LTC1323CSW [Linear]
Single 5V AppleTalk Transceiver; 单5V的AppleTalk收发器
| 型号： | LTC1323CSW |
| 厂家： | 
Linear |
| 描述： | Single 5V AppleTalk Transceiver |
| 文件： | 总12页 (文件大小：286K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC1323
Single 5V
AppleTalk® Transceiver
U
DESCRIPTIO
EATURE
S
F
■
Single Chip Provides Complete
TheLTC®1323isamulti-protocollinetransceiverdesigned
to operate on AppleTalk or EIA562-compatible single-
ended networks while operating from a single 5V supply.
TherearetwoversionsoftheLTC1323available:a16-pin
version designed to connect to an AppleTalk network,
and a 24-pin version which also includes the additional
single-ended drivers and receivers necessary to create
an Apple-compatible serial port. An on-board charge
pump generates a –5V supply which can be used to
powerexternaldevices.Additionally,the24-pinLTC1323
features a micropower keep-alive mode during which
oneofthesingle-endedreceiversiskeptactivetomonitor
externalwake-upsignals.TheLTC1323drawsonly2.4mA
quiescent current when active, 65µA in receiver keep-
alive mode, and 0.5µA in shutdown, making it ideal for
useinbattery-poweredsystems.
LocalTalk®/AppleTalk Port
■
■
Operates From a Single 5V Supply
ESD Protection to ±10kV on Receiver Inputs
and Driver Outputs
■
■
■
■
Low Power: ICC = 2.4mA Typ
Shutdown Pin Reduces ICC to 0.5µA Typ
Receiver Keep-Alive Function: ICC = 65µA Typ
Differential Driver Drives Either Differential
AppleTalk or Single-Ended EIA562 Loads
Drivers Maintain High Impedance in Three-State or
with Power Off
■
■
■
Thermal Shutdown Protection
Drivers are Short-Circuit Protected
O U
PPLICATI
A
S
ThedifferentialdrivercandriveeitherdifferentialAppleTalk
loads or conventional single-ended loads. The driver
outputs three-state when disabled, during shutdown, in
receiver keep-alive mode, or when the power is off. The
driver outputs will maintain high impedance even with
output common-mode voltages beyond the power supply
rails. Both the driver outputs and receiver inputs are
protectedagainstESDdamageto±10kV.
■
■
■
LocalTalk Peripherals
Notebook/Palmtop Computers
Battery-Powered Systems
, LTC and LT are registered trademarks of Linear Technology Corporation.
AppleTalk and LocalTalk are registered trademarks of Apple Computer, Inc.
U
O
TYPICAL APPLICATI
LTC1323
5V
1µF
+
24
23
1
CHARGE PUMP
0.33µF
2
5Ω TO 10Ω
5Ω TO 10Ω
=
0.33µF
EMI FILTER
EMI FILTER
CPEN
TXD
3
4
5
6
7
8
9
22
21
1µF
+
100pF
DX
DX
–
TXI
20 TXD
19 TXD
18 TXO
17 RXI
16 RXI
+
TXDEN
SHDN
RXEN
RXO
EMI FILTER
EMI FILTER
EMI FILTER
EMI FILTER
EMI FILTER
EMI FILTER
8
5
7
6
RX
RX
RX
4
3
–
+
RXO 10
RXDO 11
12
15 RXD
14 RXD
13
2
1
LTC1323 • TA01
1
LTC1323
W W W
U
ABSOLUTE AXI U RATI GS
