LTC1318CS [Linear]
IC LINE TRANSCEIVER, PDSO24, PLASTIC, SOL-24, Line Driver or Receiver;
| 型号： | LTC1318CS |
| 厂家： | 
Linear |
| 描述： | IC LINE TRANSCEIVER, PDSO24, PLASTIC, SOL-24, Line Driver or Receiver |
| 文件： | 总8页 (文件大小：215K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1318
Single 5V
RS232/RS422/AppleTalk®
DCE Transceiver
U
DESCRIPTION
FEATURES
The LTC®1318 is a single 5V, RS232/RS422 transceiver
forconnectiontotheDCE,orperipheralsideofaninterface
link. It includes an on-board charge pump to generate a
±8V supply which allows true RS232 output swings. The
charge pump requires only four external 0.1µF capacitors.
The LTC1318 includes two RS232 drivers, a differential
RS422 driver, a dedicated RS232 receiver, and a pin
selectableRS232/RS422receiverwhichcanreceiveeither
single-ended or differential signals.
■
Single Chip Provides DCE RS232 or
RS422/AppleTalkDCE Port
■
Operates from a Single 5V Supply
■
Charge Pump Uses 0.1µF Capacitors
■
Output Common-Mode Voltage Range Exceeds
Power Supply Rails for All Drivers
■
Driver Outputs Are High Impedance with Power Off
Pin Selectable RS232/RS422 Receiver
Thermal Shutdown Protection
■
■
■
Drivers Are Short-Circuit Protected
The LTC1318 features driver outputs which can be taken
to common-mode voltages outside the power supply rails
without damage. Additionally, the driver outputs assume
a high impedance state when the power is shut off,
preventing externally applied signals from feeding back
into the power supplies. The RS232 devices will operate at
speeds up to 100kbaud. The RS422 devices will operate
up to 2Mbaud.
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APPLICATIONS
■
Dual-Mode RS232/RS422 Peripherals
AppleTalkPeripherals
Single 5V Systems
■
■
The LTC1318 is available in a 24-lead SO Wide package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
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TYPICAL APPLICATION
Driver Output Waveforms
+
–
V
V
+
–
+
0.1µF
0.1µF
C1
C1
C2
C2
CHARGE
PUMP
TXD
(5V/DIV)
–
0.1µF
0.1µF
RXI1
TXO1
TXO2
RXO1
TXI1
RS232
RS232
RS232
RS232
LINES
TXD+, TXD–
(2V/DIV)
TXI2
TO
DIGITAL
SYSTEM
V
GND
CC
+
5V
1k
1k
22Ω
22Ω
22Ω
22Ω
22Ω
22Ω
22Ω
22Ω
RS422
RXDO
(5V/DIV)
RXD
RXDO/RXO2
TXD
–
RXD /RXI2
+
RS232
TXD
RXMODE
GND
RL = 100Ω
CL = 100pF
200ns/DIV
1318 TA02
APPLETALK
NETWORK
–
TXD RS422
NC
NC
LTC1318
LT1318 • TA01
LOCALTALK®
TRANSFORMER
100pF × 4
1
LTC1318
W W
W
W
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ABSOLUTE MAXIMUM RATINGS
PACKAGE/ORDER INFORMATION
(Note 1)
Supply Voltage:
ORDER PART
TOP VIEW
VCC ...................................................................................... 7V
V+ ................................................................................... 13.2V
V– ............................................................................... –13.2V
Input Voltage:
NUMBER
+
+
–
–
V
C1
C1
1
2
3
4
5
6
7
8
9
24
V
–
+
23 C2
22 C2
LTC1318CSW
RXI1
TXO1
TXO2
21 RXO1
20 TXI1
All Drivers .............................. – 0.3 to (VCC + 0.3V)
All Receivers ...................................... –25V to 25V
RXMODE Pin ....................... – 0.3V to (VCC + 0.3V)
Output Voltage:
19 TXI2
V
18 GND
CC
+
RXD
17 RXDO/RXO2
16 TXD
RS232 Drivers ................ (V+ – 30V) to (V– + 30V)
