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LT1342 5V RS232 Transceiver with 3V Logic Interface
FEATURES
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DESCRIPTIO
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ESD Protection Over 10kV 3V Logic Interface Uses Small Capacitors: 0.1F, 0.2F 1A Supply Current in Shutdown Low Power Driver Disable Operating Mode Pin Compatible with LT1137A 120kBaud Operation for RL = 3k, CL = 2500pF 250kBaud Operation for RL = 3k, CL = 1000pF CMOS Comparable Low Power: 60mW Operates from a 5V Supply and 3V Logic Supply Easy PC Layout: Flowthrough Architecture Rugged Bipolar Design Outputs Assume a High Impedance State When Off or Powered Down Absolutely No Latchup
The LT(R)1342 is an advanced low power three-driver, fivereceiver RS232 transceiver. The LT1342 operates from a 5V supply and a 3V logic supply. Receiver outputs can interface directly to 3V logic circuits. Included on the chip is a shutdown pin for reducing supply current to near zero. All receivers and drivers assume high impedance states during shutdown. The driver disable function provides additional control of operating mode. When driver disable is high the charge pump and drivers turn off. Receivers continue to operate during driver disable. New ESD structures on the chip allow the LT1342 to survive multiple 10kV strikes, eliminating the need for costly TransZorbs(R) on the RS232 line pins. The LT1342 is fully compliant with all EIA RS232 specifications and operates in excess of 120kbaud even driving heavy capacitive loads.
, LTC and LT are registered trademarks of Linear Technology Corporation. TransZorb is a registered trademark of General Instruments, GSI.
APPLICATI
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Notebook Computers Palmtop Computers
TYPICAL APPLICATI
V+ 0.1F 2 x 0.1F DRIVER 1 OUT RX1 IN DRIVER 2 OUT TO LINE RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN ON/OFF 3V VL 5V VCC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 LT1342
28 V - 27 26 25 24 23 22 21 20 19 18 17 16 15 DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC
LT1342 * TA01
0.1F 2 x 0.1F
RECEIVER OUTPUT VL = 3V CL = 50pF DRIVER ROUTPUT RL = 3k CL = 2500pF
TO 3V LOGIC
INPUT
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Output Waveforms
LT1342 * TA02
UO
UO
1
LT1342 ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW V+ C1+ C1- 1 3 4 28 V-
Supply Voltage (VCC) ................................................ 6V Supply Voltage (VL) .................................................. 6V V + ........................................................................ 13.2V V - ...................................................................... -13.2V Input Voltage Driver ........................................................... V - to V + Receiver ................................................ - 30V to 30V Output Voltage Driver .................................................... - 30V to 30V Receiver .................................... - 0.3V to VCC + 0.3V Short-Circuit Duration V + ................................................................... 30 sec V - ................................................................... 30 sec Driver Output .............................................. Indefinite Receiver Output .......................................... Indefinite Operating Temperature Range .................... 0C to 70C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
ORDER PART NUMBER LT1342CG LT1342CNW LT1342CSW
5V VCC 2
27 C2 - 26 C2+ 25 DRIVER 1 IN 24 RX1 OUT 23 DRIVER 2 IN 22 RX2 OUT 21 RX3 OUT 20 RX4 OUT 19 DRIVER 3 IN 18 RX5 OUT 17 GND 16 DRIVER DISABLE 15 NC
DRIVER 1 OUT 5 RX1 IN 6 DRIVER 2 OUT 7 RX2 IN 8 RX3 IN 9 RX4 IN 10 DRIVER 3 OUT 11 RX5 IN 12 ON/OFF 13 3V VL 14
