset: A low level clears internal registers (SRA, SRB, IMR, ISR, OPR, OPCR), puts OP0–OP7 in the High state,
stops the counter/timer, and puts the Channel in the inactive state, with the TxD outputs in the mark (High) state. Sets
MR pointer to MR1. See Figure 4
INTRN
X1/CLK
X2
O
I
Interrupt Request: Active-Low, open-drain, output which signals the CPU that one or more of the eight maskable
interrupting conditions are true. This pin requires a pullup.
Crystal 1: Crystal or external clock input. A crystal or clock of the specified limits must be supplied at all times. When
a crystal is used, a capacitor must be connected from this pin to ground (see Figure 11).
O
Crystal 2: Connection for other side of the crystal. When a crystal is used, a capacitor must be connected from this
pin to ground (see Figure 11). If X1/CLK is driven from an external source, this pin must be left open.
RxD
TxD
I
Receiver Serial Data Input: The least significant bit is received first. “Mark” is High, “space” is Low.
O
Transmitter Serial Data Output: The least significant bit is transmitted first. This output is held in the ‘mark’ condition
when the transmitter is disabled, idle, or when operating in local loop back mode. ‘Mark’ is High; ‘space’ is Low.
OP0
O
Output 0: General purpose output or request to send (RTSAN, active-Low). Can be deactivated automatically on
receive or transmit.
OP1
OP2
OP3
OP4
OP5
OP6
OP7
IP0
O
O
O
O
O
O
O
I
Output 1: General-purpose output.
Output 2: General purpose output or transmitter 1X or 16X clock output, or receiver 1X clock output.
Output 3: General purpose output.
Output 4: General purpose output or open-drain, active-Low, RxA interrupt ISR [1] output. DMA Control
Output 5: General-purpose output.
Output 6: General purpose output or open-drain, active-Low, TxA interrupt ISR[0] output. DMA Control
Output 7: General-purpose output.
Input 0: General purpose input or clear to send active-Low input (CTSAN). Has Change of State Dector.
Input 1: General purpose input. Has Change of State Dector.
IP1
I
IP2
I
Input 2: General-purpose input or counter/timer external clock input. Has Change of State Dector.
IP3
I
Input 3: General purpose input or transmitter external clock input (TxC). When the external clock is used by the trans-
mitter, the transmitted data is clocked on the falling edge of the clock. Has Change of State Dector.
IP4
I
Input 4: General purpose input or receiver external clock input (RxC). When the external clock is used by the receiver,
the received data is sampled on the rising edge of the clock.
IP5
I
Input 5: General purpose input.
Power Supply: +3.3 or +5V supply input ±10%
Ground
V
CC
Pwr
Pwr
GND
9
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
1
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Rating
Unit
°C
2
T
amb
Operating ambient temperature range
Note 4
T
Storage temperature range
–65 to +150
–0.5 to +7.0
°C
stg
3
V
V
P
P
Voltage from V to GND
V
CC
CC
3
Voltage from any pin to GND
–0.5 to V +0.5
V
S
CC
Package power dissipation (PLCC44)
Package power dissipation (PQFP44)
2.4
1.78
19
W
D
W
D
Derating factor above 25°C (PLCC44)
Derating factor above 25°C (PQFP44)
mW/°C
mW/°C
14
NOTES:
1. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or any other condition above those indicated in the operation section of this specification is not
implied.
2. For operating at elevated temperatures, the device must be derated based on +150°C maximum junction temperature.
3. This product includes circuitry specifically designed for the protection of its internal devices from damaging effects of excessive static
charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying any voltages larger than the rated maxima.
4. Parameters are valid over specified temperature and voltage range.
1, 2, 3
DC ELECTRICAL CHARACTERISTICS
V
= 5V ± 10%, T
= –40°C to +85°C, unless otherwise specified.
CC
amb
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
V
V
V
V
V
Input low voltage
0.8
IL
Input high voltage (except X1/CLK)
Input high voltage (X1/CLK)
Output low voltage
2.4
1.5
2.4
0.2
V
IH
IH
OL
0.8*V
V
CC
0.4
V
I
I
= 2.4mA
= -400µA
= 0 to V
OL
4
V
I
Output high voltage (except OD outputs)
V
CC
-0.5
V
OH
OH
X1/CLK input current - power down
X1/CLK input low current - operating
X1/CLK input high current - operating
Input leakage current:
0.5
0.05
0.5
0
µA
µA
µA
V
V
V
IX1PD
IN
IN
IN
CC
I
I
= 0
= V
–130
0
ILX1
130
IHX1
CC
All except input port pins
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
= 0 to V
= 0 to V
–0.5
–8
0.05
0.05
+0.5
+0.5
0.5
µA
µA
µA
µA
µA
µA
I
CC
CC
I
5
Input port pins
I
I
I
I
Output off current high, 3-State data bus
Output off current low, 3-State data bus
= V
CC
OZH
OZL
ODL
ODH
= 0V
= 0
–0.5
–0.5
Open-drain output low current in off-state
Open-drain output high current in off-state
= V
0.5
CC
6
Power supply current
Operating mode
CMOS input levels
CMOS input levels
7
25
5
mA
I
CC
Power down mode
≤1
mA
NOTES:
1. Parameters are valid over specified temperature and voltage range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5ns maximum. For X1/CLK, this swing is between 0.4 V and 0.8*V . All time measurements are referenced at input voltages of 0.8V and
CC
2.0V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Typical values are at +25°C, typical supply voltages, and typical processing parameters.
4. Test conditions for outputs: C = 125 pF, except open drain outputs. Test conditions for open drain outputs: C = 125 pF,
L
L
constant current source = 2.6 mA.
5. Input port pins have active pull-up transistors that will source a typical 2 µA from V when the input pins are at V
.
SS
CC
Input port pins at V source 0.0 µA.
CC
6. All outputs are disconnected. Inputs are switching between CMOS levels of V -0.2 V and V + 0.2 V.
CC
SS
10
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
1, 2, 3
DC ELECTRICAL CHARACTERISTICS
V
= 3.3V ± 10%, T
= –40°C to +85°C, unless otherwise specified.
CC
amb
Symbol
Parameter
Conditions
Min
Typ
0.65
1.7
Max
Unit
V
V
V
V
Input low voltage
Input high voltage
Output low voltage
0.2*V
IL
CC
0.8*V
V
IH
OL
CC
0.2
0.4
V
I
I
= 2.4mA
= –400µA
= 0 to V
OL
4
V
I
Output high voltage (except OD outputs)
V
CC
–0.5
V –0.2
CC
V
OH
OH
X1/CLK input current - power down
X1/CLK input low current - operating
X1/CLK input high current - operating
Input leakage current:
–0.5
–80
0
0.05
+0.5
0
µA
µA
µA
V
V
V
IX1PD
IN
IN
IN
CC
I
I
= 0
= V
ILX1
80
IHX1
CC
All except input port pins
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
= 0 to V
= 0 to V
–0.5
–8
0.05
0.5
+0.5
+0.5
0.5
µA
µA
µA
µA
µA
µA
I
CC
CC
I
5
Input port pins
I
I
I
I
Output off current high, 3-State data bus
Output off current low, 3-State data bus
= V
CC
OZH
OZL
ODL
ODH
= 0V
= 0
–0.5
–0.5
Open-drain output low current in off-state
Open-drain output high current in off-state
= V
0.5
CC
6
Power supply current
Operating mode
CMOS input levels
CMOS input levels
5
mA
I
CC
Power down mode
≤1
5.0
mA
NOTES:
1. Parameters are valid over specified temperature and voltage range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5ns maximum. For X1/CLK, this swing is between 0.4 V and 0.8*V . All time measurements are referenced at input voltages of 0.8 V and
CC
2.0V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Typical values are at +25°C, typical supply voltages, and typical processing parameters.
4. Test conditions for outputs: C = 125 pF, except open drain outputs. Test conditions for open drain outputs: C = 125 pF,
L
L
constant current source = 2.6 mA.
5. Input port pins have active pull-up transistors that will source a typical 2 µA from V when the input pins are at V
.
SS
CC
Input port pins at V source 0.0 µA.
CC
6. All outputs are disconnected. Inputs are switching between CMOS levels of V –0.2 V and V +0.2 V.
CC
SS
11
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
1, 2, 3, 4
AC CHARACTERISTICS (5 VOLT)
V
= 5.0V ± 10%, T
= –40°C to +85°C, unless otherwise specified.
CC
amb
Symbol
Reset Timing (See Figure 4)
Reset pulse width
Parameter
Min
Typ
Max
Unit
t
100
18
ns
RES
5
Bus Timing (See Figure 5)
t
t
t
t
t
t
t
t
t
t
t
t
A0–A3 setup time to RDN, WRN Low
10
20
0
6
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
*AS
*AH
*CS
*CH
*RW
*DD
*DA
*DF
*DI
A0–A3 hold time from RDN, WRN low
12
CEN setup time to RDN, WRN low
CEN Hold time from RDN. WRN low
0
WRN, RDN pulse width (Low time)
15
8
Data valid after RDN low (125pF load. See Figure 3 for smaller loads.)
40
55
20
6
RDN low to data bus active
0
Data bus floating after RDN or CEN high
7
RDN or CEN high to data bus invalid
0
Data bus setup time before WRN or CEN high (write cycle)
Data hold time after WRN high
25
0
17
*DS
*DH
*RWD
–12
10
5, 7
High time between read and/or write cycles
15
5
Port Timing (See Figure 9)
t
t
t
Port in setup time before RDN low (Read IP ports cycle)
Port in hold time after RDN high
0
0
–20
–20
40
ns
ns
ns
*PS
*PH
*PD
OP port valid after WRN or CEN high (OPR write cycle)
60
Interrupt Timing (See Figure 10)
INTRN (or OP3–OP7 when used as interrupts) negated from:
t
*IR
Read RxFIFO (RxRDY/FFULL interrupt)
Write TxFIFO (TxRDY interrupt)
40
40
40
40
40
40
60
60
60
60
60
60
ns
ns
ns
ns
ns
ns
Reset Command (delta break change interrupt)
Stop C/T command (Counter/timer interrupt
Read IPCR (delta input port change interrupt)
Write IMR (Clear of change interrupt mask bit(s))
Clock Timing (See Figure 11)
t
f
f
f
t
f
X1/CLK high or low time
30
0.1
30
0
20
ns
*CLK
*CLK
*CTC
*CTC
*RX
8
X1/CLK frequency (for higher speeds contact factory)
3.686 8.0
MHz
ns
C/T Clk (IP2) high or low time (C/T external clock input)
10
8.0
10
16
1
8
C/T Clk (IP2) frequency (for higher speeds contact factory)
MHz
ns
RxC high or low time (16X)
30
0
RxC Frequency (16X)(for higher speeds contact factory)
MHz
MHz
ns
*RX
8, 9
RxC Frequency (1x)
0
t
f
TxC High or low time (16X)
30
10
16
1
*TX
TxC frequency (16X) (for higher speeds contact factory)
MHz
MHz
*TX
8, 9
TxC frequency (1X)
0
Transmitter Timing, external clock (See Figure 12)
t
TxD output delay from TxC low (TxC input pin)
40
6
60
30
ns
ns
*TXD
*TCS
t
Output delay from TxC output pin low to TxD data output
12
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
Symbol
Parameter
Min
Typ
Max
Unit
Receiver Timing, external clock (See Figure 13)
t
t
RxD data setup time to RxC high
RxD data hold time from RxC high
50
50
40
40
ns
ns
*RXS
*RXH
10
68000 or Motorola bus timing (See Figures 6, 7, 8)
10
t
t
t
t
DACKN Low (read cycle) from X1 High
15
15
8
20
20
10
ns
ns
ns
ns
DCR
DCW
DAT
DACKN Low (write cycle) from X1 High
DACKN High impedance from CEN or IACKN High
CEN or IACKN setup time to X1 High for minimum DACKN cycle
10
8
CSC
NOTES:
1. Parameters are valid over specified temperature and voltage range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/CLK this swing is between 0.4 V and 0.8*V . All time measurements are referenced at input voltages of 0.8 V and
CC
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Test conditions for outputs: CL = 125 pF, except open drain outputs. Test conditions for open drain outputs: C = 125 pF,
L
constant current source = 2.6 mA.
4. Typical values are the average values at +25°C and 5 V.
5. Timing is illustrated and referenced to the WRN and RDN Inputs. Also, CEN may be the “strobing” input. CEN and RDN (also CEN and
WRN) are ORed internally. The signal asserted last initiates the cycle and the signal negated first terminates the cycle.