RS422 Drivers ................................................ ±15V
All Receivers ........................ – 0.3V to (VCC + 0.3V)
Short-Circuit Duration:
RXD /RXI2
+
–
TXD 10
15 RXMODE
14 GND
–
TXD 11
NC 12
13 NC
V+ or V– to GND .......................................... 30 sec
Driver or Receiver Outputs ...................... Indefinite
Operating Temperature Range .................... 0°C to 70°C
Lead Temperature (Soldering, 10 sec)................. 300°C
SW PACKAGE
24-LEAD PLASTIC SO WIDE
TJMAX = 125°C, θJA = 85°C/W
Consult factory for Industrial and Military grade parts
ELECTRICAL CHARACTERISTICS
VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3)
SYMBOL
Supplies
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Supply Current
No Load
●
9
30
mA
CC
+
V
Positive Charge Pump Output Voltage
I
I
= 0mA
= 10mA, V = 5V
●
●
7.8
6.8
8.8
7.4
V
V
OUT
OUT
CC
–
V
Negative Charge Pump Output Voltage
I
I
= 0mA
●
●
–7.3
–6.3
–8.6
–7.3
V
V
OUT
OUT
= – 5mA, V = 5V
CC
Differential Driver
V
OD
Differential Driver Output Voltage
No Load (Figure 1)
R = 100Ω (Figure 1)
●
●
±4
±2
V
V
L
DV
OD
Change in Magnitude of Differential
Output Voltage
R = 100Ω (Figure 1)
L
●
0.2
V
V
Common-Mode Output Voltage
Short-Circuit Output Current
Input Low Voltage
R = 100Ω (Figure 1)
●
●
●
●
3
V
mA
V
OC
L
I
–1V < V
< 7V
35
200
0.8
DSS
CMR
V
V
IL
Input High Voltage
2.0
V
IH
Single-Ended Driver
V
Output Voltage Swing
Short-Circuit Output Current
Input Low Voltage
R = 3k
●
●
●
●
●
±5
±5
7.3/–6.5
17
V
mA
V
O
L
I
V
= OV
OUT
OSS
V
V
0.8
30
IL
Input High Voltage
2
4
V
IH
SR
Output Slew Rate
R = 3k, C = 51pF
L
20
V/µS
L
2
LTC1318
ELECTRICAL CHARACTERISTICS
VS = 5V ±5%, C1 = C2 = 0.1µF, TA = 0°C to 70°C, unless otherwise specified. (Notes 2, 3)
SYMBOL PARAMETER CONDITIONS
Differential Receiver
MIN
TYP
MAX
UNITS
V
Differential Receiver Threshold
Common-Mode Input Range
Hysteresis
●
●
●
– 0.2
– 7
0.2
7
V
V
TH
CMR
V
= OV
30
5
mV
kΩ
V
CM
R
Input Resistance
TA = 25°C
3
7
IN
V
V
Output Low Voltage
I
I
= –1.6mA
0.4
OL
OUT
OUT
Output High Voltage
Short-Circuit Output Current
= 160µA, V = 5V
●
●
3.5
V
OH
OSS
CC
I
V = GND or V
±7
±85
mA
O
CC
Single-Ended Receiver
V
V
Input Voltage Low Threshold
Input Voltage High Threshold
Hysteresis
●
●
●
0.8
1.4
1.8
0.4
5
V
V
L
2.4
1.0
7
IH
0.1
3
V
R
Input Resistance
TA = 25°C
kΩ
V
IN
V
V
Output Low Voltage
I
I
= –4mA
●
●
●
●
●
●
0.2
4.8
0.4
OL
OUT
OUT
Output High Voltage
= 4mA, V = 5V
3.5
±7
–V
mA
V
OH
OSS
CC
I
Short-Circuit Output Current
RXMODE Input Low Voltage
RXMODE Input High Voltage
RXMODE Input Current
V = GND or V
O
±85
CC
V
V
0.8
1.6
1.6
ILRXM
IHRXM
INRXM
2.0
V
I
V
= OV or V
±2
µA
IN
CC
Switching Characteristics
t
t
t
t
t
Differential Driver Propagation Delay
Differential Driver Output to Output
Differential Driver Rise, Fall Time
Differential Receiver Propagation Delay
Receiver Mode Switching Time
R = 100Ω, C = 100pF (Figures 2,3)
●
●
●
●
●
35
5
100
35
ns
ns
ns
ns
ns
PLH,HL
SKEW
R,F
L
L
R = 100Ω, C = 100pF (Figures 2,3)
L
L
R = 100Ω, C = 100pF (Figures 2,3)
15
110
25
50
L
L
C = 15pF, (Figures 4)
L
200
100
PLH,HL
SEL
Note 2: All currents into device pins are negative, all currents out of device
pins are positive. All voltages are referenced to ground unless otherwise
specified.