Supply Voltage (VCC) ................................................ 7V
Input Voltage
Logic Inputs .............................. –0.3V to VCC + 0.3V
Receiver Inputs ................................................ ±15V
Driver Output Voltage (Forced) ............................. ±15V
Driver Short-Circuit Duration .......................... Indefinite
Operating Temperature Range .................... 0°C to 70°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
W
U
/O
PACKAGE RDER I FOR ATIO
TOP VIEW
ORDER PART
ORDER PART
NUMBER
+
–
NUMBER
C1
C2
1
2
3
4
5
6
7
8
9
28
V
CC
+
27 C2
26 C2
TOP VIEW
–
LTC1323CG
LTC1323CS
CPEN
TXD
+
C1
C1
1
2
3
4
5
6
7
8
16
V
CC
+
25 NC
24 NC
–
15 C2
TXI
–
TXD
TXDEN
SHDN
RXEN
RXDO
GND
14
13
12
11
10
9
C2
TXDEN
SHDN
RXEN
RXO
23
V
EE
V
EE
–
+
22 TXD
21 TXD
20 TXO
19 RXI
18 RXI
–
+
TXD
TXD
–
RXD
RXD
RXO 10
RXDO 11
NC 12
+
–
+
S PACKAGE
16-LEAD PLASTIC SO
17 RXD
16 RXD
NC 13
TJMAX = 125°C, θJA = 85°C/W
GND 14
15 PGND
G PACKAGE
28-LEAD PLASTIC SSOP
TJMAX = 150°C, θJA = 96°C/W
TOP VIEW
ORDER PART
NUMBER
+
–
C1
C1
1
2
3
4
5
6
7
8
9
24
V
CC
+
23 C2
22 C2
–
LTC1323CSW
CPEN
TXD
21
V
EE
–
+
TXI
20 TXD
19 TXD
18 TXO
17 RXI
16 RXI
TXDEN
SHDN
RXEN
RXO
–
+
RXO 10
RXDO 11
GND 12
15 RXD
14 RXD
13 PGND
SW PACKAGE
24-LEAD PLASTIC SO WIDE
TJMAX = 125°C, θJA = 85°C/W
Consult factory for Industrial and Military grade parts.
2
LTC1323
ELECTRICAL CHARACTERISTICS
VCC = 5V ±10%, TA = 0°C to 70°C (Notes 2, 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Supplies
I
Normal Operation Supply Current
Receiver Keep-Alive Supply Current
Shutdown Supply Current
No Load, SHDN = 0V, CPEN = 0V, TXDEN = 0V,
RXEN = 0V
●
●
●
●
2.4
65
4
mA
µA
µA
V
CC
No Load, SHDN = 0V, CPEN = V , TXDEN = 0V,
100
10
CC
RXEN = 0V
No Load, SHDN = V , CPEN = X, TXDEN = X,
0.5
–5
CC
RXEN = 0V
V
Negative Supply Output Voltage
I
≤ 10mA (Note 4),
LOAD
–5.5
–4.5
EE
V
= 5V, R = 100Ω (Figure 1),
CC
L
TXI = V , R
= 3k (Figure 5)
CC TXO
f
Charge Pump Oscillator Frequency
200
kHz
OSC
Differential Driver
V
Differential Output Voltage
No Load
R = 100Ω (Figure 1)
●
●
±8
±2
V
V
OD
L
∆V
Change in Magnitude of Differential
Output Voltage
R = 100Ω (Figure 1)
L
0.2
3
OD
Differential Driver
V
V
V
Differential Common-Mode
Output Voltage
R = 100Ω
L
V
OC
Single-Ended Output Voltage
No Load
R = 3k to GND
L
●
●
±4.0
±3.7
V
V
OS
Common-Mode Range
Short-Circuit Current
SHDN = V or CPEN = V or Power Off
●
●
●
±10
500
V
mA
µA
CMR
CC
CC
I
I
–5V ≤ V ≤ 5V
35
120
SS
OZ
O
Three-State Output Current
SHDN = V or CPEN = V or Power Off,
±2
±200
CC
CC
–10V ≤ V ≤ 10V
O
Single-Ended Driver (Note 5)
V
OS
Single-Ended Output Voltage
No Load
R = 3k to GND
L
●
●
±4.5
±3.7
V
V
V
Common-Mode Range
SHDN = V or CPEN = V or TXDEN = V