G PACKAGE NW PACKAGE 28-LEAD PLASTIC SSOP 28-LEAD WIDE PDIP SW PACKAGE 28-LEAD WIDE PLASTIC SO
TJMAX = 125C, JA = 96C/ W (G) TJMAX = 125C, JA = 56C/ W (NW) TJMAX = 125C, JA = 85C/ W (SW)
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER Power Supply Generator V + Output V - Output Supply Current (VCC) Logic Supply Current (VL) Supply Current When OFF (VCC) Logic Supply Current (VL) When OFF Supply Rise Time Shutdown to Turn-On ON/OFF Pin Thresholds ON/OFF Pin Current DRIVER DISABLE Pin Thresholds DRIVER DISABLE Pin Current Oscillator Frequency CONDITIONS
(Note 2)
MIN TYP 8.6 -7 12 0.1 1 3 1 0.1 0.2 1.4 1.4 1.4 1.4 130 MAX UNITS V V mA mA A mA A mA ms V V A V V A kHz
(Note 3) (Note 4) Shutdown (Note 5) Driver Disable Shutdown (Note 5) Driver Disable C1 = C2 = 0.2F, C + = C - = 0.1F Input Low Level (Device Shutdown) Input High Level (Device Enabled) 0V VON/OFF 5V Input Low Level (Drivers Enabled) Input High Level (Drivers Disabled) 0V VDRIVER DISABLE 5V
q q
17 1 10 10 1
q q q q q q
0.8 80 0.8 500
2.4 -15 2.4 -10
2
U
W
U
U
WW
W
LT1342
ELECTRICAL CHARACTERISTICS
PARAMETER Any Driver Output Voltage Swing Logic Input Voltage Level Logic Input Current Output Short-Circuit Current Output Leakage Current Data Rate (Note 8) Slew Rate Propagation Delay Any Receiver Input Voltage Thresholds Hysteresis Input Resistance Output Leakage Current Receivers 1 Through 4 Output Voltage Output Short-Circuit Current Propagation Delay Receiver 5 Output Voltage Output Short-Circuit Current Propagation Delay CONDITIONS Load = 3k to GND
(Note 2)
MIN Positive Negative
q q q q q
TYP 7.3 - 6.5 1.4 1.4 5 17 10
MAX
UNITS V V V V A mA A kBaud kBaud V/s V/s s s V V V k A V V mA mA ns ns V V mA mA s s
5
Input Low Level (VOUT = High) Input High Level (VOUT = Low) 0.8V VIN 2V VOUT = 0V Shutdown, VOUT = 30V (Note 5) RL = 3k, CL = 2500pF RL = 3k, CL = 1000pF RL = 3k, CL = 51pF RL = 3k, CL = 2500pF Output Transition tHL High to Low (Note 6) Output Transition tLH Low to High Input Low Threshold (VOUT = High) Input High Threshold (VOUT = Low)
-5 0.8 20 100
2 9
q
120 250 4 15 6 0.6 0.5 1.3 1.7 0.4 5 1 0.2 2.9 - 20 20 250 350 0.2 2.9 -4 4 1 1 30 1.3 1.3
0.8
q
0.1 3
Shutdown (Note 4) 0 VOUT VCC Output Low, IOUT = - 1.6mA Output High, IOUT = 160A Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition tLH Low to High Output Low, IOUT = - 500A Output High, IOUT = 160A Sinking Current, VOUT = VCC Sourcing Current, VOUT = 0V Output Transition tHL High to Low (Note 7) Output Transition tLH Low to High
q q q
2.4 1 7 10 0.4 -10 600 600 0.4 -2 3 3
2.7 10
q q
2.7 2
The q denotes specifications which apply over the full operating temperature range (0C TA 70C for commercial grade). Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Testing done at VCC = 5V, VL = 3.3V and VON/OFF = 3V. Note 3: Supply current is measured with external capacitors C + = C - = 0.1F, C1 = C2 = 0.2F. All outputs are open with all driver inputs tied high. Note 4: VL supply current is measured with all receiver outputs high. Note 5: Supply current and leakage measurements in shutdown are performed with VON/OFF 0.1V. Supply current measurements using driver disable are performed with VDRIVER DISABLE 3V.
Note 6: For driver delay measurements, RL = 3k and CL = 51pF. Trigger points are set between the driver's input logic threshold and the output transition to the zero crossing (t HL = 1.4V to 0V and tLH = 1.4V to 0V). Note 7: For receiver delay measurements, CL = 51pF. Trigger points are set between the receiver's input logic threshold and the output transition to standard TTL/CMOS logic threshold (t HL = 1.3V to 2.4V and tLH = 1.7V to 0.8V). Note 8: Data rate operation guaranteed by slew rate, short-circuit current and propagation delay tests.