6. Guaranteed by characterization of sample units.
7. If CEN is used as the “strobing” input, the parameter defines the minimum High times between one CEN and the next. The RDN signal must
be negated for t
to guarantee that any status register changes are valid.
RWD
8. Minimum frequencies are not tested but are guaranteed by design.
9. Clocks for 1X mode should maintain a 60/40 duty cycle or better.
10.Minimum DACKN time is t
= t
+ t
+ two positive edges of the X1 clock. For faster bus cycles, the 80XXX bus timing may be used
DCR
DSC
DCR
while in the 68XXX mode. It is not necessary to wait for DACKN to insure the proper operation of the SC28C91. In all cases the data will be
written to the SC28L91 on the falling edge of DACKN or the rise of CEN. The fall of CEN initializes the bus cycle. The rise of CEN ends the
bus cycle. DACKN low or CEN high completes the write cycle.
60
V
= 3.3V @ +25°C
CC
55
50
45
40
35
30
25
20
15
10
5
5.0V @ +25°C
T
dd
(ns)
12 pF
30 pF
100 pF
100
125 pF
230 pF
0
0
20
40
60
80
120
pF
140
160
180
200
220
240
SD00684
NOTES:
Bus cycle times:
(80XXX mode): t + t
= 70 ns @ 5V, 40 ns @ 3.3 V + rise and fall time of control signals
RWD
DD
(68XXX mode) = t
+ t
+ 1 cycle of the X1 clock @ 5 V + rise and fall time of control signals
CSC
DAT
Figure 3. Port Timing vs. Capacitive Loading at typical conditions
13
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
1, 2, 3, 4
AC CHARACTERISTICS (3.3 VOLT)
V
= 3.3V ± 10%, T
= –40°C to +85°C, unless otherwise specified.
CC
amb
Symbol
Reset Timing (See Figure 4)
Reset pulse width
Parameter
Min
Typ
Max
Unit
t
100
20
ns
RES
5
Bus Timing (See Figure 5)
t
t
t
t
t
t
t
t
t
t
t
t
A0–A3 setup time to RDN, WRN Low
10
25
0
6
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
*AS
*AH
*CS
*CH
*RW
*DD
*DA
*DF
*DI
A0–A3 hold time from RDN, WRN low
16
CEN setup time to RDN, WRN low
CEN Hold time from RDN. WRN low
0
WRN, RDN pulse width (Low time)
20
10
46
Data valid after RDN low (125pF load. See Figure 3 for smaller loads.)
75
20
6
RDN low to data bus active
0
Data bus floating after RDN or CEN high
15
7
RDN or CEN high to data bus invalid
0
Data bus setup time before WRN or CEN high (write cycle)
Data hold time after WRN high
25
0
20
*DS
*DH
*RWD
–15
10
5, 7
High time between read and/or write cycles
20
5
Port Timing (See Figure 9)
t
t
t
Port in setup time before RDN low (Read IP ports cycle)
Port in hold time after RDN high
0
0
–20
–20
50
ns
ns
ns
*PS
*PH
*PD
OP port valid after WRN or CEN high (OPR write cycle)
70
Interrupt Timing (See Figure 10)
INTRN (or OP3–OP7 when used as interrupts) negated from:
t
*IR
Read RxFIFO (RxRDY/FFULL interrupt)
Write TxFIFO (TxRDY interrupt)
40
40
40
40
40
40
60
60
60
60
60
60
ns
ns
ns
ns
ns
ns
Reset Command (delta break change interrupt)
Stop C/T command (Counter/timer interrupt)
Read IPCR (delta input port change interrupt)
Write IMR (Clear of change interrupt mask bit(s))
Clock Timing (See Figure 11)
t
f
f
f
t
f
X1/CLK high or low time
30
0.1
30
0
25
ns
*CLK
*CLK
*CTC
*CTC
*RX
8
X1/CLK frequency (for higher speeds contact factory)
3.686
15
8
8
MHz
ns
C/T Clk (IP2) high or low time (C/T external clock input)
8
C/T Clk (IP2) frequency (for higher speeds contact factory)
MHz
ns
RxC high or low time (16X)
30
0
10
15
RxC Frequency (16X) (for higher speeds contact factory)
16
1
MHz
MHz
ns
*RX
8, 9
RxC Frequency (1x)
0
t
f
TxC High or low time (16X)
30
*TX
TxC frequency (16X) (for higher speeds contact factory)
16
1
MHz
MHz
*TX
8, 9
TxC frequency (1X)
0
Transmitter Timing, external clock (See Figure 12)
t
TxD output delay from TxC low (TxC input pin)
40
8
60
30
ns
ns
*TXD
*TCS
t
Output delay from TxC output pin low to TxD data output
14
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
Symbol
Parameter
Min
Typ
Max
Unit
Receiver Timing, external clock (See Figure 13)
t
t
RxD data setup time to RxC high
RxD data hold time from RxC high
50
50
10
10
ns
ns
*RXS
*RXH
10
68000 or Motorola bus timing (See Figures 6, 7, 8)
10
t
t
t
t
DACKN Low (read cycle) from X1 High
18
18
10
10
25
25
15
ns
ns
ns
ns
DCR
DCW
DAT
DACKN Low (write cycle) from X1 High
DACKN High impedance from CEN or IACKN High
CEN or IACKN setup time to X1 High for minimum DACKN cycle
15
CSC
NOTES:
1. Parameters are valid over specified temperature and voltage range.
2. All voltage measurements are referenced to ground (GND). For testing, all inputs swing between 0.4 V and 3.0 V with a transition time of
5 ns maximum. For X1/CLK this swing is between 0.4 V and 0.8*V . All time measurements are referenced at input voltages of 0.8 V and
CC
2.0 V and output voltages of 0.8 V and 2.0 V, as appropriate.
3. Test conditions for outputs: CL = 125 pF, except open drain outputs. Test conditions for open drain outputs: C = 125 pF,
L
constant current source = 2.6 mA.
4. Typical values are the average values at +25°C and 3.3 V.
5. Timing is illustrated and referenced to the WRN and RDN Inputs. Also, CEN may be the “strobing” input. CEN and RDN (also CEN and
WRN) are ORed internally. The signal asserted last initiates the cycle and the signal negated first terminates the cycle.
6. Guaranteed by characterization of sample units.
7. If CEN is used as the “strobing” input, the parameter defines the minimum High times between one CEN and the next. The RDN signal must
be negated for t
to guarantee that any status register changes are valid.
RWD
8. Minimum frequencies are not tested but are guaranteed by design.
9. Clocks for 1X mode should maintain a 60/40 duty cycle or better.
10.Minimum DACKN time is t
= t
+ t
+ two positive edges of the X1 clock. For faster bus cycles, the 80XXX bus timing may be used
DCR
DSC
DCR
while in the 68XXX mode. It is not necessary to wait for DACKN to insure the proper operation of the SC28C91. In all cases the data will be
written to the SC28L91 on the falling edge of DACKN or the rise of CEN. The fall of CEN initializes the bus cycle. The rise of CEN ends the
bus cycle. DACKN low or CEN high completes the write cycle.
15
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
Block Diagram
TIMING CIRCUITS
Crystal Clock
The SC28L91 UART consists of the following seven major sections:
data bus buffer, operation control, interrupt control, timing, Rx and
Tx FIFO Buffers, input port and output port control. Refer to the
Block Diagram.
The timing block consists of a crystal oscillator, a baud rate
generator, a programmable 16-bit counter/timer, and four clock
selectors. The crystal oscillator operates directly from a crystal
connected across the X1/CLK and X2 inputs. If an external clock of
the appropriate frequency is available, it may be connected to
X1/CLK. The clock serves as the basic timing reference for the Baud
Rate Generator (BRG), the counter/timer, and other internal circuits.
A clock signal within the limits specified in the specifications section
of this data sheet must always be supplied to the UART. If an
external clock is used instead of a crystal, X1 should be driven using
a configuration similar to the one in Figure 11. X2 should be open or
driving a nominal gate load. Nominal crystal rate is 3.6864 MHz.
Rates up to 8 MHz may be used.
Data Bus Buffer
The data bus buffer provides the interface between the external and
internal data buses. It is controlled by the operation control block to
allow read and write operations to take place between the controlling
CPU and the UART.
Operation Control
The operation control logic receives operation commands from the
CPU and generates appropriate signals to internal sections to
control device operation. It contains address decoding and read and
write circuits to permit communications with the microprocessor via
the data bus.
BRG
The baud rate generator operates from the oscillator or external
clock input and is capable of generating 28 commonly used data
communications baud rates ranging from 50 to 38.4 K baud.
Programming bit 0 of MR0 to a “1” gives additional baud rates of
57.6 kB, 115.2 kB and 230.4 kB (500 kHz with X1 at 8.0 MHz).
These will be in the 16X mode. A 3.6864 MHz crystal or external
clock must be used to get the standard baud rates. The clock
outputs from the BRG are at 16X the actual baud rate. The
counter/timer can be used as a timer to produce a 16X clock for any
other baud rate by counting down the crystal clock or an external
clock. The four clock selectors allow the independent selection, for
the receiver and transmitter, of any of these baud rates or external
timing signal.
Interrupt Control
A single active-Low interrupt output (INTRN) is provided which is
activated upon the occurrence of any of eight internal events.
Associated with the interrupt system are the Interrupt Mask Register
(IMR) and the Interrupt Status Register (ISR). The IMR can be
programmed to select only certain conditions to cause INTRN to be
asserted. The ISR can be read by the CPU to determine all currently
active interrupting conditions. Outputs OP3–OP7 can be
programmed to provide discrete interrupt outputs for the transmitter,
receiver, and counter/timer. Programming the OP3 to OP7 pins as
interrupts causes their output buffers to change to an open drain
active low configuration. The OP pins may be used for DMA and
modem control as well. (See output port notes).
Counter/Timer
FIFO Configuration
The counter timer is a 16-bit programmable divider that operates in
one of three modes: counter, timer, and time out. In the timer mode it
generates a square wave. In the counter mode it generates a time
delay. In the time out mode it monitors the time between received
characters. The C/T uses the numbers loaded into the
Counter/Timer Lower Register (CTLR) and the Counter/Timer Upper
Register (CTUR) as its divisor.
Each receiver and transmitter has a 16 byte FIFO. These FIFOs
may be configured to operate at a fill capacity of either 8 or 16 bytes.
This feature may be used if it is desired to operate the 28L91 in
close compliance to 26C92 software. The 8-byte/16-byte mode is
controlled by the MR0[3] bit. A 0 value for this bit sets the 8-bit mode
( the default); a 1 sets the 16-byte mode.
The FIFO fill interrupt level automatically follow the programming of
the MR0[3] bit. See Tables 3 and 4.
The counter/timer clock source and mode of operation (counter or
timer) is selected by the Auxiliary Control Register bits 6 to 4
(ACR[6:4]). The output of the counter/timer may be used for a baud
rate and/or may be output to the OP pins for some external function
that may be totally unrelated to data transmission. The counter/timer
also sets the counter/timer ready bit in the Interrupt Status Register
(ISR) when its output transitions from 1 to 0. A register read address
(see Table 1) is reserved to issue a start counter/timer command
and a second register read address is reserved to issue a stop
command. The value of D[7:0] is ignored. The START command
always loads the contents of CTUR, CTLR to the counting registers.
The STOP command always resets the ISR[3] bit in the interrupt
status register.
68XXX mode
When the I/M pin is connected to V (ground), the operation of the
SS
SC28L91 switches to the bus interface compatible with the Motorola
bus interfaces. Several of the pins change their function as follows:
• IP6 becomes IACKN input
• RDN becomes DACKN
• WRN becomes R/WN
The interrupt vector is enabled and the interrupt vector will be placed
on the data bus when IACKN is asserted low. The interrupt vector
register is located at address 0xC. The contents of this register are
set to 0x0F on the application of RESETN.
Timer Mode
In the timer mode a symmetrical square wave is generated whose
half period is equal in time to division of the selected counter/timer
clock frequency by the 16-bit number loaded in the CTLR CTUR.
Thus, the frequency of the counter/timer output will be equal to the
counter/timer clock frequency divided by twice the value of the
CTUR CTLR. While in the timer mode the ISR bit 3 (ISR[3]) will be
set each time the counter/timer transitions from 1 to 0. (High to low)
The generation of DACKN uses two positive edges of the X1 clock
as the DACKN delay from the falling edge of CEN. If the CEN is
withdrawn before two edges of the X1 clock occur, the
generation of DACKN is terminated. Systems not strictly requiring
DACKN may use the 68XXX mode with the bus timing of the 80XXX
mode greatly decreasing the bus cycle time.