or Power Off
●
±10
V
CMR
CC
CC
CC
CC
I
I
Short-Circuit Current
–5V ≤ V ≤ 5V
●
●
35
220
500
mA
SS
OZ
O
Three-State Output Current
SHDN = V or CPEN = V or TXDEN = V
±2
±200
µA
CC
CC
or Power Off, –10V ≤ V ≤ 10V
O
Receivers
R
Input Resistance
–7V ≤ V ≤ 7V
●
●
●
●
●
●
●
●
●
12
kΩ
mV
mV
V
IN
IN
Differential Receiver Threshold Voltage
Differential Receiver Input Hysteresis
Single-Ended Input, Low Voltage
Single-Ended Input, High Voltage
Output High Voltage
–7V ≤ V ≤ 7V
–200
200
0.8
CM
–7V ≤ V ≤ 7V
70
CM
(Note 5)
(Note 5)
2
V
V
V
I = –4mA
O
3.5
V
OH
Output Low Voltage
I = 4mA
O
0.4
85
V
OL
I
I
Output Short-Circuit Current
Output Three-State Current
–5V ≤ V ≤ 5V
7
mA
µA
SS
OZ
O
–5V ≤ V ≤ 5V, RXEN = V
±2
±100
O
CC
3
LTC1323
ELECTRICAL CHARACTERISTICS VCC = 5V ±10%, TA = 0°C to 70°C (Notes 2 and 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Logic Inputs
V
V
Input High Voltage
Input Low Voltage
Input Current
All Logic Input Pins
All Logic Input Pins
All Logic Input Pins
●
●
●
2.0
V
V
IH
IL
0.8
I
±1.0
±20
µA
C
Switching Characteristics
t
, t
Differential Driver Propagation Delay
R = 100Ω, C = 100pF (Figures 2, 7)
●
●
40
120
180
ns
ns
PLH PHL
L
L
Differential Driver Propagation Delay
with Single-Ended Load
R = 3k, C = 100pF (Figures 3, 9)
120
L
L
Single-Ended Driver Propagation Delay
R = 3k, C = 100pF, (Figures 5, 10) (Note 5)
●
●
●
40
70
70
120
160
160
ns
ns
ns
L
L
Differential Receiver Propagation Delay C = 15pF (Figures 2, 11)
L
Single-Ended Receiver
Propagation Delay
C = 15pF (Figures 6, 12) (Note 5)
L
Inverting Receiver Propagation Delay
in Keep-Alive Mode,
C = 15pF (Figures 6, 12) (Note 5)
L
●
150
600
ns
SHDN = 0V, CPEN = V
CC
t
Differential Driver Output to Output
Differential Driver Rise/Fall Time
R = 100Ω, C = 100pF (Figures 2, 7)
●
●
●
10
50
50
50
ns
ns
ns
SKEW
L
L
t , t
R = 100Ω, C = 100pF (Figures 2, 7)
150
150
r
f
L
L
Differential Driver Rise/Fall Time
with Single-Ended Load
R = 3k, C = 100pF (Figures 3, 9)
L L
Single-Ended Driver Rise/Fall Time
R = 3k, C = 100pF (Figures 5, 10) (Note 5)
●
●
15
80
ns
ns
L
L
t
t
, t
Differential Driver Output Active
to Disable
C = 15pF (Figures 4, 8)
L
180
250
HDIS LDIS
Any Receiver Output Active to Disable
C = 15pF (Figures 4, 13)
●
●
30
100
250
ns
ns
L
, t
Differential Driver
Enable to Output Active
C = 15pF (Figures 4, 8)
L
180
ENH ENL
Any Receiver, Enable to Output Active
C = 15pF (Figures 4, 13)
●
●
30
100
ns
L
V
EER
Supply Rise Time from Shutdown
or Receiver Keep-Alive
C1 = C2 = 0.33µF, C
= 1µF
VEE
0.2
ms
The
●
denotes specifications which apply over the full operating
Note 3: All typicals are given at V = 5V, T = 25°C.
CC A
temperature range.
Note 4: I
is an external current being sunk into the V pin.