3
LT1342
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Output Voltage
10 8
DRIVER OUTPUT VOLTAGE (V)
RL = 3k
OUTPUT HIGH
THRESHOLD VOLTAGE (V)
6 4 2 0 -2 -4 -6 -8 -10 -55 -25
2.25 2.00 1.75 1.50 1.25 1.00 0.75 INPUT LOW INPUT HIGH
SUPPLY CURRENT (mA)
VCC = 5.5V VCC = 5V VCC = 4.5V
VCC = 4.5V VCC = 5V VCC = 5.5V
OUTPUT LOW 50 25 0 75 TEMPERATURE (C) 100 125
Supply Current in Shutdown
150 125 100 75 50 25 0 -55 -25
SUPPLY CURRENT (mA)
THRESHOLD VOLTAGE (V)
SUPPLY CURRENT (A)
50 25 75 0 TEMPERATURE (C)
ON/OFF Thresholds
3.0 2.5
THRESHOLD VOLTAGE (V)
40 35
SUPPLY CURRENT (mA)
30 25 20 15 10 5
LEAKAGE CURRENT ( A)
2.0 1.5 1.0
ON THRESHOLD
OFF THRESHOLD 0.5 0 -55 -25
50 25 75 0 TEMPERATURE (C)
4
UW
LT1342 * TPC01
Receiver Input Thresholds
3.00 2.75 2.50
Supply Current vs Data Rate
80 70 60 50 40 30 20 10 3DRIVERS ACTIVE RL = 3k CL = 2500pF
0.50 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
0 0 25 75 50 100 DATA RATE (kBAUD) 125 150
LT1342 * TPC02
LT1342 * TPC03
Supply Current in Driver Disable
5
3.0 2.5 2.0 1.5 1.0 0.5
Driver Disable Threshold
4
3
2
1
100
125
0 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
0 -55 -25
50 25 75 0 TEMPERATURE (C)
100
125
LT1342 * TPC04
LT1342 * TPC05
LT1342 * TPC06
Supply Current
100
Driver Leakage in Shutdown
3DRIVERS LOADED R L = 3k 2DRIVERS LOADED R L = 3k 1DRIVER LOADED R L = 3k NO LOAD
10
1
VOUT = 30V VOUT = -30V
100
125
0 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
0.1 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
LT1342 * TPC07
LT1341 * TPC08
LT1342 * TPC09
LT1342
TYPICAL PERFOR A CE CHARACTERISTICS
Driver Short-Circuit Current
30
SHORT-CIRCUIT CURRENT (mA)
25 20 15
SHORT-CIRCUIT CURRENT (mA)
10 5 0 -55 -25
50 25 75 0 TEMPERATURE (C)
Receiver Output Waveforms
RX5 OUTPUT CL = 50pF DRIVER OUTPUT RL = 3k
RX1 TO RX4 OUTPUT CL = 50pF
INPUT VL = 3V
LT1342 * TPC12
PI FU CTIO S
VCC: 5V Input Supply Pin. This pin should be decoupled with a 0.1F ceramic capacitor close to the package pin. Insufficient supply bypassing can result in low output drive levels and erratic charge pump operation. VL: 3V Logic Supply Pin. Provides power to the receiver outputs. Decouple with a 0.1F ceramic capacitor. GND: Ground Pin. ON/OFF: A TTL/CMOS Compatible Operating Mode Control. A logic low puts the device in the low power shutdown mode. Drivers and receivers assume a high impedance state in shutdown. The transceiver consumes almost no supply current while in shutdown. A logic high fully enables the transceiver. An ON/OFF logic low signal supersedes the state of the DRIVER DISABLE pin. DRIVER DISABLE: This pin provides an alternate control for the charge pump and RS232 drivers. A logic high on this pin shuts down the charge pump and places all drivers in a high impedance state. All five receivers remain active under these conditions. Floating the DRIVER DISABLE pin or driving it to a logic low level fully enables the transceiver. A logic low on the ON/OFF pin supersedes the state of the DRIVER DISABLE pin. Supply current drops to 3mA when in driver disable mode. V +: Positive Supply Output (RS232 Drivers). V + 2VCC - 1.5V. This pin requires an external charge storage capacitor C 0.1F, tied to ground or VCC. With multiple transceivers, the V + and V - pins may be paralleled into common charge storage capacitors. Larger value capacitors may be used to reduce supply ripple.