16
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
This continues regardless of issuance of the stop counter command.
ISR[3] is reset by the stop counter command.
ISR [3], and the interrupt. Invoking the ‘Set Timeout Mode On’
command, CRx = 0xAn, will also clear the counter ready bit and stop
the counter until the next character is received. The counter timer is
controlled with six commands: Start/Stop C/T, Read/Write
Counter/Timer lower register and Read/Write Counter/Timer upper
register. These commands have slight differences depending on the
mode of operation. Please see the detail of the commands under the
CTLR CTUR Register descriptions.
NOTE: Reading of the CTU and CTL registers in the timer mode is
not meaningful. When the C/T is used to generate a baud rate and
the C/T is selected through the CSR then the receiver and/or
transmitter will be operating in the 16x mode. Calculation for the
number ‘n’ to program the counter timer upper and lower registers is
shown below.
Time Out Mode Caution
cńt clock rate
When operating in the special time out mode it is possible to
generate what appears to be a “false interrupt”, i.e. an interrupt
without a cause. This may result when a time-out interrupt occurs
and then, BEFORE the interrupt is serviced, another character is
received, i.e., the data stream has started again. (The interrupt
latency is longer than the pause in the data stream.) In this case,
when a new character has been receiver, the counter/timer will be
restarted by the receiver, thereby withdrawing its interrupt. If, at this
time, the interrupt service begins for the previously seen interrupt, a
read of the ISR will show the “Counter Ready” bit not set. If nothing
else is interrupting, this read of the ISR will return a x’00 character.
This action may present the appearance of a spurious interrupt.
N +
2 * 16 * Baud rate
Often this division will result in a non-integer number; 26.3 for
example. One can only program integer numbers to a digital divider.
Therefore 26 would be chosen. This gives a baud rate error of
0.3/26.3 which is 1.14%; well within the ability of the asynchronous
mode of operation.
Counter Mode
In the counter mode the counter/timer counts the value of the CTLR
CTUR down to zero and then sets the ISR[3] bit and sets the
counter/timer output from 1 to 0. It then rolls over to 65,365 and
continues counting with no further observable effect. Reading the
C/T in the counter mode outputs the present state of the C/T. If the
C/T is not stopped, a read of the C/T may result in changing data on
the data bus.
Communications
The communications channel of the SC28L91 comprises a
full-duplex asynchronous receiver/transmitter (UART). The operating
frequency for the receiver and transmitter can be selected
independently from the baud rate generator, the counter/timer, or
from an external input. The transmitter accepts parallel data from the
CPU, converts it to a serial bit stream, inserts the appropriate start,
stop, and optional parity bits and outputs a composite serial stream
of data on the TxD output pin. The receiver accepts serial data on
the RxD pin, converts this serial input to parallel format, checks for
start bit, stop bit, parity bit (if any), or break condition and sends an
assembled character to the CPU via the receive FIFO. Three status
bits (Break Received, Framing and Parity Errors) are also FIFOed
with the data character.
Timeout Mode
The timeout mode uses the received data stream to control the
counter. The time-out mode forces the C/T into the timer mode.
Each time a received character is transferred from the shift register
to the RxFIFO, the counter is restarted. If a new character is not
received before the counter reaches zero count, the counter ready
bit is set, and an interrupt can be generated. This mode can be used
to indicate when data has been left in the Rx FIFO for more than the
programmed time limit. If the receiver has been programmed to
interrupt the CPU when the receive FIFO is full, and the message
ends before the FIFO is full, the CPU will not be interrupted for the
remaining characters in the RxFIFO.
Input Port
The inputs to this unlatched 7-bit (6-bit for 68xxx mode) port can be
read by the CPU by performing a read operation at address 0xD. A
High input results in a logic 1 while a Low input results in a logic 0.
D7 will always read as a logic 1. The pins of this port can also serve
as auxiliary inputs to certain portions of the UART logic, modem and
DMA.
By programming the C/T such that it would time out in just over one
character time, the above situation could be avoided. The processor
would be interrupted any time the data stream had stopped for more
than one character time. NOTE: This is very similar to the watch dog
timer of MR0. The difference is in the programmability of the delay
timer and that this indicates that the data stream has stopped. The
watchdog timer is more of an indicator that data is in the FIFO is not
enough to cause an interrupt. The watchdog is restarted by either a
receiver load to the RxFIFO or a system read from it.
Four change-of-state detectors are provided which are associated
with inputs IP3, IP2, IP1 and IP0. A High-to-Low or Low-to-High
transition of these inputs, lasting longer than 25–50 s, will set the
corresponding bit in the input port change register. The bits are
cleared when the register is read by the CPU. Any change-of-state
can also be programmed to generate an interrupt to the CPU.
This mode is enabled by writing the appropriate command to the
command register. Writing an ‘0xAn’ to CR will invoke the timeout
mode for that channel. Writing a ‘Cx’ to CR will disable the timeout
mode. The timeout mode disables the regular START/STOP counter
commands and puts the C/T into counter mode under the control of
the received data stream. Each time a received character is
transferred from the shift register to the RxFIFO, the C/T is stopped
after one C/T clock, reloaded with the value in CTUR and CTLR and
then restarted on the next C/T clock. If the C/T is allowed to end the
count before a new character has been received, the counter ready
Bit, ISR[3], will be set. If IMR [3] is set, this will generate an interrupt.
Since receiving a character restarts the C/T, the receipt of a
The input port change of state detection circuitry uses a 38.4 kHz
sampling clock derived from one of the baud rate generator taps.
This results in a sampling period of slightly more than 25 s (this
assumes that the clock input is 3.6864 MHz). The detection circuitry,
in order to guarantee that a true change in level has occurred,
requires two successive samples at the new logic level be observed.
As a consequence, the minimum duration of the signal change is
25 s if the transition occurs “coincident with the first sample pulse”.
The 50 s time refers to the situation in which the change-of-state is
character after the C/T has timed out will clear the counter ready bit,
17
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
“just missed” and the first change-of-state is not detected until 25
later.
s
If CTS option is enabled (MR2[4] = 1), the CTS input at IP0 or IP1
must be Low in order for the character to be transmitted. The
transmitter will check the state of the CTS input at the beginning of
the character transmitted. If it is found to be High, the transmitter will
delay the transmission of any following characters until the CTS has
returned to the low state. CTS going high during the serialization of
a character will not affect that character.
Output Port
The output ports are controlled from six places: the OPCR, OPR,
MR, Command, SOPR and ROPR registers. The OPCR register
controls the source of the data for the output ports OP2 through
OP7. The data source for output ports OP0 and OP1 is controlled by
the MR and CR registers. When the OPR is the source of the data
for the output ports, the data at the ports is inverted from that in the
OPR register. The content of the OPR register is controlled by the
“Set Output Port Bits Command” and the “Reset Output Bits
Command”. These commands are at E and F, respectively. When
these commands are used, action takes place only at the bit
locations where ones exist. For example, a one in bit location 5 of
the data word used with the “Set Output Port bits” command will
result in OPR[5] being set to one. The OP5 would then be set to
The transmitter can also control the RTSN outputs, OP0 or OP1 via
MR2[5]. When this mode of operation is set, the meaning of the OP0
or OP1 signals will usually be ‘end of message’. See description of
the MR2[5] bit for more detail. This feature may be used to
automatically “turn around” a transceiver in simplex systems.
Receiver
The SC28L91 is conditioned to receive data when enabled through
the command register. The receiver looks for a High-to-Low
(mark-to-space) transition of the start bit on the RxD input pin. If a
transition is detected, the state of the RxD pin is sampled the 16X
clock for 7–1/2 clocks (16X clock mode) or at the next rising edge of
the bit time clock (1X clock mode). If RxD is sampled high, the start
bit is invalid and the search for a valid start bit begins again. If RxD
is still Low, a valid start bit is assumed and the receiver continues to
sample the input at one-bit time intervals at the theoretical center of
the bit. When the proper number of data bits and parity bit (if any)
have been assembled, and one/half stop bit has been detected the
byte is loaded to the RxFIFO. The least significant bit is received
first. The data is then transferred to the Receive FIFO and the
RxRDY bit in the SR is set to a 1. This condition can be
programmed to generate an interrupt at OP4 or OP5 and INTRN. If
the character length is less than 8 bits, the most significant unused
bits in the RxFIFO are set to zero.
zero (V ). Similarly, a one in bit position 5 of the data word
SS
associated with the “Reset Output Ports Bits” command would set
OPR[5] to zero and, hence, the pin OP5 to a one (V ).
DD
These pins along with the IP pins and their change of state detectors
are often used for modem and DMA control.
OPERATION
Transmitter
The SC28L91 is conditioned to transmit data when the transmitter is
enabled through the command register. The SC28L91 indicates to
the CPU that it is ready to accept a character by setting the TxRDY
bit in the status register. This condition can be programmed to
generate an interrupt request at OP6 or OP7 and INTRN. When the
transmitter is initially enabled the TxRDY and TxEMPT bits will be
set in the status register. When a character is loaded to the transmit
FIFO the TxEMPT bit will be reset. The TxEMPT will not set until: 1)
the transmit FIFO is empty and the transmit shift register has
finished transmitting the stop bit of the last character written to the
transmit FIFO, or 2) the transmitter is disabled and then re-enabled.
The TxRDY bit is set whenever the transmitter is enabled and the
TxFIFO is not full. Data is transferred from the holding register to
transmit shift register when it is idle or has completed transmission
of the previous character. Characters cannot be loaded into the
TxFIFO while the transmitter is disabled.
After the stop bit is detected, the receiver will immediately look for
the next start bit. However if a framing error occurs (a non-zero
character was received without a stop bit) and then RxD remains
low one/half bit time the receiver operates as if a new start bit was
detected. It then continues to assemble the next character.
The parity error, framing error, and overrun error (if any) are strobed
into the SR from the next byte to be read from the Rx FIFO.
If a break condition is detected (RxD is Low for the entire character
including the stop bit), a character consisting of all zeros will be
loaded into the RxFIFO and the received break bit in the SR is set to
1. The RxD input must return to high for two (2) clock edges of the
X1 crystal clock for the receiver to recognize the end of the break
condition and begin the search for a start bit.
The transmitter converts the parallel data from the CPU to a serial
bit stream on the TxD output pin. It automatically sends a start bit
followed by the programmed number of data bits, an optional parity
bit, and the programmed number of stop bits. The least significant
bit is sent first. Following the transmission of the stop bits, if a new
character is not available in the TxFIFO, the TxD output remains
High and the TxEMT bit in the Status Register (SR) will be set to 1.
Transmission resumes and the TxEMT bit is cleared when the CPU
loads a new character into the TxFIFO.
This will usually require a high time of one X1 clock period or 3 X1
edges since the clock of the controller is not synchronous to the X1
clock.
Transmitter Reset and Disable
Note the difference between transmitter disable and reset. A
transmitter reset stops transmitter action immediately, clears the
transmitter FIFO and returns the idle state. A transmitter disable
withdraws the transmitter interrupts but allows the transmitter to
continue operation until all bytes in its FIFO and shift register have
been transmitted including the final stop bits. It then returns to its
idle state.
If the transmitter is disabled it continues operating until the character
currently being transmitted and any characters in the TxFIFO,
including parity and stop bits, have been transmitted. New data
cannot be loaded to the TxFIFO when the transmitter is disabled.
When the transmitter is reset it stops sending data immediately.
Receiver FIFO
The transmitter can be forced to send a break (a continuous low
condition) by issuing a START BREAK command via the CR
register. The break is terminated by a STOP BREAK command or a
transmitter reset.
The RxFIFO consists of a First-In-First-Out (FIFO) stack with a
capacity of 8 or 16 characters. Data is loaded from the receive shift
register into the topmost empty position of the FIFO. The RxRDY bit
18
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
in the status register is set whenever one or more characters are
available to be read, and a FFULL status bit is set if all 8 or 16 stack
positions are filled with data. Either of these bits can be selected to
cause an interrupt. A read of the RxFIFO outputs the data at the top
of the FIFO. After the read cycle, the data FIFO and its associated
status bits (see below) are ‘popped’ thus emptying a FIFO position
for new data.
read. This situation may occur at the end of a transmission when the
last few characters received are not sufficient to cause an interrupt.
This counter times out after 64 bit times. It is reset each time a
character is transferred from the receiver shift register to the
RxFIFO or a read of the RxFIFO is executed.