EE
LOAD
Note 1: Absolute maximum ratings are those values beyond which the life
of a device may be impaired.
Note 5: These specifications apply to the 24-pin SO Wide package only.
Note 2: All currents into device pins are positive; all currents out of device
pins are negative. All voltages are referenced to ground unless otherwise
specified.
4
LTC1323
W
U
TYPICAL PERFORMANCE CHARACTERISTICS
Single-Ended Driver Swing
vs Load Resistance
Charge Pump Output Voltage
vs Load Current
Differential Driver Swing
vs Load Resistance
5
4
5
4
–2.0
–2.5
–3.0
–3.5
T
= 25°C
= 5V
A
S
V
T
= 25°C
= 5V
A
R
R
V
= 100Ω
L(SE)
= 5V
V
L(DIFF)
= 3k TO GND
TXI
S
3
3
2
2
1
1
0
0
–4.0
–4.5
–1
–2
–3
–4
–5
–1
–2
–3
–4
–5
–5.0
–5.5
–6.0
T
= 25°C
= 5V
A
S
V
5
10
20
50 100 200 300 500 1k 2k 3k 5k 10k
50 100 200 300 500 1k 2k 3k 5k 10k
0
25
30
15
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
LOAD CURRENT (mA)
LTC1323 • TPC01
LTC1323 • TPC02
LTC1323 • TPC03
Differential Driver Swing
vs Temperature
Single-Ended Driver Swing
vs Temperature
Supply Current vs Temperature
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5
4
3.50
V
= 5V
V
= 5V
S
S
V
= 5V
= 3k TO GND
R
= 100Ω
L
S
L
NO LOAD
3.25
3.00
R
3
2
2.75
2.50
2.25
2.00
1.75
1
0
–1
–2
–3
–4
–5
1.50
–25
0
50
75 100 125
–50
25
50
50
TEMPERATURE (°C)
125
–50
0
25
75 100 125
–50
0
25
75 100
–25
–25
TEMPERATURE (°C)
TEMPERATURE (˚C)
LTC1323 • TPC04
LTC1323 • TPC05
LTC1323 • TPC06
5
LTC1323
U
U
U
PI FU CTIO S
LTC1323CS
LTC1323CSW
LTC1323CG
+
+
–
+
–
C1
C1
1
2
3
4
5
6
7
8
16
V
C1
C1
1
2
24
V
C1
C1
1
2
28 V
CC
+
CC
CC
CHARGE PUMP
CHARGE PUMP
CHARGE PUMP
–
+
+
15 C2
14 C2
23 C2
22 C2
27 C2
26 C2
–
–
–
TXD
TXDEN
SHDN
RXEN
RXDO
GND
CPEN
TXD
3
3
CPEN
TXD
DX
DX
DX
DX
13
V
4
21 V
EE
4
25 NC
24 NC
EE
–
–
+
DX
RX
12 TXD
11 TXD
5
20 TXD
19 TXD
18 TXO
17 RXI
16 RXI
TXI
TXI
5
+
–
TXDEN
SHDN
RXEN
RXO
6
TXDEN
SHDN
RXEN
RXO
6
23
22
21
20
V
EE
–
+
10 RXD
7
TXD
TXD
TXO
7
+
9
RXD
8
8
RX
RX
RX
9
9
–
+
RX
10
11
12
15 RXD
14 RXD
10
11
19 RXI
18
RX0
RX0
RXI
RXDO
GND
RXDO
–
+
RX
RX
13 PGND
17 RXD
16 RXD
NC 12
NC
13
GND 14
15
PGND
C1+: C1 Positive Input. Connect a 0.33µF capacitor be-
RXEN: Receiver Enable (TTL compatible). A high level
on this pin disables the receivers and three-states the
logic outputs; a low level allows normal operation.
tween C1+ and C1–.
C1–: C1 Negative Input. Connect a 0.33µF capacitor be-
tween C1+ and C1–.
RXO: Inverting Single-Ended Receiver Output. Remains
active in the receiver keep-alive mode.