The
●
denotes specifications which apply over the full operating
temperature range.
Note 1: Absolute maximum ratings are those values beyond which the life
Note 3: All typicals are given at V = 5V, T = 25°C.
of the device may be impaired.
CC
A
3
LTC1318
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TYPICAL PERFORMANCE CHARACTERISTICS
TTL Input Threshold
vs Temperature
Charge Pump Output Voltage
Supply Current vs Temperature
vs Load Current
10.0
9.8
9.6
9.4
9.2
9.0
8.8
8.6
8.4
8.2
8.0
10
8
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
+
V
CC
= 5V
V
= 5V
V
CC
6
INPUT HIGH (TXI1, TXI2)
INPUT HIGH (TXD)
4
2
T
= 25°C
A
V
= 5V
0
CC
+
–
I
= V TO V
LOAD
–2
–4
–6
–8
–10
INPUT LOW (TXD)
–
INPUT LOW (TXI1, TXI2)
V
10
20
30
40
50
70
0
20
30
40
50
60
70
0
3
6
9
12
15
0
60
60
60
10
TEMPERATURE (°C)
LOAD CURRENT (mA)
TEMPERATURE (°C)
1318 G02
1318 G03
1318 G01
RS422 Driver Single-Ended
Output Swing vs Load Current
RS422 Driver Differential Output
Swing vs Load Current
RS422 Driver Short-Circuit
Current vs Temperature
100
98
96
94
92
90
88
86
84
82
80
10
9
8
7
6
5
4
3
2
1
0
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
T
= 25°C
CC
T
= 25°C
A
V
= 5V
CC
A
V
I
= 5V
V
= 5V
CC
+
I
FROM
FROM TXD ,
LOAD
LOAD
+
–
–
TXD TO TXD
TXD TO GND
+
I
SC
–
I
SC
0
20
30
40
50
70
0
10 20 30 40 50 60 70 80 90 100
0
10 20 30 40 50 60 70 80 90 100
10
TEMPERATURE (°C)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
1318 G04
1318 G05
1318 G06
RS232 Driver Output Swing vs
Resistive Load
RS232 Driver Slew Rate vs
Load Capacitance
RS232 Driver Short-Circuit
Current vs Temperature
10
8
20.0
19.5
19.0
18.5
18.0
17.5
17.0
16.5
16.0
15.5
15.0
25
20
15
10
5
V
= 5V
T
A
= 25°C
CC
V
= 5V
POSITIVE SWING
CC
6
–
SR
4
2
–
+
I
+
SC
SR
T
= 25°C
CC
A
0
V
= 5V
I
SC
–2
–4
–6
–8
–10
NEGATIVE SWING
0
0
20
TEMPERATURE (°C)
30
40
50
70
1
3
6
9 10
2
4
5
7 8
10
10
100
1000
10000
RESISTIVE LOAD (kΩ)
CAPACITANCE (pF)
1318 G07
1318 G08
1318 G09
4
LTC1318
U W
TYPICAL PERFORMANCE CHARACTERISTICS
RS232 Receiver Input Threshold
vs Temperature
TTL Output Short-Circuit Current
vs Temperature
RS422 Receiver Differential
Threshold vs Temperature
100
90
80
70
60
50
40
30
20
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
24
22
20
18
16
14
12
10
V
= 5V
V
= 5V
V
= 5V
CC
CC
CC
RXO1
INPUT HIGH (RXDO/RXO2)
INPUT HIGH (RXO1)
INPUT HIGH
INPUT LOW
RXDO/RXO2
INPUT LOW (RXO1)
INPUT LOW (RXDO/RXO2)
10
20
30
40
50
70
0
60
10
20
30
40
50
70
40
TEMPERATURE (°C)
60
70
0
60
0
10
20
30
50
TEMPERATURE (°C)
TEMPERATURE (°C)
1318 G10
1318 G11
1318 G12
U
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PIN FUNCTIONS
V+ (Pin 1): Charge Pump Positive Output. This pin re-
quires a 0.1µF capacitor to ground. Under normal opera-
tion this pin maintains a voltage of about 8.8V above
ground. An external load can be connected between this
pin and ground or V–.