Receiver Time-out Mode
In addition to the watch dog timer described in the receiver section,
the counter/timer may be used for a similar function. Its 16-bit
programmability allows much greater precision of time out intervals.
A disabled receiver with data in its FIFO may generate an interrupt
(see “Receiver Status Bits”, below). Its status bits remain active and
its watchdog, if enabled, will continue to operate.
The time-out mode uses the received data stream to control the
counter. Each time a received character is transferred from the shift
register to the RxFIFO, the counter is restarted. If a new character is
not received before the counter reaches zero count, the counter
ready bit is set, and an interrupt can be generated. This mode can
be used to indicate when data has been left in the RxFIFO for more
than the programmed time limit. Otherwise, if the receiver has been
programmed to interrupt the CPU when the receive FIFO is full, and
the message ends before the FIFO is full, the CPU may not know
there is data left in the FIFO. The CTU and CTL value would be
programmed for just over one character time, so that the CPU would
be interrupted as soon as it has stopped receiving continuous data.
This mode can also be used to indicate when the serial line has
been marking for longer than the programmed time limit. In this
case, the CPU has read all of the characters from the FIFO, but the
last character received has started the count. If there is no new data
during the programmed time interval, the counter ready bit will get
set, and an interrupt can be generated.
Receiver Status Bits
In addition to the data word, three status bits (parity error, framing
error, and received break) are also appended to the data character
in the FIFO. The overrun error, MR1[5], and the change of break
(ISR[2]) are not FIFOed.
The status of the Rx FIFO may be provided in two ways, as
programmed by the error mode control bit in the mode register
(MR1[5]). In the ‘character’ mode, status is provided on a
character-by-character basis; the status applies only to the
character at the top of the FIFO. In the ‘block’ mode, the status
provided in the SR for these three bits is the logical-OR of the status
for all characters coming to the top of the FIFO since the last ‘reset
error’ from the command register was issued. In either mode
reading the SR does not affect the FIFO. The FIFO is ‘popped’ only
when the RxFIFO is read. Therefore the status register should be
read prior to reading the FIFO.
If the FIFO is full when a new character is received, that character is
held in the receive shift register until a FIFO position is available. If
an additional character is received while this state exits, the
contents of the FIFO are not affected; the character previously in the
shift register is lost and the overrun error status bit (SR[4]) will be
set-upon receipt of the start bit of the new (overrunning) character.
The time-out mode is enabled by writing the appropriate command
to the command register. Writing an 0xAn to CR will invoke the
time-out mode for that channel. Writing a ‘Cx’ to CR will disable the
time-out mode. The time-out mode should only be used by one
channel at once, since it uses the C/T. CTU and CTL must be
loaded with a value greater than the normal receive character
period. The time-out mode disables the regular START/STOP
Counter commands and puts the C/T into counter mode under the
control of the received data stream. Each time a received character
is transferred from the shift register to the RxFIFO, the C/T is
stopped after 1 C/T clock, reloaded with the value in CTU and CTL
and then restarted on the next C/T clock. If the C/T is allowed to end
the count before a new character has been received, the counter
ready bit, ISR[3], will be set. If IMR[3] is set, this will generate an
interrupt. Receiving a character after the C/T has timed out will clear
the counter ready bit, ISR[3], and the interrupt. Invoking the ‘Set
Time-out Mode On’ command, CRx = ‘Ax’, will also clear the counter
ready bit and stop the counter until the next character is received.
The receiver can control the deactivation of RTS. If programmed to
operate in this mode, the RTSN output will be negated when a valid
start bit was received and the FIFO is full. When a FIFO position
becomes available, the RTSN output will be re-asserted (set low)
automatically. This feature can be used to prevent an overrun, in the
receiver, by connecting the RTSN output to the CTSN input of the
transmitting device.
If the receiver is disabled, the FIFO characters can be read.
However, no additional characters can be received until the receiver
is enabled again. If the receiver is reset, the FIFO and all of the
receiver status, and the corresponding output ports and interrupt are
reset. No additional characters can be received until the receiver is
enabled again.
Watchdog and Time Out Mode Differences
The watchdog timer is restarted each time a character is read from
or written to the Rx FIFO. It is an indicator that data is in the FIFO
that has not been read. If the Rx FIFO is empty no action occurs. In
the time out mode the C/T is stopped and restarted each time a
character is written to the Rx FIFO. From this point of view the time
out of the C/T is an indication that the data stream has stopped.
After the time out mode is invoked the timer will not start until the
first character is written to the Rx FIFO.
Receiver Reset and Disable
Receiver disable stops the receiver immediately—data being
assembled in the receiver shift register is lost. Data and status in the
FIFO is preserved and may be read. A re-enable of the receiver
after a disable will cause the receiver to begin assembling
characters at the next start bit detected.
A receiver reset will discard the present shift register date, reset the
receiver ready bit (RxRDY), clear the status of the byte at the top of
the FIFO and re-align the FIFO read/write pointers.
Time Out Mode Caution
When operating in the special time out mode, it is possible to
generate what appears to be a “false interrupt”, i.e. an interrupt
without a cause. This may result when a time-out interrupt occurs
and then, BEFORE the interrupt is serviced, another character is
received, i.e., the data stream has started again. (The interrupt
Watchdog
A ‘watchdog timer’ is associated with the receiver. Its interrupt is
enabled by MR0[7]. The purpose of this timer is to alert the control
processor that characters are in the RxFIFO which have not been
19
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
latency is longer than the pause in the data stream.) In this case,
when a new character has been received, the counter/timer will be
restarted by the receiver, thereby withdrawing its interrupt. If, at this
time, the interrupt service begins for the previously seen interrupt, a
read of the ISR will show the “Counter Ready” bit not set. If nothing
else is interrupting, this read of the ISR will return a x’00 character.
character if the received A/D bit is a zero (data tag). If enabled, all
received characters are transferred to the CPU via the RxFIFO. In
either case, the data bits are loaded into the data FIFO while the
A/D bit is loaded into the status FIFO position normally used for
parity error (SR[5] ). Framing error, overrun error, and break detect
operate normally whether or not the receiver is enabled.
Multi-drop Mode (9-bit or Wake-Up)
The UART is equipped with a wake up mode for multi-drop
applications. This mode is selected by programming bits MR1[4:3]or
to ‘11’. In this mode of operation, a ‘master’ station transmits an
address character followed by data characters for the addressed
‘slave’ station. The slave station(s) whose receiver(s) that are
normally disabled, examine the received data stream and ‘wakeup’
the CPU (by setting RxRDY) only upon receipt of an address
character. The CPU compares the received address to its station
address and enables the receiver if it wishes to receive the
subsequent data characters. Upon receipt of another address
character, the CPU may disable the receiver to initiate the process
again.
PROGRAMMING
The operation of the UART is programmed by writing control words
into the appropriate registers. Operational feedback is provided via
status registers which can be read by the CPU. The addressing of
the registers is described in Table 1.
The contents of certain control registers are initialized to zero on
RESET. Care should be exercised if the contents of a register are
changed during operation, since certain changes may cause
operational problems.
For example, changing the number of bits per character while the
transmitter is active may cause the transmission of an incorrect
character. In general, the contents of the MR, the CSR, and the
OPCR should only be changed while the receiver(s) and
transmitter(s) are not enabled, and certain changes to the ACR
should only be made while the C/T is stopped.
A transmitted character consists of a start bit, the programmed
number of data bits, and Address/Data (A/D) bit, and the
programmed number of stop bits. The polarity of the transmitted A/D
bit is selected by the CPU by programming bit MR1[2]. MR1[2]= 0
transmits a zero in the A/D bit position, which identifies the
corresponding data bits as data. MR1[2] = 1 transmits a one in the
A/D bit position, which identifies the corresponding data bits as an
address. The CPU should program the mode register prior to
loading the corresponding data bits into the TxFIFO.
The channel has 3 mode registers (MR0, 1, 2) which control the
basic configuration of the channel. Access to these registers is
controlled by independent MR address pointers. These pointers are
set to 0 or 1 by MR control commands in the command register
“Miscellaneous Commands”. Each time the MR registers are
accessed the MR pointer increments, stopping at MR2. It remains
pointing to MR2 until set to 0 or 1 via the miscellaneous commands
of the command register. The pointer is set to 1 on reset for
compatibility with previous Philips Semiconductors UART software.
MR1[2] = 1 transmits a one in the A/D bit position, which identifies
the corresponding data bits as an address. The CPU should
program the mode register prior to loading the corresponding data
bits into the TxFIFO.
Refer to Table 2 for register bit descriptions. The reserved registers
at addresses 0x02 and 0x0A should never be read during normal
operation since they are reserved for internal diagnostics.
In this mode, the receiver continuously looks at the received data
stream, whether it is enabled or disabled. If disabled, it sets the
RxRDY status bit and loads the character into the RxFIFO if the
received A/D bit is a one (address tag), but discards the received
Table 1. SC28L91 register addressing
Address Bits
A[3:0]
READ (RDN = 0)
WRITE (WRN = 0)
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
0
0
1
1
0
0
1
1
0
0
0
1
1
0
1
0
1
0
1
0
1
0
0
1
0
1
Mode Register(MR0, MR1, MR2)
Status Register(SR)
Reserved
Mode Register(MR0, MR1, MR2)
Clock Select Register(CSR)
Command Register(CR)
Tx Holding Register(RxFIFO)
Aux. Control Register (ACR)
Interrupt Mask Register (IMR)
C/T Upper Preset Register (CTPU)
C/T Lower Preset Register (CTPL)
Interrupt vector (68K mode), Misc. register in Intel mode
IVR Motorola mode, Misc. register (Intel mode)
Output Port Configuration Register (OPCR)
Set Output Port Bits Command (SOPR)
Rx Holding Register(RxFIFO)
Input Port Change Register (IPCR)
Interrupt Status Register (ISR)
Counter/Timer Upper (CTU)
Counter/Timer Lower (CTL)
Interrupt vector (68K mode), Misc. register in Intel mode
IVR Motorola mode, Misc. register (Intel mode)
Input Port (IPR)
Start Counter Command
Stop Counter Command
Reset output Port Bits Command (ROPR)
NOTE:
1. The three MR registers are accessed via the MR Pointer and Commands 0x1n and 0xBn (where n = represents receiver and transmitter enable bits)
20
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
Register Acronyms and Read / Write Capability
(R/W = Read/Write, R = Read only, W = Write only)
Interrupt Mask Register
Counter Timer Upper Value
Counter Timer Lower Value
Counter Timer Preset Upper
Counter Timer Preset Lower
Input Port Register
Output Configuration Register
Set Output Port
Reset Output Port
IMR
CTU
CTL
CTPU
CTPL
IPR
OPCR
Bits
W
R
R
W
W
R
W
W
W
R/W
Mode Register
Status Register
MRn
SR
R/W
R
W
W
R
W
R
W
R
Clock Select
Command Register
Receiver FIFO
CSR
CR
RxFIFO
RxFIFO
IPCR
ACR
ISR
Transmitter FIFO
Input Port Change Register
Auxiliary Control Register
Interrupt Status Register
Bits
IVR/GP
Interrupt vector or GP register
Table 2. Condensed Register bit formats
Adr Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
TEST 2
Bit 0
Name
MR0
0
WATCH
RxINT BIT 2
TxINT [1:0]
FIFO SIZE
BAUD RATE
EXTENDED
II
BAUD RATE
EXTENDED 1
DOG
MR1
MR2
0
0
RxRTS
Control
RxINT BIT 1
Error Mode
Parity Mode
Parity Type
Bits per Character
Channel Mode
TxRTS Con-
trol
CTSN Enable Stop Bit Length
Tx
CSR
SR
1
1
Receiver Clock, Select Code
Transmitter Clock select code,
Received
Break
Framing Er-
ror
Parity Error
Overrun Error TxEMT
TxRDY
RxFULL
RxRDY
CR
2
3
3
4
4
5
Channel Command codes
Read 8 bits from Rx FIFO
Write 8 bits to Tx FIFO
Disable Tx
Enable Tx
Disable Rx
Enable Rx
RxFIFO
TxFIFO
IPCR
ACR
Delta IP3
Delta IP2
Delta IP1
Delta IP0
State of IP3
Enable IP3
Counter
Ready
State of IP2
Enable IP2
Change
Break
State of IP1
Enable IP1
RxRDY
State of IP0
Enable IP0
TxRDY
Baud Group Counter Timer mode and clock select
Change In- Ignore in ISR Reads
put Port
ISR
IMR
5
Change In- Set to 0
put Port
Set to 0
Set to 0
Counter
Ready
Change
Break
RxRDY
TxRDY
CTU
CTPU
CTL
CTPL
IPR
OPCR
6
6
7
7
D
D
Read 8 MSb of the BRG Timer divisor.