CPEN: TTL Level Charge Pump Enable Input. With CPEN
held low, the charge pump is enabled and the chip oper-
ates normally. When CPEN is pulled high, the charge
pump is disabled as well as both drivers, the noninverting
single-ended receiver, and the differential receiver. The
inverting single-ended receiver (RXI) is kept alive to
monitor the control line and ICC drops to 65µA. To turn
off the receiver and drop ICC to 0.5µA, pull the SHDN pin
high.
RXO: Noninverting Single-Ended Receiver Output.
RXDO: Differential Receiver Output.
GND: Signal Ground. Connect to PGND with 24-pin
package.
PGND:Powergroundisconnectedinternallytothecharge
pump and differential driver. Connect to the GND pin.
RXD+: Differential Receiver Noninverting Input. When this
pin is ≥200mV above RXD–, RXDO will be high; when this
pin is ≥200mV below RXD–, RXDO will be low.
RXD–: Differential Receiver Inverting Input.
TXD: Differential Driver Input (TTL compatible).
TXI: Single-Ended Driver Input (TTL compatible).
TXDEN: Differential Driver Output Enable (TTL compat-
ible). A high level on this pin forces the differential driver
into three-state; a low level enables the driver. This input
does not affect the single-ended driver.
RXI: Noninverting Receiver Input. This input controls the
RXO output.
RXI: Inverting Receiver Input. This input controls the RXO
output. In receiver keep-alive mode (CPEN high, SHDN
low), this receiver can be used to monitor a wake-up
control signal.
SHDN: Shutdown Input (TTL compatible). When this pin
is high, the chip is shut down. All driver and receiver
outputsarethree-state,thechargepumpturnsoff,andthe
supply current drops to 0.5µA. A low level on this pin
allows normal operation.
6
LTC1323
U
U
U
PI FU CTIO S
TXO: Single-Ended Driver Output.
C2–: C2 Negative Input. Connect a 0.33µF capacitor
between C2+ and C2–.
TXD+: Differential Driver Noninverting Output.
TXD–: Differential Driver Inverting Output.
C2+: C2 Positive Input. Connect a 0.33µF capacitor
between C2+ and C2–.
VEE: Negative Supply Charge Pump Output. Requires a
1µF bypass capacitor to ground. If an external load is
connected to the VEE pin, the bypass capacitor value
should be increased to 4.7µF.
VCC: Positive Supply Input. 4.5V ≤ VCC ≤ 5.5V. Requires a
1µF bypass capacitor to ground.
TEST CIRCUITS
+
TXD
R
+
C
+
+
L
L
TXD
V
RXD
RXD
OD
RXDO
TXI
TXI
R
L
–
–
R
C
L
–
TXD
RXD
L
V
C
OC
TXD
R
15pF
R
L
C
L
–
LTC1323 • F03
TXD
LTC1323 • F01
LTC1323 • F02
Figure 1
Figure 2
Figure 3
V
CC
S1
TXI
TXO
RXI
RXO
RXI
RXO
500Ω
OUTPUT
R
L
C
L
C
C
L
L
C
L
S2
LTC1323 • F04
LTC1323 • F05
LTC1323 • F06
Figure 4
Figure 5
Figure 6
U
W
SWITCHI G WAVEFOR S
3V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
TXD
1.5V
0V
t
t
PHL
PLH
V
O
+
–
90%
90%
V
DIFF
= V(TXD ) – V(TXD )
50%
10%
50%
10%
–V
O
1/2 V
O
t
t
f
r
–
TXD
V
O
+
TXD
t
t
SKEW
LTC1323 • F07
SKEW
Figure 7. Differential Driver
7
LTC1323
U
W
SWITCHI G WAVEFOR S
3V
1.5V
1.5V
TXDEN
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
0V
t
ZL
t
LZ
5V
+
–
TXD , TXD
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0.5V
V
OL
t
t
HZ
ZH
V
OH
0.5V
–
+
TXD , TXD
2.3V
0V
LTC1323 • F08
Figure 8. Differential Driver Enable and Disable
3V
0V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
1.5V
TXD
–
t
t
PLH
PHL
V
OH
TXD
0V
0V
V
OL
V
+
OH
90%
90%
0V
10%
0V
10%
TXD
V
OL
t
r