TXD– (Pin11):DifferentialRS422DriverInvertingOutput.
NC (Pins 12,13): No Internal Connection.
GND (Pins 14, 18): Power Supply Ground. Connect both
pins to each other and to the ground.
C1+, C1– (Pins 2, 3): C1 Inputs. Connect a 0.1µF capacitor
RXMODE (Pin 15): This pin controls the state of the
differential/single-ended receiver. When RXMODE is low,
the receiver is in differential mode and will receive RS422
compatible signals at RXD+ and RXD–/RXI2 (pins 8
and 9). When RXMODE goes high, the receiver enters
single-ended mode and will receive RS232 compatible
signals at RXD–/RXI2. RXD+ is disabled in single-ended
mode. Both modes use the RXDO/RXO2 pin (pin 17) as
their output.
between C1+ and C1–.
RXI1 (Pin 4): First RS232 Single-Ended Receiver Input.
This is an inverting receiver.
TXO1, TXO2 (Pins 5,6): RS232 Single-Ended Driver Out-
puts.
VCC (Pin 7): Positive Supply Input. Apply 4.75V ≤ VCC
≤
5.25V to this pin. A 0.1µF bypass capacitor is required.
TXD (Pin 16): Differential RS422 Driver Input (TTL Com-
RXD+ (Pin 8):When RXMODE (pin 15) is low, this pin acts
as the differential RS422 receiver positive input. When
RXMODE is high, this pin is disabled.
RXD–/RXI2 (Pin 9): When RXMODE (pin 15) is low, this
pin acts as the differential RS422 receiver negative input.
WhenRXMODE ishigh, thispinactsasthesecondRS232
receiver input. The receiver is inverting in RS232 mode.
patible).
RXDO/RXO2(Pin17):Thisistheoutputoftheconfigurable
differential/single-ended receiver.
TXI1, TXI2 (Pins 20, 19): RS232 Driver Inputs (TTL
Compatible). Both are inverting inputs.
RXO1 (Pin 21): First RS232 Receiver Outputs (TTL com-
patible).
TXD+ (Pin 10): Differential RS422 Driver Noninverting
Output.
5
LTC1318
U
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PIN FUNCTIONS
C2+, C2– (Pins 22, 23):C2inputs. Connecta0.1µF capacitor
tion, this pin maintains a voltage of about 8.6V below
ground. An external load can be connected between this
pin and ground or V+.
between C2+ and C2–.
V– (Pin 24): Charge Pump Negative Output. This pin
requiresa0.1µFcapacitortoground.Undernormalopera-
TEST CIRCUITS
+
R /2
L
+
C
C
+
L
L
TXD
RXD
+
TXD
TXD
RXD0/RXD2
TXD
V
R
OD
D
–
–
+
OC
RXD /
TXD
–
TXD
C
RXI2
L
V
R /2
L
–
–
1318 F02
1318 F01
Figure 1.
Figure 2.
U
W
SWITCHING WAVEFORMS
3V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
TXD
1.5V
0V
t
t
PHL
PLH
V
O
+
–
90%
90%
V
= V(TXD ) – V(TXD )
DIFF
50%
10%
50%
10%
–V
O
1/2 V
O
t
t
f
r
–
TXD
V
O
+
TXD
t
t
SKEW
LT1318 • F03
SKEW
Figure 3. Differential Driver
V
OD2
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
+
–
(RXD ) – (RXD )
–V
OD2
t
t
PLH
PHL
V
OH
1.5V
RXDO
1.5V
V
OL
LT1318 • F04
Figure 4. Differential Receiver
6
LTC1318
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APPLICATION INFORMATION
to the C1+/C1– and C2+/C2– pins, and two hold caps, one
from V+ to ground and one from V– to ground. The charge
pump has enough extra capacity to drive light external
loads and still meet RS232 specifications; it will support a
10mA load from V+ to ground or a 5mA from V+ to V–
(Figure 5).