Write 8 MSb of the BRG Timer divisor.
Read 8 LSb of the BRG Timer divisor.
Write 8 LSb of the BRG Timer divisor.
State of IP
State of IP 6
State of IP 5
State of IP 4
State of IP 3
State of IP 2
State of IP1
State of IP 0
Configure
OP7
Configure
OP6
Configure
OP5
Configure
OP4
Configure OP3
Configure OP2
Strt C/T
SOPR
Stp C/T
ROPR
E
E
F
F
Read Address E to start Counter Timer
Set OP 7 Set OP 6 Set OP 5
Read Address F to stop counter Timer
Reset OP 7 Reset OP 6 Reset OP 5
Set OP 4
Set OP 3
Set OP 2
Set OP 1
Set OP 0
Reset OP 4
Reset OP 3
Reset OP 2
Reset OP 1
Reset OP 0
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2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
REGISTER DESCRIPTIONS MODE REGISTERS
MR0 – Mode Register 0
Mode Register 0. MR0 is accessed by setting the MR pointer to 0 via the command register command B.
Addr
MR0
Bit 7
Rx
WATCHDOG
BIT 6
RxINT BIT 2
BITS 5:4
TxINT (1:0)
BIT 3
FIFO SIZE
BIT 2
BAUD RATE
EXTENDED II
BIT 1
TEST 2
BIT 0
BAUD RATE
EXTENDED 1
0x00
0x08
0 = Disable
1 = Enable
See Tables in
MR0 descrip-
tion
See Table 4
0 = 8 byte FIFO
1 = 16 byte FIFO
0 = Normal
1 = Extend II
Set to 0
0 = Normal
1 = Extend
MR0[7]—Watchdog Control
MR0[5:4]—Tx interrupt fill level.
This bit controls the receiver watchdog timer. 0 = disable,
1 = enable. When enabled, the watch dog timer will generate a
receiver interrupt if the receiver FIFO has not been accessed within
64 bit times of the receiver 1X clock. This is used to alert the control
processor that data is in the RxFIFO that has not been read. This
situation may occur when the byte count of the last part of a
message is not large enough to generate an interrupt.
Table 4. Transmitter FIFO
Interrupt fill level MR0(3) = 0 (8 bytes)
MR0[5:4]
Interrupt Condition
00
01
10
11
8 bytes empty (Tx EMPTY)
4 or more bytes empty
6 or more bytes empty
MR0[6]—Rx Interrupt bit 2
Bit 2 of receiver FIFO interrupt level. This bit along with Bit 6 of MR1
sets the fill level of the FIFO that generates the receiver interrupt.
1 or more bytes empty (Tx RDY)
Table 4a. Transmitter FIFO
MR0[6], MR1[6] Rx Interrupt bits
Interrupt fill level MR0(3) = 1 (16 bytes)
Note that this control is split between MR0 and MR1. This is for
backward compatibility to legacy software of the SC2692 and
SCN2681 dual UART devices.
MR0[5:4]
Interrupt Condition
00
01
10
11
16 bytes empty (Tx EMPTY)
8 or more bytes empty
Table 3. Receiver FIFO
Interrupt fill level (MR0(3) = 0 (8 bytes)
12 or more bytes empty
1 or more bytes empty (Tx RDY)
MR0[6] MR1[6]
Interrupt Condition
00
01
10
11
1 or more bytes in FIFO (Rx RDY)
6 or more bytes in FIFO
4 or more bytes in FIFO
8 bytes in FIFO (Rx FULL)
For the transmitter these bits control the number of FIFO positions
empty when the transmitter will attempt to interrupt. After the reset
the transmit FIFO has 8 bytes empty. It will then attempt to interrupt
as soon as the transmitter is enabled. The default setting of the MR0
bits [5:4] condition the transmitter to attempt to interrupt only when it
is completely empty. As soon as one–byte is loaded, it is no longer
empty and hence will withdraw its interrupt request.
Table 3a. Receiver FIFO
Interrupt fill level(MR0(3)=1 (16 bytes)
MR0[6] MR1[6]
Interrupt Condition
MR0[3]—FIFO size
Selects the FIFO depth at 8 or 16 bytes. See Tables 3 and 4
00
01
10
11
1 or more bytes in FIFO (Rx RDY)
8 or more bytes in FIFO
MR0[2:0]—Baud Rate Group Selection
These bits are used to select one of the six–baud rate groups.
12 or more bytes in FIFO
16 bytes in FIFO (Rx FULL)
See Table 5 for the group organization.
• 000 Normal mode
For the receiver these bits control the number of FIFO positions
filled when the receiver will attempt to interrupt. After the reset the
receiver FIFO is empty. The default setting of these bits cause the
receiver to attempt to interrupt when it has one or more bytes in it.
• 001 Extended mode I
• 100 Extended mode II
Other combinations of MR2[2:0] should not be used.
22
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
MR1 – Mode Register 1
Addr
MR1
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BITS PER
BIT 0
Rx CONTROLS
RTS
RxINT
BIT 1
ERROR
MODE
PARITY MODE
PARITY TYPE
CHARACTER
0x00
0 = No
1 = Yes
0 = RxRDY
1 = FFULL
0 = Char
1 = Block
00 = With Parity
01 = Force Parity
10 = No Parity
0 = Even
1 = Odd
00 = 5
01 = 6
10 = 7
11 = 8
11 = Multi-drop Mode
NOTE:
In block error mode, block error conditions must be cleared by using the error reset command (command 4x) or a receiver reset.
MR1 is accessed when the MR pointer points to MR1. The pointer is
set to MR1 by RESET or by a ‘set pointer’ command applied via CR
command 0x10. After reading or writing MR1, the pointer will point to
MR2 and will not move from MR2 on subsequent MR reads or
writes.
provided on a character-by-character basis; the status applies only
to the character at the top of the FIFO. In the ‘block’ mode, the
status provided in the SR for these bits is the accumulation
(logical-OR) of the status for all characters coming to the top of the
FIFO since the last ‘reset error’ command was issued.
MR1[7]— Receiver Request–to–Send Control (Flow Control)
This bit controls the deactivation of the RTSN output (OP0) by the
receiver. This output is normally asserted by setting OPR[0] and
negated by resetting OPR[0]. Proper automatic operation of flow
control requires OPR[0] to be set to logical 1.
MR1[4:3|— Parity Mode Select
If ‘with parity’ or ‘force parity’ is selected a parity bit is added to the
transmitted character and the receiver performs a parity check on
incoming data MR1[4:3] = 11 selects operation in the special
multi–drop mode described in the Operation section.
MR1[7] = 1 causes RTSN to be negated (OP0 is driven to a ‘1’
[V ]) upon receipt of a valid start bit if the FIFO is full. This is the
CC
MR1[2]— Parity Type Select
This bit selects the parity type (odd or even) if the ‘with parity’ mode
is programmed by MR1[4:3], and the polarity of the forced parity bit
if the ‘force parity’ mode is programmed. It has no effect if the ‘no
parity’ mode is programmed. In the special multi-drop mode it
selects the polarity of the A/D bit.
beginning of the reception of the ninth byte. If the FIFO is not read
before the start of the tenth or 17th byte, an overrun condition will
occur and the tenth or 17th or 17th byte will be lost. However, the bit
in OPR[0] is not reset and RTSN will be asserted again when an
empty FIFO position is available. This feature can be used for flow
control to prevent overrun in the receiver by using the RTSN output
signal to control the CTSN input of the transmitting device.
MR1[1:0]— Bits Per Character Select
This field selects the number of data bits per character to be
transmitted and received. The character length does not include the
start, parity, and stop bits.
MR1[6]—Rx Interrupt Bit 1
Bit 1 of the receiver interrupt control. See description under MR0[6].
MR1[5]— Error Mode Select
This bit selects the operating mode of the three FIFOed status bits
(FE, PE, and received break) for. In the ‘character’ mode, status is
23
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
MR2 – Mode Register 2
MR2 is accessed when the MR pointer points to MR2, which occurs after any access to MR1. Accesses to MR2 do not change the pointer.
ADDR
MR
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
CHANNEL MODE
Tx CONTROLS
RTS
CTS
ENABLE Tx
STOP BIT LENGTH
NOTE: Add 0.5 to binary codes 0–7 for 5 bit character lengths.
0x00
00 = Normal
0 = 0.563
1 = 0.625
2 = 0.688
3 = 0.750
4 = 0.813
5 = 0.875
6 = 0.938
7 = 1.000
8 = 1.563
9 = 1.625
A = 1.688
B = 1.750
C = 1.813
D = 1.875
E = 1.938
F = 2.000
01 = Auto-Echo
10 = Local loop
11 = Remote loop
0 = No
0 = No
1 = Yes
1 = Yes
NOTE:
Add 0.5 to values shown for 0–7 if channel is programmed for 5 bits/char.
MR2[7:6]— Mode Select
4. The received parity is not checked and is not regenerated for
transmission, i.e., transmitted parity is as received.
The channel of the UART can operate in one of four modes.
MR2[7:6] = 00 is the normal mode, with the transmitter and receiver
operating independently.
5. The receiver must be enabled.
6. Character framing is not checked, and the stop bits are
retransmitted as received.
MR2[7:6] = 01 places the channel in the automatic echo mode,
which automatically retransmits the received data. The following
conditions are true while in automatic echo mode:
7. A received break is echoed as received until the next valid start
bit is detected.
1. Received data is reclocked and retransmitted on the TxD output.
2. The receive clock is used for the transmitter.
The user must exercise care when switching into and out of the
various modes. The selected mode will be activated immediately
upon mode selection, even if this occurs in the middle of a received
or transmitted character. Likewise, if a mode is deselected the
device will switch out of the mode immediately.
3. The receiver must be enabled, but the transmitter needs not be
enabled.
4. The TxRDY and TxEMT status bits are inactive.
5. The received parity is checked, but is not regenerated for
transmission, i.e. transmitted parity bit is as received.
An exception to this occurs when switching out of auto echo or
remote loop back modes. If the de-selection occurs just after the
receiver has sampled the stop bit (indicated in auto echo by
assertion of RxRDY) and the transmitter is enabled, then the
transmitter will remain in auto echo mode until the stop bit(s) have
been re-transmitted.
6. Character framing is checked, but the stop bits are retransmitted
as received.
7. A received break is echoed as received until the next valid start
bit is detected.
In most situations the above is rendered transparent by other
system considerations. However recall that the stop bit sequence
may be very long compared to bus cycles. If rapid reconfiguration of
the transmitter is desired in the above conditions the controlling
system should wait for the TxEMT bit to set or issue a Tx software
reset before reconfiguration begins.
8. CPU to receiver communication continues normally, but the CPU
to transmitter link is disabled.
MR2[7:6] = 10 selects local loop back diagnostic mode. In this
mode:
1. The transmitter output is internally connected to the receiver
input.
MR2[5]— Transmitter Request–to–Send Control
This bit controls the deactivation of the RTSN output (OP0) by the
transmitter. This output is normally asserted by setting OPR[0] and
negated by resetting OPR[0]. MR2[5] = 1 caused OPR[0] to be
reset automatically one bit time after the characters in the transmit
shift register and in the TxFIFO, if any, are completely transmitted
including the programmed number of stop bits, if the transmitter is
not enabled.
2. The transmit clock is used for the receiver.
3. The TxD output is held High.
4. The RxD input is ignored.
5. The transmitter must be enabled, but the receiver need not be
enabled.
6. CPU to transmitter and receiver communications continue
normally.
This feature can be used to automatically terminate the transmission
of a message as follows (“line turnaround”):
1. Program auto–reset mode: MR2[5] = 1.
MR2[7:6] = 11 selects remote loop back diagnostic mode. In this
2. Enable transmitter.
3. Asset RTSN: OPR[0] = 1.
4. Send message.
mode:
1. Received data is reclocked and retransmitted on the TxD
out–put.
2. The receive clock is used for the transmitter.
5. Disable transmitter after the last character is loaded into the
TxFIFO.
3. Received data is not sent to the local CPU, and the error status
conditions are inactive.
24
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
6. The last character will be transmitted and OPR[0] will be reset
one bit time after the last stop bit, causing RTSN to be negated.