t
f
LTC1323 • F09
Figure 9. Differential Driver With Single-Ended Load
3V
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
1.5V
TXI
0V
t
t
PLH
PHL
V
OH
90%
90%
LTC1323 • F10
TXO
0V
10%
0V
10%
V
OL
t
r
t
r
Figure 10. Single-Ended Driver
V
OD2
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
+
–
0V
0V
(RXD ) – (RXD )
–V
OD2
t
t
PLH
PHL
V
OH
1.5V
RXDO
1.5V
V
OL
LTC1323 • F11
Figure 11. Differential Receiver
8
LTC1323
U
W
SWITCHI G WAVEFOR S
V
IH
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
1.5V
1.5V
RXI, RXI
V
IL
t
t
PLH
PHL
V
OH
2.4V
1.5V
RXI
0.8V
1.5V
V
OL
V
IH
V
RXI
LTC1323 • F12
Figure 12. Single-Ended Receiver
3V
1.5V
1.5V
RXEN
f = 1MHz: t ≤ 10ns: t ≤ 10ns
r
f
0V
5V
t
t
LZ
ZL
RXO, RXO, RXDO
2.3V
2.3V
OUTPUT NORMALLY LOW
OUTPUT NORMALLY HIGH
0.5V
V
OL
t
ZH
t
HZ
V
OH
0.5V
RXO, RXO, RXDO
0V
LTC1323 • F13
Figure 13. Receiver Enable and Disable
U U
W
U
APPLICATIO S I FOR ATIO
Functional Description
to improve lifetime in battery-powered devices. The 24-
pin SO Wide version also includes a receiver keep-alive
mode for monitoring external signals while drawing 65µA
typically.
The “serial port” on the back of an Apple-compatible
computer or peripheral is a fairly versatile “multi-protocol”
connector. It must be able to connect to a wide bandwidth
LAN (an AppleTalk/LocalTalk network), which requires a The LTC1323 includes an RS422-compatible differential
high speed differential transceiver to meet the AppleTalk driver/receiver pair for data transmission, with the driver
specification, and it must also be able to connect directly to specified to drive 2V into the 100Ω primary of a typical
a printer or modem through a short RS232 style link. The LocalTalk interface transformer/RFI interference network.
LTC1323isdesignedtoprovideallthefunctionsnecessary EitheroutputofthedifferentialRS422drivercanalsoactas
to implement such a port on a single chip. Two versions of an single-ended driver, allowing the LTC1323 to commu-
the LTC1323 are available: a 16-pin SO version which nicate over a standard serial connection. The 24-pin SO
provides the minimum solution for interfacing to an Wide LTC1323 also includes an extra single ended only
AppleTalknetworkinasmallerpackage,andalarger24-pin driver and two extra RS232-compatible single-ended re-
SO Wide version which additionally includes all the hand- ceivers for handshaking lines. All versions include an on-
shaking lines required to implement a complete AppleTalk/ board charge pump to provide a regulated –5V supply
modem/printer serial port. All LTC1323s run from a single required for the single-ended drivers. The charge pump
5V power supply while providing true single-ended com- can also provide up to 10mA of external load current to
patibility, and include a 0.5µA low power shutdown mode
power other circuitry.
9
LTC1323
U U
W
U
APPLICATIO S I FOR ATIO
Driving Differential AppleTalk or Single-Ended Loads
Power Shutdown
ThepowershutdownfeatureoftheLTC1323isdesigned
for battery-powered systems. When SHDN is forced
high the part enters shutdown mode. In shutdown the
supply current typically drops from 2.4mA to 0.5µA , the
charge pump turns off, and the driver and receiver
outputs are three-stated.
The differential driver is able to drive either an AppleTalk
load or a single-ended load such as a printer or modem.