Interface Standards
The LTC1318 provides compatibility with both RS232 and
RS422/AppleTalk/LocalTalk standards in a single chip,
enabling a system to communicate using either protocol
as necessary. The LTC1318 provides two RS232 single-
ended drivers, one RS422 differential driver, and two
receivers. One of the receivers is a dedicated RS232
single-ended receiver, while the other can be configured
for RS232 (single-ended) or RS422 (differential) opera-
tion by controlling the logic state of the select pin. All
single-ended drivers and receivers meet the RS232C
specification for output swing, load driving capacity and
input range, and can additionally transmit and receive
signals as high as 100kbaud. The differential driver and
receiver can interface to both RS422 and AppleTalk net-
works, and can transmit and receive signals at rates
exceeding 2Mbaud.
5V
8V AT 5mA
+
1
2
3
V
0.1µF
0.1µF
0.1µF
EXTERNAL
DEVICE
LTC1318
22
23
0.1µF
–
24
V
–7V AT 5mA
LT1318 • F05
Figure 5.
Fault Protection
Configurable RS422/RS232 Receiver
The LTC1318 incorporates many protection features to
make it as “bustproof” as possible. All driver outputs and
receiver inputs are protected against ESD strikes to ±6kV,
eliminating the need for external protection devices in
most applications. All driver outputs can be taken outside
the power supply rails without damage and will not allow
current to be forced back into the supplies, preventing the
output fault from affecting other logic circuits using the
same power supply. Additionally, the driver outputs enter
a high impedance state when the power is removed,
preventing the system from loading the data lines when it
is shut off. All driver and receiver outputs are protected
against short circuits to ground or to the supply rails.
There are two line receivers in the LTC1318. One is a
dedicated RS232 receiver; the other can receive both
single-ended RS232 signals and differential RS422 sig-
nals. This second receiver has two inputs: RXD+ (pin 8)
and RXD– (pin 9) to accept differential signals. The RXD+
inputisdisabledinsingle-endedmode. Thereceivermode
is set by the RXMODE (pin 15). A low level on RXMODE
configures the receiver in differential mode; it accepts
inputatRXD+ andRXD– andoutputsthedataatRXDO(pin
17). A high level at RXMODE forces the receiver into
single-ended mode; RXD+ is disabled, pin 9 switches
identity from RXD– to RXI2, and pin 17 switches from
RXDOtoRXO2,thesingle-endeddataoutput.Inthismode
the receiver accepts RS232 signals at RXI2 and outputs
the data through RXO2. The receiver becomes inverting in
single-ended mode. This receiver can switch between its
twomodeswithin100ns, allowingthesystemtosensethe
input signal and configure itself accordingly.
Charge Pump Power Supply
The LTC1318 includes an on-board charge pump to gen-
erate the voltages necessary for true RS232 compatible
output swing. This charge pump requires just four exter-
nal 0.1µF capacitors to operate; two flying caps connected
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
7
LTC1318
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
S PACKAGE
24-Lead Plastic SOL
0.598 – 0.614
(15.190 – 15.600)
(NOTE 2)
24 23 22 21 20 19 18
16 15 14 13
17
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
2
3
5
7
8
9
10
1
4
6
11 12
0.291 – 0.299
(7.391 – 7.595)
(NOTE 2)
0.037 – 0.045
(0.940 – 1.143)
0.093 – 0.104
(2.362 – 2.642)
0.005
(0.127)
RAD MIN
0.010 – 0.029
× 45°
(0.254 – 0.737)
0° – 8° TYP
0.050
(1.270)
TYP
0.004 – 0.012
(0.102 – 0.305)
0.009 – 0.013
(0.229 – 0.330)
NOTE 1
0.014 – 0.019
0.016 – 0.050
(0.356 – 0.482)
(0.406 – 1.270)
SOL24 0392
NOTE:
1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS.
2. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006 INCH (0.15mm).
LT/GP 0295 10K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
8
●
●
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LINEAR TECHNOLOGY CORPORATION 1995
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