MR2[3:0]— Stop Bit Length Select
This field programs the length of the stop bit appended to the
transmitted character. Stop bit lengths of 9/16 to 1 and 1–9/16 to 2
bits, in increments of 1/16 bit, can be programmed for character
lengths of 6, 7, and 8 bits. For a character lengths of 5 bits, 1–1/16
to 2 stop bits can be programmed in increments of 1/16 bit. In all
cases, the receiver only checks for a ‘mark’ condition at the center
of the stop bit position (one half-bit time after the last data bit, or
after the parity bit if enabled is sampled).
MR2[4]— Clear-to-Send Control
If this bit is 0, CTSN has no effect on the transmitter. If this bit is a 1,
the transmitter checks the state of CTSN (IP0) the time it is ready to
send a character. If IP0 is asserted (Low), the character is
transmitted. If it is negated (High), the TxD output remains in the
marking state and the transmission is delayed until CTSN goes low.
Changes in CTSN while a character is being transmitted do not
affect the transmission of that character..
If an external 1X clock is used for the transmitter, then MR2[3] = 0
selects one stop bit and MR2[3] = 1 selects two stop bits to be
transmitted.
25
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
CSR CLOCK SELECT REGISTER
Addr
CSR
0x01
CSR (7:4)
CSR (3:0)
RECEIVER CLOCK SELECT
See Text and table 5
TRANSMITTER CLOCK SELECT
See Text and table 5
Table 5. Baud rate (base on a 3.6864MHz crystal clock)
MR0[0] = 0 (Normal Mode)
MR0[0] = 1 (Extended Mode I)
MR0[2] = 1 (Extended Mode II)
CSRA[7:4]
0000
0001
0010
0011
ACR[7] = 0
50
ACR[7] = 1
75
ACR[7] = 0
300
ACR[7] = 1
450
ACR[7] = 0
4,800
ACR[7] = 1
7,200
110
110
110
110
880
880
134.5
200
134.5
150
134.5
1200
134.5
900
1,076
1,076
19.2K
28.8K
57.6K
115.2K
1,050
14.4K
28.8K
57.6K
115.2K
2,000
0100
0101
0110
300
300
1800
1800
600
600
3600
3600
1,200
1,050
2,400
4,800
7,200
9,600
38.4K
Timer
IP4–16X
IP4–1X
1,200
2,000
2,400
4,800
1,800
9,600
19.2K
Timer
IP4–16X
IP4–1X
7200
7,200
2,000
14.4K
28.8K
1,800
57.6K
115.2K
Timer
IP4–16X
IP4–1X
0111
1,050
14.4K
28.8K
7,200
57.6K
230.4K
Timer
IP4–16X
IP4–1X
1000
1001
1010
1011
57.6K
4,800
57.6K
4,800
57.6K
9,600
14.4K
9,600
1100
38.4K
Timer
19.2K
Timer
1101
1110
IP4–16X
IP4–1X
IP4–16X
IP4–1X
1111
NOTE:
1. The receiver clock is always a 16X clock except for CSR[7:4] = 1111. CSR[3:0]— Transmitter Clock Select. This field selects the baud rate
clock for the transmitter.
The field definition is as shown in Table 5, except as follows:
CSR[3:0]
1110
1111
IP3 –16X
IP3 –1X
The transmitter clock is always a 16X clock except for CSR[3:0] = 1111.
Table 6. Bit rate generator characteristics for Crystal or Clock = 3.6864MHz
NORMAL RATE (BAUD)
ACTUAL 16X CLOCK (KHz)
ERROR (%)
50
0.8
0
75
1.2
0
110
134.5
150
1.759
2.153
2.4
–0.069
0.059
0
200
3.2
0
300
4.8
0
600
9.6
0
1050
1200
1800
2000
2400
4800
7200
9600
19.2K
38.4K
16.756
19.2
28.8
32.056
38.4
76.8
115.2
153.6
307.2
614.4
–0.260
0
0
0.175
0
0
0
0
0
0
NOTE:
Duty cycle of 16X clock is 50% ꢀ1%
26
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
CR—Command Register
CR is a register used to supply commands to the UART. Multiple
commands can be specified in a single write to CR as long as the
commands are non–conflicting, e.g., the ‘enable transmitter’ and
‘reset transmitter’ commands cannot be specified in a single
command word.
CR COMMAND REGISTER
Addr
CR
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
MISCELLANEOUS COMMANDS
Disable Tx
Enable Tx
Disable Rx
Enable Rx
0x02
See Text of Channel Command Register
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
1 = Yes
0 = No
NOTES:
Access to the miscellaneous commands should be separated by 3 X1 clock edges. A disabled transmitter cannot be loaded.
CR[7:4]—Miscellaneous Commands
1011
1100
Set MR pointer to ‘0’
Execution of the commands in the upper four bits of this register
must be separated by 3 X1 clock edges. Other reads or writes
(including writes to the lower four bits) may be inserted to achieve
this separation.
Disable Timeout Mode. This command returns control
of the C/T to the regular START/STOP counter com-
mands. It does not stop the counter, or clear any pend-
ing interrupts. After disabling the timeout mode, a ‘Stop
Counter’ command should be issued to force a reset of
the ISR[3] bit
CR[7:4]—Commands
1101
1110
Not used.
0000
0001
No command.
Reset MR pointer. Causes the MR pointer to point to
MR1.
Power Down Mode On. In this mode, the UART oscilla-
tor is stopped and all functions requiring this clock are
suspended. The execution of commands other than
disable power down mode (1111) requires a X1/CLK.
While in the power down mode, do not issue any com-
mands to the CR except the disable power down mode
command. The contents of all registers will be saved
while in this mode. It is recommended that the transmit-
ter and receiver be disabled prior to placing the UART
into power down mode.
0010
Reset receiver. Resets the receiver as if a hardware
reset had been applied. The receiver is disabled and
the FIFO is flushed.
0011
0100
Reset transmitter. Resets the transmitter as if a hard-
ware reset had been applied.
Reset error status. Clears the Received Break, Parity
Error, and Overrun Error bits in the status register
(SR[7:4]). Used in character mode to clear OE status
(although Received Break, PE and FE bits will also be
cleared) and in block mode to clear all error status after
a block of data has been received.
1111
Disable Power Down Mode. This command restarts the
oscillator. After invoking this command, wait for the os-
cillator to start up before writing further commands to
the CR.
0101
0110
Reset break change interrupt. Causes the break detect
change bit in the interrupt status register (ISR[2]) to be
cleared to zero
CR[3]—Disable Transmitter
This command terminates transmitter operation and reset the
TxRDY and TxEMT status bits. However, if a character is being
transmitted or if a character is in the TxFIFO when the transmitter is
disabled, the transmission of the character(s) is completed before
assuming the inactive state.
Start break. Forces the TxD output Low (spacing). If the
transmitter is empty the start of the break condition will
be delayed up to two bit times. If the transmitter is ac-
tive the break begins when transmission of the charac-
ter is completed. If a character is in the TxFIFO, the
start of the break will be delayed until that character, or
any other loaded subsequently are transmitted. The
transmitter must be enabled for this command to be
accepted.
CR[2]—Enable Transmitter
Enables operation of the transmitter. The TxRDY and TxEMT status
bits will be asserted if the transmitter is idle.
0111
Stop break. The TxD line will go High (marking) within
two bit times. TxD will remain High for one bit time be-
fore the next character, if any, is transmitted.
CR[1]—Disable Receiver
This command terminates operation of the receiver immediately—a
character being received will be lost. The command has no effect on
the receiver status bits or any other control registers. If the special
multi-drop mode is programmed, the receiver operates even if it is
disabled. See Operation section.
1000
1001
1010
Assert RTSN. Causes the RTSN output to be asserted
(Low).
Negate RTSN. Causes the RTSN output to be negated
(High)
Set Timeout Mode On. The receiver in this channel will
restart the C/T as the receive character is transferred
from the shift register to the RxFIFO. The C/T is placed
in the counter mode, the START/STOP counter com-
mands are disabled, the counter is stopped, and the
Counter Ready Bit, ISR[3], is reset. (See also Watch-
dog timer description in the receiver section.)
CR[0]—Enable Receiver
Enables operation of the receiver. If not in the special wakeup mode,
this also forces the receiver into the search for start–bit state.
27
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
SR Status Register
Addr
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
SR
RECEIVED
BREAK
FRAMING
ERROR
PARITY
ERROR
OVERRUN
ERROR
TxEMT
TxRDY
FFULL
RxRDY
1
1
1
0x01
0 = No
0 = No
0 = No
0 = No
0 = No
0 = No
0 = No
0 = No
1 = Yes
1 = Yes
1 = Yes
1 = Yes
1 = Yes
1 = Yes
1 = Yes
1 = Yes
1. These status bits are appended to the corresponding data character in the receive FIFO. A read of the status provides these bits [7:5] from
the top of the FIFO together with bits [4:0]. These bits are cleared by a “reset error status” command. In character mode they are discarded
when the corresponding data character is read from the FIFO. In block error mode, the error–reset command (command 4x or receiver
reset) must used to clear block error conditions.
SR[7]— Received Break
This bit indicates that an all zero character of the programmed
length has been received without a stop bit. Only a single FIFO
position is occupied when a break is received: further entries to the
FIFO are inhibited until the RxD line returns to the marking state for
at least one-half a bit time two successive edges of the internal or
external 1X clock. This will usually require a high time of one X1
clock period or 3 X1 edges since the clock of the controller is
not synchronous to the X1 clock.
This bit is cleared by a ‘reset error status’ command.
SR[3]— Transmitter Empty (TxEMT)
This bit will be set when the transmitter under runs, i.e., both the
TxEMT and TxRDY bits are set. This bit and TxRDY are set when
the transmitter is first enabled and at any time it is re-enabled after
either (a) reset, or (b) the transmitter has assumed the disabled
state. It is always set after transmission of the last stop bit of a
character if no character is in the THR awaiting transmission.
When this bit is set, the ‘change in break’ bit in the ISR (ISR[2]) is
set. ISR[2] is also set when the end of the break condition, as
defined above, is detected.
It is reset when the THR is loaded by the CPU, a pending
transmitter disable is executed, the transmitter is reset, or the
transmitter is disabled while in the under run condition.
The break detect circuitry can detect breaks that originate in the
middle of a received character. However, if a break begins in the
middle of a character, it must persist until at least the end of the next
character time in order for it to be detected.
SR[2]— Transmitter Ready (TxRDY)
This bit, when set, indicates that the transmit FIFO is not full and
ready to be loaded with another character. This bit is cleared when
the transmit FIFO is loaded by the CPU and there are (after this
load) no more empty locations in the FIFO. It is set when a
character is transferred to the transmit shift register. TxRDY is reset
when the transmitter is disabled and is set when the transmitter is
first enabled. Characters loaded to the TxFIFO while this bit is 0 will
be lost. This bit has different meaning from ISR[0].
This bit is reset by command 4 (0100) written to the command
register or by receiver reset.
SR[6]— Framing Error
This bit, when set, indicates that a stop bit was not detected (not a
logical 1) when the corresponding data character in the FIFO was
received. The stop bit check is made in the middle of the first stop bit
position.
SR[1]— FIFO Full (FFULL)
This bit is set when a character is transferred from the receive shift
register to the receive FIFO and the transfer causes the FIFO to
become full, i.e., all eight (or 16) FIFO positions are occupied. It is
reset when the CPU reads the receive FIFO. If a character is waiting
in the receive shift register because the FIFO is full, FFULL will not
be reset when the CPU reads the receive FIFO. This bit has
different meaning from IRS when MR1 6 is programmed to a ‘1’.
SR[5]— Parity Error
This bit is set when the ‘with parity’ or ‘force parity’ mode is
programmed and the corresponding character in the FIFO was
received with incorrect parity.
In the special multi-drop mode the parity error bit stores the receive
A/D (Address/Data) bit.
SR[0]— Receiver Ready (RxRDY)
SR[4]— Overrun Error
This bit indicates that a character has been received and is waiting
in the FIFO to be read by the CPU. It is set when the character is
transferred from the receive shift register to the FIFO and reset
when the CPU reads the receive FIFO, only if (after this read) there
are no more characters in the FIFO – the Rx FIFO becomes empty.
This bit, when set, indicates that one or more characters in the
received data stream have been lost. It is set upon receipt of a new
character when the FIFO is full and a character is already in the
receive shift register waiting for an empty FIFO position. When this
occurs, the character in the receive shift register (and its break
detect, parity error and framing error status, if any) is lost.