With a differential AppleTalk load, TXD+ and TXD– will
typically swing between 1.2V and 3.5V (Figure 14a). With
a single-ended 3k load such as a printer, either TXD+ or
TXD– will meet the single-ended voltage swing require-
mentof±3.7V(Figure14b). Anautomaticswitchingcircuit
preventsthedifferentialdriverfromoverloadingthecharge
pump if the outputs are shorted to ground while driving
single-ended signals. This allows the second single-ended
driver to continue to operate normally when the first is
shorted,andallowsexternalcircuitryattachedtothecharge
pump output to continue to operate even if there are faults
at the driver outputs.
Receiver Keep-Alive Mode (24-Pin SO Wide Only)
The 24-pin SO Wide version of the LTC1323 also features
a power saving receiver keep-alive mode. When CPEN is
pulled high the charge pump is turned off and the outputs
of both drivers, the noninverting single-ended receiver and
the differential receiver are forced into three-state. The
inverting single-ended receiver (RXI) is kept alive with ICC
dropping to 65µA and the receiver delay time increasing to
a maximum of 400ns. The receiver can then be used to
monitor a wake-up control signal.
V
= 5V
CC
+
24
1µF
C1
V
CC
12
13
EXTERNAL
CHIP
GND
LTC1323
21
Charge Pump Capacitors and Supply Bypassing
V
EE
The LTC1323 requires two external 0.33µF capacitors for
the charge pump to operate: one from C1+ to C1– and one
from C2+ to C2–. These capacitors should be low ESR
types and should be mounted as close as possible to the
LTC1323. Monolithic ceramic capacitors work well in this
application. Do not use capacitors greater than 2µF at the
charge pump pins or internal peak currents can rise to
destructivelevels.TheLTC1323alsorequiresthatbothVCC
and VEE be well bypassed to ensure proper charge pump
operation and prevent data errors. A 1µF capacitor from
VCC togroundisadequate. A1µFcapacitorisrequiredfrom
VEE to ground and should be increased to 4.7µF if an
external load is connected to the VEE pin. Ceramic or
tantalum capacitors are adequate for power supply by-
passing; aluminum electrolytic capacitors should only be
used if their ESR is low enough for proper charge pump
operation. Inadequate bypass or charge pump capacitors
will cause the charge pump output to go out of regulation
prematurely, degrading the output swing at the SINGLE-
ENDED driver outputs.
I
VEE
4.7µF
–5.5V ≤ V ≤ –4.5V
EE
+
I
≤ 10mA
VEE
LTC1323 • F15
Figure 14
Thermal Shutdown Protection
The LTC1323 includes a thermal shutdown circuit which
protects against prolonged shorts at the driver outputs. If
adriveroutputisshortedtoanotheroutputortothepower
supply, the current will be initially limited to a maximum of
500mA. When the die temperature rises above 150°C, the
thermal shutdown circuit disables the driver outputs.
When the die cools to about 130°C, the outputs are re-
enabled. If the short still exists, the part will heat again and
the cycle will repeat. This oscillation occurs at about 10Hz
and prevents the part from being damaged by excessive
powerdissipation.Whentheshortisremoved,thepartwill
return to normal operation.
10
LTC1323
U U
W
U
APPLICATIO S I FOR ATIO
Driving an External Load from VEE
the LTC1323 uses a single supply differential driver, the
resistor values should be reduced to 5Ω to 10Ω to guaran-
tee adequate voltage swing on the cable (Figure 16a). In
mostapplications, removingtheresistorscompletelydoes
not cause an increase in EMI as long as a shielded connec-
tor and cable are used (Figure 16b). With the resistors
removed the only DC load is the primary resistance of the
LocalTalk transformer. This will increase the DC standby
current when the driver outputs are active, but does not
adversely affect the drivers because they can handle a
direct indefinite short circuits without damage. Trans-
formerprimaryresistanceshouldbeabove15Ωtokeepthe
LTC1323 operating normally and prevent it from entering
thermal shutdown. For maximum swing and EMI immu-
nity, a ferrite bead and capacitor T network can be used
(Figure 16c).