UW
Receiver Short-Circuit Current
50
ISC+
40
RX1 TO RX4 ISC- RX1 TO RX4 ISC+ RX5 ISC-
30
ISC-
20
10
RX5 ISC+
100
125
0 -55 -25
50 25 0 75 TEMPERATURE (C)
100
125
LT1342 * TPC10
LT1342 * TPC11
Driver Output Waveforms
DRIVER OUTPUT RL = 3k CL = 2500pF
INPUT
LT1342 * TPC13
U
U
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5
LT1342
PI FU CTIO S
V -: Negative Supply Output (RS232 Drivers). V - -(2VCC - 2.5V). This pin requires an external charge storage capacitor C 0.1F. To reduce supply ripple, increase the size of the storage capacitor. C1+, C1-, C2+, C2 -: Commutating Capacitor Inputs. These pins require two external capacitors C 0.2F: one from C1+ to C1-, and another from C2 + to C2 -. The capacitor's effective series resistance should be less than 2. For C 1F, low ESR tantalum capacitors work well in this application, although small value ceramic capacitors may be used with a minimal reduction in charge pump compliance. For operation with an external 12V supply, omit C1 and connect the 12V supply to pin C1+. Pin V + may also be shorted to C1+ when a separate supply is used. The 12V supply must be bypassed with a 0.1F capacitor. DRIVER IN: RS232 Driver Input Pins. These inputs are compatible with TTL or CMOS logic. Tie unused inputs to VCC or VL. DRIVER OUT: Driver Outputs at RS232 Voltage Levels. Driver output swing meets RS232 levels for loads up to 3k. Slew rates are controlled for lightly loaded lines. Output current capability is sufficient for load conditions up to 2500pF. Outputs are in a high impedance state when in shutdown mode, VCC = 0V, or when the DRIVER DISABLE pin is active. Outputs are fully shortcircuit protected from V - + 30V to V + - 30V. Applying higher voltages will not damage the device if the overdrive is moderately current limited. Short circuits on one output can load the power supply generator and may disrupt the signal levels of the other outputs. The driver outputs are protected against ESD to 10V for human body model discharges. RX IN: Receiver Inputs. These pins accept RS232 level signals (30V) into a protected 5k terminating resistor. The receiver inputs are protected against ESD to 10kV for human body model discharges. Each receiver provides 0.4V of hysteresis for noise immunity. Open receiver inputs assume a logic low state. RX OUT: Receiver Outputs with 3.3V Logic Compatible Voltage Levels. Outputs are in a high impedance state when in shutdown mode to allow data line sharing. Outputs are fully short-circuit protected to ground or VCC or VL with the power on, off, or in shutdown mode. Receiver output level is determined by VL supply voltage. Use VL = 3.3V for interfacing with 3.3V logic, VL = 5V for interfacing with 5V logic.
ESD PROTECTIO
The RS232 line inputs of the LT1342 have on-chip protection from ESD transients up to 10kV. The protection structures act to divert the static discharge safely to system ground. In order for the ESD protection to function effectively, the power supply and ground pins of the LT1342 must be connected to ground through low impedances. The power supply decoupling capacitors and charge pump storage capacitors provide this low impedance in normal application of the circuit. The only constraint is that low ESR capacitors must be used for bypassing and charge storage. ESD testing must be done with pins VCC, V +, V - and GND shorted to ground or connected with low ESR capacitors.
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ESD Test Circuit
V+ 5V VCC 0.1F 0.1F 0.2F DRIVER 1 OUT RX1 IN DRIVER 2 OUT RS232 LINE PINS PROTECTED TO 10kV RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN 1 2 3 4 5 6 7 8 9 10 11 12 LT1342 28 27 26 25 24 23 22 21 20 19 18 17 16 15 V- 0.1F 0.2F DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC
LT1342 * ESD TC
13 ON/OFF 14 3V VL 0.1F
LT1342
PACKAGE DESCRIPTIO
0.205 - 0.212** (5.20 - 5.38) 0 - 8
0.005 - 0.009 0.022 - 0.037 (0.13 - 0.22) (0.55 - 0.95)
*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
0.600 - 0.625 (15.240 - 15.875)
0.150 0.005 (3.810 0.127) 0.015 (0.381) MIN
0.045 - 0.065 (1.143 - 1.651)
0.009 - 0.015 (0.229 - 0.381)
(
+0.035 0.625 -0.015 +0.889 -0.381
15.87
)
0.125 (3.175) MIN
0.035 - 0.080 (0.889 - 2.032) 0.100 0.010 (2.540 0.254)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
0.291 - 0.299** (7.391 - 7.595) 0.010 - 0.029 x 45 0.093 - 0.104 (2.362 - 2.642) (0.254 - 0.737) 0 - 8 TYP
0.009 - 0.013 (0.229 - 0.330)
NOTE 1 0.016 - 0.050 (0.406 - 1.270)
0.050 (1.270) TYP 0.014 - 0.019 (0.356 - 0.482) TYP
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
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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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Dimensions in inches (millimeters) unless otherwise noted.