28
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
OPCR Output Port Configuration Register
Addr
OPCR
0x0D
Bit 7
OP7
BIT 6
OP6
0 = OPR[6]
BIT 5
OP5
0 = OPR[5]
1 = Reserved
BIT 4
OP4
0 = OPR[4]
1 = RxRDY/FFULL
BIT 3
OP3
00 = OPR[3]
01 = C/T OUTPUT
10 = Reserved
11 = Reserved
BIT 2
OP2
BIT 1
OP1
00 = OPR[2]
01 = TxC(16X)
10 = TxC(1X)
11 = RxC(1X)
BIT 0
OP0
0 = OPR[7]
1 = Reserved 1 = TxRDY
OPCR[7]—OP7 Output Select
This bit programs the OP7 output to provide one of the following:
OPCR[3:2]—OP3 Output Select
This bit programs the OP3 output to provide one of the following:
0
1
The complement of OPR[7].
reserved
00 The complement of OPR[3].
01 The counter/timer output, in which case OP3 acts as an
open-drain output. In the timer mode, this output is a square
wave at the programmed frequency. In the counter mode,
the output remains High until terminal count is reached, at
which time it goes Low. The output returns to the High state
when the counter is stopped by a stop counter command.
Note that this output is not masked by the contents of the
IMR.
OPCR[6]—OP6 Output Select
This bit programs the OP6 output to provide one of the following:
0
1
The complement of OPR[6].
The transmitter interrupt output which is the complement of
ISR[0]. When in this mode OP6 acts as an open-drain out-
put. Note that this output is not masked by the contents of
the IMR.
10 Reserved
11 Reserved
OPCR[5]—OP5 Output Select
This bit programs the OP5 output to provide one of the following:
OPCR[1:0]—OP2 Output Select
This field programs the OP2 output to provide one of the following:
0
1
The complement of OPR[5].
Reserved
00 The complement of OPR[2].
01 The 16X clock for the transmitter. This is the clock selected
by CSR[3:0], and will be a 1X clock if CSR[3:0] = 1111.
OPCR[4]—OP4 Output Select
10 The 1X clock for the transmitter, which is the clock that shifts
the transmitted data. If data is not being transmitted, a free
running 1X clock is output.
This field programs the OP4 output to provide one of the following:
0
1
The complement of OPR[4].
The receiver interrupt output which is the complement of
ISR[1]. When in this mode OP4 acts as an open-drain out-
put. Note that this output is not masked by the contents of
the IMR.
11 The 1X clock for the receiver, which is the clock that samples
the received data. If data is not being received, a free run-
ning 1X clock is output.
SOPR—Set the Output Port Bits (OPR)
SOPR[7:0]—Ones in the byte written to this register will cause the corresponding bit positions in the OPR to set to 1. Zeros have no effect. This
allows software to set individual bits with our keeping a copy of the OPR bit configuration.
Addr
SOPR
0x0E
Bit 7
OP 7
1 = set bit
0 = no change
BIT 6
OP 6
1 = set bit
0 = no change
BIT 5
OP 5
1 = set bit
0 = no change
BIT 4
OP 4
1 = set bit
0 = no change
BIT 3
OP 3
1 = set bit
0 = no change
BIT 2
OP 2
1 = set bit
0 = no change
BIT 1
OP 1
1 = set bit
0 = no change
BIT 0
OP 0
1 = set bit
0 = no change
ROPR—Reset Output Port Bits (OPR)
ROPR[7:0]—Ones in the byte written to the ROPR will cause the corresponding bit positions in the OPR to set to 0. Zeros have no effect. This
allows software to reset individual bits with our keeping a copy of the OPR bit configuration.
Addr
ROPR
0x0F
Bit 7
OP 7
1 = reset bit
0 = no change
BIT 6
OP 6
1 = reset bit
0 = no change
BIT 5
OP 5
1 = reset bit
0 = no change
BIT 4
OP 4
1 = reset bit
0 = no change
BIT 3
OP 3
1 = reset bit
0 = no change
BIT 2
OP 2
1 = reset bit
0 = no change
BIT 1
OP 1
1 = reset bit
0 = no change
BIT 0
OP 0
1 = reset bit
0 = no change
29
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
OPR Output Port Register
The output pins (OP pins) drive the compliment of the data in this register as controlled by SOPR and ROPR.
Addr
N/A
Bit 7
OP 7
BIT 6
OP 6
BIT 5
OP 5
BIT 4
OP 4
BIT 3
OP 3
BIT 2
OP 2
BIT 1
OP 1
BIT 0
OP 0
N/A
0 = Pin High 0 = Pin High
1 = Pin Low 1 = Pin Low
0 = Pin High
1 = Pin Low
0 = Pin High
1 = Pin Low
0 = Pin High
1 = Pin Low
0 = Pin High
1 = Pin Low
0 = Pin High
1 = Pin Low
0 = Pin High
1 = Pin Low
ACR Auxiliary Control Register
Addr
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
ACR
BRG SET
Select
Counter Timer Mode
Mode and clock sour select
Delta IP3 int Delta IP3 int Delta IP3 int Delta IP3 int
enable
enable
enable
enable
0x04
0 = set 1
1 = set 2
See table 7
0 = off
1 = enabled
0 = off
1 = enabled
0 = off
1 = enabled
0 = off
1 = enabled
ACR—Auxiliary Control Register
ACR[7]—Baud Rate Generator Set Select
This bit selects one of two sets of baud rates to be generated by the
BRG (see Table 5).
the generation of an interrupt output if IMR [7] = 1. If a bit is in the
‘off’ state, the setting of that bit in the IPCR has no effect on ISR [7].
Table 7. ACR 6:4 field definition
The selected set of rates is available for use by the receiver and
transmitter as described in CSR. Baud rate generator characteristics
are given in Table 6.
ACR
6:4
MODE
CLOCK SOURCE
000
001
010
011
100
101
110
111
Counter
Counter
External (IP2)
TxC – 1X clock of transmitter
reserved
Crystal or X1/CLK clock divided by 16
External (IP2)
External (IP2) divided by 16
Crystal or external clock (X1/CLK)
ACR[6:4]—Counter/Timer Mode And Clock Source Select
This field selects the operating mode of the counter/timer and its
clock source as shown in Table 7
Counter
Timer
Timer
Timer
Timer
ACR [3:0]—IP3, IP2, IP1, IP0 Change-of-State Interrupt Enable
This field selects which bits of the input port change register (IPCR)
cause the input change bit in the interrupt status register (ISR [7]) to
be set. If a bit is in the ‘on’ state the setting of the corresponding bit
in the IPCR will also result in the setting of ISR [7], which results in
Crystal or external clock (X1/CLK) divided
by 16
NOTE:
1. The timer mode generates a square wave
IPCR Input Port change Register
Addr
IPCR
0x04
Bit 7
Delta IP3
BIT 6
Delta IP3
BIT 5
Delta IP3
BIT 4
Delta IP3
BIT 3
IP 3
BIT 2
IP 2
0 = low
1 = High
BIT 1
IP 1
0 = low
1 = High
BIT 0
IP 0
0 = low
1 = High
0 = no change 0 = no change 0 = no change 0 = no change 0 = low
1 = change 1 = change 1 = change 1 = change 1 = High
IPCR [7:4]—IP3, IP2, IP1, IP0 Change-of-State
These bits are set when a change-of-state, as defined in the input
port section of this data sheet, occurs at the respective input pins.
They are cleared when the IPCR is read by the CPU. A read of the
IPCR also clears ISR [7], the input change bit in the interrupt status
register. The setting of these bits can be programmed to generate
an interrupt to the CPU.
IPCR [3:0]—IP3, IP2, IP1, IP0 Change-of-State
These bits provide the current state of the respective inputs. The
information is unlatched and reflects the state of the input pins at the
time the IPCR is read.
30
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
corresponding bit in the IMR is a zero, the state of the bit in the ISR
has no effect on the INTRN output. Note that the IMR does not mask
the reading of the ISR – the true status will be provided regardless
of the contents of the IMR. The contents of this register are
initialized to 0x00’ when the UART is reset.
ISR—Interrupt Status Register
This register provides the status of all potential interrupt sources.
The contents of this register are masked by the Interrupt Mask
Register (IMR). If a bit in the ISR is a ‘1’ and the corresponding bit in
the IMR is also a ‘1’, the INTRN output will be asserted (Low). If the
ISR Interrupt Status Register
Addr
Bit 7
Bits[6:4]
BIT 3
BIT 2
BIT 1
BIT 0
ISR
INPUT
PORT
Ignore in ISR reads.
Reserved for future function
Counter
Ready
Delta
Break
RxRDY/
FFULL
TxRDY
CHANGE
0x05
0 = not active
1 = active
0 = not active 0 = not active 0 = not active 0 = not active
1 = active
1 = active
1 = active
1 = active
ISR[7]—Input Port Change Status
ISR[1]—Rx Interrupt
This bit is a ‘1’ when a change–of–state has occurred at the IP0,
IP1, IP2, or IP3 inputs and that event has been selected to cause an
interrupt by the programming of ACR[3:0]. The bit is cleared when
the CPU reads the IPCR.
This bit indicates that the receiver is interrupting according to the fill
level programmed by the MR0 and MR1 registers. This bit has a
different meaning than the receiver ready/full bit in the status
register.
ISR[6:4]—Not used, Ignore in ISR read.
ISR[0]—Tx Interrupt
This bit indicates that the transmitter is interrupting according to the
interrupt level programmed in the MR0[5:4] bits. This bit has a
different meaning than the TxRDY bit in the status register.
ISR[3]—Counter Ready.
In the counter mode, this bit is set when the counter reaches
terminal count and is reset when the counter is stopped by a stop
counter command.
IMR—Interrupt Mask Register
The programming of this register selects which bits in the ISR
causes an interrupt output. If a bit in the ISR is a ‘1’ and the
corresponding bit in the IMR is also a ‘1’ the INTRN output will be
asserted. If the corresponding bit in the IMR is a zero, the state of
the bit in the ISR has no effect on the INTRN output. Note that the
IMR does not mask the programmable interrupt outputs OP3–OP7
or the reading of the ISR.
In the timer mode, this bit is set once the cycle of the generated
square wave (every other time that the counter/timer reaches zero
count). The bit is reset by a stop counter command. The command,
however, does not stop the counter/timer.
ISR[2]— Change in Break
This bit, when set, indicates that the receiver has detected the
beginning or the end of a received break. It is reset when the CPU
issues a ‘reset break change interrupt’ command.
IMR Interrupt Mask Register
Addr
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
IMR
INPUT
PORT
Reserved
Reserved
Reserved
Counter
Ready
Delta
Break
RxRDY/
FFULL
TxRDY
CHANGE
0x05
0 = not en-
abled
Set to 0
Set to 0
Set to 0
0 = not en-
abled
0 = not en-
abled
0 = not en-
abled
0 = not en-
abled
1 = enabled
1 = enabled
1 = enabled
1 = enabled
1 = enabled
IVR/GP– Interrupt Vector Register (68k mode) or General–purpose register (80XXX mode)
IVR/GP
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
0x0C
Interrupt Vector Register (68XXX mode) or General–purpose register (80XXX mode)
This register stores the Interrupt Vector. It is initialized to 0x0F on
hardware reset and is usually changed from this value during
initialization of the SC28L91 for the 68K Mode. The contents of this
register will be placed on the data bus when IACKN is asserted low
or a read of address 0xC is performed.
When not operating in the 68XXX mode, this register may be used
as a general-purpose one-byte storage register. A convenient use
may the storing a “shadow” of the contents of another SC28L91
register (IMR, for example).
31
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
CTPU and CTPL – Counter/Timer Registers
CTPU Counter Timer Preset Upper
CTPU
0x06
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 2
BIT 1
BIT 1
BIT 0
BIT 0
The lower eight (8) bits for the 16 bit counter timer preset register
CTPL Counter –Timer Preset Low
CTPL
Bit 7
BIT 6
BIT 5
BIT 4
BIT 3
0x07
The Upper eight (8) bits for the 16 bit counter timer preset register
The CTPU and CTPL hold the eight MSbs and eight Labs,
respectively, of the value to be used by the counter/timer in either
the counter or timer modes of operation. The minimum value which
may be loaded into the CTPU/CTPL registers is H‘0002’. Note that
these registers are write-only and cannot be read by the CPU.
counter are read. However, note that a subsequent start counter
command will cause the counter to begin a new count cycle using
the values in CTPU and CTPL.
When the C/T clock divided by 16 is selected, the maximum divisor
becomes 1,048,575.
In the timer mode, the C/T generates a square wave whose period is
twice the value (in C/T clock periods) of the CTPU and CTPL. The
waveform so generated is often used for a data clock. The formula
for calculating the divisor n to load to the CTPU and CTPL for a
particular 1X data clock is shown below.