An external load may be connected between ground and
the VEE pin as shown in Figure 15. The LTC1323 VEE pin
will sink up to a maximum of 10mA while maintaining the
pin voltage between –4.5V and –5.5V. If an external load
is connected, the VEE bypass capacitor should be in-
creased to 4.7µF. Both LTC1323 and the external chip
should have separate VCC bypass capacitors but can
share the VEE capacitor.
EMI Filter
Most LocalTalk applications use an electromagnetic inter-
ference (EMI) filter consisting of a resistor-capacitor T
network between each driver and receiver and the connec-
tor. Unfortunately, the resistors significantly attenuate the
driversoutputsignalsbeforetheyreachthecable. Because
FERRITE BEAD FERRITE BEAD
5Ω TO 10Ω
5Ω TO 10Ω
V
= 5V
CC
100pF
100pF
100pF
+
24
1µF
C1
V
CC
12
13
(a)
(b)
(c)
LTC1323 • F16
EXTERNAL
CHIP
GND
LTC1323
21
Figure 16. EMI Filters
V
EE
I
VEE
4.7µF
–5.5V ≤ V ≤ –4.5V
EE
+
I
≤ 10mA
VEE
LTC1323 • F15
Figure 15
U
TYPICAL APPLICATIONS N
Typical LocalTalk Connection
5V
+
1µF
16
1
2
15
0.33µF
0.33µF
CHARGE PUMP
14
13
1µF
+
LTC1323CS
TX
100pF
LocalTalk
TRANSFORMER
12
11
3
DATA IN
4
5
6
TX ENABLE
120Ω
100pF
100pF
SHDN
RX ENABLE
10
9
7
DATA OUT
RX
8
LTC1323 • TA02
100pF
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.
11
LTC1323
U
Dimensions in inches (millimeters) unless otherwise noted.
PACKAGE DESCRIPTION
G Package
28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
0.397 – 0.407*
(10.07 – 10.33)
0.205 – 0.212**
(5.20 – 5.38)
0.068 – 0.078
(1.73 – 1.99)
28 27 26 25 24 23 22 21 20 19 18
16 15
17
0° – 8°
0.301 – 0.311
(7.65 – 7.90)
0.0256
(0.65)
BSC
0.005 – 0.009
0.022 – 0.037
(0.55 – 0.95)
(0.13 – 0.22)
0.002 – 0.008
(0.05 – 0.21)
0.010 – 0.015
(0.25 – 0.38)
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
5
7
1
2
3
4
6
8
9
10 11 12 13 14
G28 SSOP 0694
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
0.010 – 0.020
16
15
14
13
12
11
10
9
× 45°
0.004 – 0.010
(0.101 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0° – 8° TYP
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.050
(1.270)
TYP
0.014 – 0.019
(0.355 – 0.483)
0.016 – 0.050
0.406 – 1.270
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
S16 0695
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
1
2
3
4
5
6
7
8
SW Package
24-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.598 – 0.614*
(15.190 – 15.600)
0.291 – 0.299**
(7.391 – 7.595)
0.037 – 0.045
(0.940 – 1.143)
0.093 – 0.104
(2.362 – 2.642)
24 23 22 21 20 19 18
16 15 14 13
17
0.010 – 0.029
(0.254 – 0.737)
× 45°
0° – 8° TYP
0.050
(1.270)
TYP
0.394 – 0.419
(10.007 – 10.643)
NOTE 1
0.009 – 0.013
0.004 – 0.012
(0.102 – 0.305)
NOTE 1
(0.229 – 0.330)
0.014 – 0.019
(0.356 – 0.482)
0.016 – 0.050
(0.406 – 1.270)
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.
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
2
3
5
7
8
9
10
1
4
6
11 12
S24 (WIDE) 0695
LT/GP 1194 10K • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
12
●
●
LINEAR TECHNOLOGY CORPORATION 1994
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
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