G Package 28-Lead Plastic SSOP (0.209)
(LTC DWG # 05-08-1640)
0.397 - 0.407* (10.07 - 10.33) 0.068 - 0.078 (1.73 - 1.99) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
0.0256 (0.65) BSC 0.010 - 0.015 (0.25 - 0.38)
0.301 - 0.311 (7.65 - 7.90) 0.002 - 0.008 (0.05 - 0.21) 1 2 3 4 5 6 7 8 9 10 11 12 13 14
G28 SSOP 0694
NW Package 28-Lead PDIP (Wide 0.600)
(LTC DWG # 05-08-1520)
0.070 (1.778) TYP 28 27 26 25 24
1.455* (36.957) MAX 23 22 21 20 19 18 17 16 15
0.505 - 0.560* (12.827 - 14.224) 0.018 0.003 (0.457 0.076)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
N28 1197
SW Package 28-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
0.037 - 0.045 (0.940 - 1.143)
0.697 - 0.712* (17.70 - 18.08) 28 27 26 25 24 23 22 21 20 19 18 17 16 15
NOTE 1 0.004 - 0.012 (0.102 - 0.305)
0.394 - 0.419 (10.007 - 10.643)
1
2
3
4
5
6
7
8
9 10 11 12 13 14
S28 (WIDE) 0996
7
LT1342
TYPICAL APPLICATIO S
Operation Using 5V and 12V Power Supplies
V+ VCC 12V V + 0.1F 0.1F C1+ C1- DRIVER 1 OUT RX1 IN DRIVER 2 OUT TO LINE RX2 IN RX3 IN RX4 IN DRIVER 3 OUT RX5 IN ON/0FF = 5V 3V VL 1 2 3 4 5 6 7 8 9 10 11 12 13 14 0.1F
LT1342 * TA03
5V VCC
MOUSE 2 x 0.1F V+ LOGIC (1) DCD DSR RX RTS OPTICS V- TX CTS DTR (5) (9) RI
RELATED PARTS
PART NUMBER
LT1137A LTC1327 LT1330 LT1331 LTC1347 LTC1348
DESCRIPTION
3-DR/5-RX RS232 Transceiver 3-DR/5-RX RS562 Transceiver 3-DR/5-RX RS232 3-DR/5-RX RS232/RS562 Transceiver 3-DR/5-RX Micropower RS232 Transceiver 3-DR/5-RX RS232 Transceiver
8
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 q FAX: (408) 434-0507 q www.linear-tech.com
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28 LT1342 27 26 25 24 23 22 21 20 19 18 17 16 15
V- 0.1F 2 x 0.1F DRIVER 1 IN RX1 OUT DRIVER 2 IN RX2 OUT RX3 OUT RX4 OUT DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC TO LOGIC
Typical Mouse Driving Application
V+ 0.1F 5V VCC 1 2 3 4 5 6 7 8 9 LT1342 28 V - 27 26 25 DRIVER 1 IN 24 22 20 18 17 16 15 RX1 OUT 23 DRIVER 2 IN RX2 OUT 21 RX3 OUT RX4 OUT 19 DRIVER 3 IN RX5 OUT GND DRIVER DISABLE NC 2 x 0.1F LOGIC "0" LOGIC "0" 0.1F
DRIVER 1 OUT RX1 IN DRIVER 2 OUT RX2 IN RX3 IN
MOUSE DATA
RX4 IN 10 DRIVER 3 OUT 11 RX5 IN 12 ON/OFF 3V VL 13 14
LOGIC "1"
DB9
LT1342 * TA04
COMMENTS
15kV IEC-1000-4-2 ESD Protection 3.3V Operation 3V Logic Interface 5V RS232 or 3V RS562 Operation 5 Receivers Active in Shutdown True RS232 from 3V
1342fa LT/TP 1098 REV A 2K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1993

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