Output Port Notes
The output ports are controlled from four places: the OPCR register,
the OPR register, the MR registers and the command register
(except the 2681 and 68681) The OPCR register controls the source
of the data for the output ports OP2 through OP7. The data source
for output ports OP0 and OP1 is controlled by the MR and CR
registers. When the OPR is the source of the data for the output
ports, the data at the ports is inverted from that in the OPR register.
n = (C/T Clock Frequency) divided by (2 x 16 x Baud rate desired)
Often this division will result in a non-integer number; 26.3, for
example. One can only program integer numbers in a digital divider.
Therefore 26 would be chosen. This gives a baud rate error of
0.3/26.3 which is 1.14%; well within the ability asynchronous mode
of operation.
The content of the OPR register is controlled by the “Set Output Port
Bits Command” and the “Reset Output Bits Command”. These
commands are at E and F, respectively. When these commands are
used, action takes place only at the bit locations where ones exist.
For example, a one in bit location 5 of the data word used with the
“Set Output Port Bits” command will result in OPR[5] being set to
one. The OP5 would then be set to zero (V SS ). Similarly, a one in
bit position 5 of the data word associated with the “Reset Output
Ports Bits” command would set OPR[5] to zero and, hence, the pin
The C/T will not be running until it receives an initial ‘Start Counter’
command (read at address A3–A0 = 1110). After this, while in timer
mode, the C/T will run continuously. Receipt of a start counter
command (read with A3–A0 = 1110) causes the counter to terminate
the current timing cycle and to begin a new cycle using the values in
CTPU and CTPL. If the value in CTPU and CTPL is changed, the
current half-period will not be affected, but subsequent half periods
will be affected.
OP5 to a one (V ).
DD
The CTS, RTS, CTS Enable Tx signals
The counter ready status bit (ISR[3]) is set once each cycle of the
square wave. The bit is reset by a stop counter command (read with
A3–A0 = 0xF). The command however, does not stop the C/T. The
generated square wave is output on OP3 if it is programmed to be
the C/T output. In the counter mode, the value C/T loaded into
CTPU and CTPL by the CPU is counted down to 0. Counting begins
upon receipt of a start counter command. Upon reaching terminal
count 0x0000, the counter ready interrupt bit (ISR[3]) is set. The
counter continues counting past the terminal count until stopped by
the CPU. If OP3 is programmed to be the output of the C/T, the
output remains high until terminal count is reached, at which time it
goes low. The output returns to the High state and ISR[3] is cleared
when the counter is stopped by a stop counter command. The CPU
may change the values of CTPU and CTPL at any time, but the new
count becomes effective only on the next start counter commands. If
new values have not been loaded, the previous count values are
preserved and used for the next count cycle.
CTS (Clear To Send) is usually meant to be a signal to the
transmitter meaning that it may transmit data to the receiver. The
CTS input is on pin IP0 for Tx. The CTS signal is active low; thus, it
is called CTSN for TxRTS is usually meant to be a signal from the
receiver indicating that the receiver is ready to receive data. It is
also active low and is, thus, called RTSN for Rx. RTSN is on pin
OP0. A receiver’s RTS output will usually be connected to the CTS
input of the associated transmitter. Therefore, one could say that
RTS and CTS are different ends of the same wire!
MR2[4] is the bit that allows the transmitter to be controlled by the
CTS pin (IP0 or IP1). When this bit is set to one AND the CTS input
is driven high, the transmitter will stop sending data at the end of the
present character being serialized. It is usually the RTS output of the
receiver that will be connected to the transmitter’s CTS input. The
receiver will set RTS high when the receiver FIFO is full AND the
start bit of the ninth or 17th character is sensed. Transmission then
stops with nine or 17 valid characters in the receiver. When MR2[4]
is set to one, CTSN must be at zero for the transmitter to operate. If
MR2[4] is set to zero, the IP pin will have no effect on the operation
of the transmitter. MR1[7] is the bit that allows the receiver to control
OP0. When OP0 (or OP1) is controlled by the receiver, the meaning
of that pin will be.
In the counter mode, the current value of the upper and lower 8 bits
of the counter (CTU, CTL) may be read by the CPU. It is
recommended that the counter be stopped when reading to prevent
potential problems which may occur if a carry from the lower 8 bits
to the upper 8 bits occurs between the times that both halves of the
32
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
RESETN
RESETN
t
RES
t
RES
80XXX Mode
68XXX Mode
SD00696
Figure 4. Reset Timing
A0–A3
CEN
t
t
AS
t
AH
t
CS
CH
t
t
RW
RWD
RDN
t
DD
t
DF
NOT
VALID
D0–D7
(READ)
FLOAT
VALID
FLOAT
t
RWD
WDN
t
DS
t
DH
D0–D7
(WRITE)
VALID
SD00087
NOTE:
Bus action in the 80XXX mode terminates on the rise of CEN, WRN, or RDN which ever one occurs first.
Figure 5. Bus Timing (80XXX mode)
33
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
t
CSC
X1/CLK
t
AS
A1–A4
t
CS
t
CH
RWN
t
RWD
t
CSN
AH
t
t
DF
DD
NOT
VALID
D0–D7
DATA VALID
t
DA
DTACKN
t
DAH
t
DCR
t
DAT
NOTE: DACKN low requires two rising edges of X1 clock after CSN is low.
SD00687
Figure 6. Bus Timing (Read Cycle) (68XXX mode)
t
CSC
X1/CLK
t
AS
A1–A4
RWN
t
t
CH
CS
t
RWD
t
CSN
AH
D0–D7
t
DH
t
DS
DTACKN
t
t
DAH
DCW
t
DAT
NOTE: DACKN low requires two rising edges of X1 clock after CSN is low.
SD00688
Figure 7. Bus Timing (Write Cycle) (68XXX mode)
NOTE:
For Figures 6 and 7 WRN changing within the time of CEN low may cause short read or write pulses that could upset internal pointers and
registers. Bus action terminates on the rise of CEN or the fall of DACKN, which ever occurs first.
34
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
t
CSC
X1/CLK
INTRN
IACKN
t
t
DF
DD
D0–D7
t
CSD
t
DAL
DTACKN
t
t
DCR
DAH
t
DAT
NOTE: DACKN low requires two rising edges of X1 clock after CSN is low.
SD00149
Figure 8. Interrupt Cycle Timing (68XXX mode)
RDN
t
t
PH
PS
IP0–IP6
(a) INPUT PINS
WRN
t
PD
OP0–OP7
OLD DATA
NEW DATA
(b) OUTPUT PINS
SD00135
Figure 9. Port Timing
35
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
V
M
WRN
t
IR
1
INTERRUPT
V
+0.5V
OL
OUTPUT
V
OL
V
M
RDN
t
IR
1
INTERRUPT
V
+0.5V
OL
OUTPUT
V
OL
NOTES:
1. INTRN or OP3-OP7 when used as interrupt outputs.
2. The test for open-drain outputs is intended to guarantee switching of the output transistor. Measurement of this response is referenced from the midpoint of the switching
signal, V , to a point 0.5V above V . This point represents noise margin that assures true switching has occurred. Beyond this level, the effects of external circuitry and
M
OL
test environment are pronounced and can greatly affect the resultant measurement.
SD00136
Figure 10. Interrupt Timing (80xxx mode)
t
t
t
t
V
CLK
CTC
Rx
CC
NOTE:
RESISTOR REQUIRED
FOR TTL INPUT.
470Ω
Tx
X1/CLK
CTCLK
RxC
CLK
X1
TxC
t
t
t
t
CLK
CTC
Rx
X2*
*NOTE: X2 MUST BE LEFT OPEN.
SC28L91
Tx
3pF
PARASITIC CAPACITANCE
X1
2pF
C1
50kΩ
to
100kΩ
C2
4pF
X2
TO UART
CIRCUIT
3.6864MHz
3pF
PARASITIC CAPACITANCE
C1 = C2 24pF FOR C = 20pF
L
C1 and C2 should be chosen according to the crystal manufacturer’s specification.
C1 and C2 values will include any parasitic capacitance of the wiring and X1 X2 pins.
Gain at 3.6864MHz: 9 to 13 dB
Package capacitance approximately 4pF.
SD00704
Figure 11. Clock Timing
36
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
1 BIT TIME
(1 OR 16 CLOCKS)
TxC
(INPUT)
t
TXD
TxD
t
TCS
TxC
(1X OUTPUT)
SD00138
Figure 12. Transmitter External Clocks
RxC
(1X INPUT)
t
t
RXH
RXS
RxD
SD00139
Figure 13. Receiver External Clock
TxD
D1
D2
D3
BREAK
D4
D6
TRANSMITTER
ENABLED
TxRDY
(SR2)
WRN
D1
D8
D9
START
BREAK
D10
STOP
BREAK
D11 WILL
NOT BE
D12
WRITTEN TO
THE TxFIFO
1
CTSN
(IP0)
2
RTSN
(OP0)
OPR(0) = 1
OPR(0) = 1
NOTES:
1. Timing shown for MR2(4) = 1.
2. Timing shown for MR2(5) = 1.
SD00155
Figure 14. Transmitter Timing
37
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
D1
D2
D8
D9
D10
D11
D12
D13
RxD
D12, D13 WILL BE LOST
DUE TO RECEIVER DISABLE.
RECEIVER
ENABLED
RxRDY
(SR0)
FFULL
(SR1)
RxRDY/
FFULL
2
(OP5)
RDN
STATUS DATA
STATUS DATA STATUS DATA STATUS DATA
D11 WILL BE LOST
DUE TO OVERRUN
D1
D2
D3
D10
OVERRUN
(SR4)
RESET BY COMMAND
1
RTS
(OP0)
OPR(0) = 1
NOTES:
1. Timing shown for MR1(7) = 1.
2. Shown for OPCR(4) = 1 and MR(6) = 0.
SD00156
Figure 15. Receiver Timing
MASTER STATION
TxD
BIT 9
BIT 9
BIT 9
1
ADD#1
1
D0
0
ADD#2
TRANSMITTER
ENABLED
TxRDY
(SR2)
WRN
MR1(4–3) = 11
MR1(2) = 1
ADD#1 MR1(2) = 0 D0
MR1(2) = 1 ADD#2
PERIPHERAL STATION
BIT 9
BIT 9
1
BIT 9
0
BIT 9
BIT 9
0
0
ADD#1
D0
ADD#2 1
RxD
RECEIVER
ENABLED
RxRDY
(SR0)
RDN/WRN
MR1(4–3) = 11
ADD#1
STATUS DATA
STATUS DATA
ADD#2
D0
SD00096
Figure 16. Wake-Up Mode
38
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
I = 2.4mA
INTRN
DACKN
+5V
125pF
I = 2.4mA V return to V for a 0 level
OL
CC
I = 400µA V
return to V for a 1 level
SS
OH
D0–D7
TxDA/B
OP0–OP7
125pF
SD00690
Figure 17. Test Conditions on Outputs
39
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
PLCC44: plastic leaded chip carrier; 44 leads
SOT187-2
40
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
QFP44: plastic quad flat package; 44 leads (lead length 1.3 mm); body 10 x 10 x 1.75 mm
SOT307-2
41
2000 Sep 22
Philips Semiconductors
Product specification
3.3V–5.0V Universal Asynchronous
Receiver/Transmitter (UART)
SC28L91
Data sheet status
[1]
Data sheet
status
Product
status
Definition
Objective
specification
Development
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
Preliminary
specification
Qualification
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make chages at any time without notice in order to
improve design and supply the best possible product.
Product
specification
Production
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Righttomakechanges—PhilipsSemiconductorsreservestherighttomakechanges, withoutnotice, intheproducts, includingcircuits,standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Copyright Philips Electronics North America Corporation 2000
All rights reserved. Printed in U.S.A.
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Date of release: 09-00
Document order number:
9397 750 07549
Philips
Semiconductors
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SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9135LG-T1-E3
SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9135_11
SMBus Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9136_11
Multi-Output Power-Supply ControllerWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9130CG-T1-E3
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9130LG-T1-E3
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9130_11
Pin-Programmable Dual Controller - Portable PCsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9137
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9137DB
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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SI9137LG
Multi-Output, Sequence Selectable Power-Supply Controller for Mobile ApplicationsWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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VISHAY
SI9122E
500-kHz Half-Bridge DC/DC Controller with Integrated Secondary Synchronous Rectification DriversWarning: Undefined variable $rtag in /www/wwwroot/website_ic37/www.icpdf.com/pdf/pdf/index.php on line 217
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