LT1537
Advanced Low Power
5V RS232 Transceiver with
Small Capacitors
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DESCRIPTIO
FEATURES
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Low Cost
Uses Small Capacitors: 0.1µF, 0.2µF
1µA Supply Current in Shutdown
120kBaud Operation for RL = 3k, CL = 2500pF
250kBaud Operation for RL = 3k, CL = 1000pF
CMOS Comparable Low Power: 40mW
Operates from a Single 5V Supply
Easy PC Layout: Flow-through Architecture
Rugged Bipolar Design
Outputs Assume a High Impedance State When Off
or Powered Down
Improved Protection: RS232 I/O Lines Can Be Forced
to ±25V Without Damage
Output Overvoltage Does Not Force Current Back
into Supplies
Absolutely No Latch-Up
Available in SO Package
The LT ®1537 is a three-driver, five-receiver RS232 transceiver, pin compatible with the LT1137A, offering performance improvements and two shutdown modes. The
LT1537’s charge pump is designed for extended compliance and can deliver over 35mA of load current. Supply
current is typically 8mA, competitive with similar CMOS
devices. An advanced driver output stage operates up to
250kbaud while driving heavy capacitive loads.
The LT1537 is fully compliant with all RS232 specifications. Special bipolar construction techniques protect the
drivers and receivers beyond the fault conditions stipulated for RS232. Driver outputs and receiver inputs can be
shorted to ±25V without damaging the device or the
power supply generator. In addition, the RS232 I/O pins
are resilient to multiple ±5kV ESD strikes.
The transceiver has two shutdown modes. One mode
disables the drivers and the charge pump, the other shuts
down all circuitry. While shut down, the drivers and
receivers assume high impedance output states.
UO
APPLICATI
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Notebook Computers
Palmtop Computers
, LTC and LT are registered trademarks of Linear Technology Corporation.
UO
TYPICAL APPLICATI
2 × 0.1µF
5V VCC
LT1537
27
3
RX IN
DRIVER OUT
RX IN
RX IN
RX IN
DRIVER OUT
RX IN
ON/OFF = 5V
26
4
+
DRIVER OUT
TO
LINE
2
Output Waveforms
V–
25
5
24
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23
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22
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15
+
+
0.1µF
28
1
2 × 0.1µF
+
V+
0.1µF
RECEIVER
OUTPUT
CL = 50pF
DRIVER IN
RX OUT
R
DRIVER IN
RX OUT
RX OUT
TO LOGIC
DRIVER
OUTPUT
RL = 3k
CL = 2500pF
RX OUT
DRIVER IN
INPUT
RX OUT
GND
DRIVER
DISABLE
LT1537 • TA02
LT1537 • TA01
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