LT1280A/LT1281A
Low Power 5V RS232
Dual Driver/Receiver with
0.1µF Capacitors
DESCRIPTIO
The LT
®
1280A/LT1281A are dual RS232 driver/receiver
pairs with integral charge pump to generate RS232 volt-
age levels from a single 5V supply. These circuits feature
rugged bipolar design to provide operating fault tolerance
and ESD protection unmatched by competing CMOS
designs. Using only 0.1µF external capacitors, these cir-
cuits consume only 40mW of power, and can operate to
120kbaud even while driving heavy capacitive loads. New
ESD structures on the chip allow the LT1280A/LT1281A to
survive multiple
±10kV
strikes, eliminating the need for
costly TransZorbs
®
on the RS232 line pins. The LT1280A/
LT1281A are fully compliant with EIA RS232 standards.
Driver outputs are protected from overload, and can be
shorted to ground or up to
±30V
without damage. During
shutdown or power-off conditions, driver and receiver
outputs are in a high impedance state, allowing line
sharing.
The LT1281A is available in 16-pin DIP and SO packages.
The LT1280A is supplied in 18-pin DIP and SO packages
for applications which require shutdown.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TransZorb is a registered trademark of General Instruments, GSI
FEATURES
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10mA Max Supply Current
ESD Protection over
±10kV
Uses Small Capacitors: 0.1µF
120kBaud Operation for R
L
= 3k, C
L
= 2500pF
250kBaud Operation for R
L
= 3k, C
L
= 1000pF
Outputs Withstand
±30V
Without Damage
CMOS Comparable Low Power: 40mW
Operates from a Single 5V Supply
Rugged Bipolar Design
Outputs Assume a High Impedance State When Off
or Powered Down
Meets All RS232 Specifications
Available With or Without Shutdown
Absolutely No Latch-up
Available in SO Package
APPLICATI
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Portable Computers
Battery-Powered Systems
Power Supply Generator
Terminals
Modems
TYPICAL APPLICATI
+
0.1µF
2
4
LT1280A
17
3
5V INPUT
+
0.1µF
7
0.1µF
15
V
+
OUT
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
+
0.1µF
5
6
12
V
–
OUT
RS232 OUTPUT
LOGIC
INPUTS
11
13
8
14
5k
RS232 OUTPUT
RS232 INPUT
RECEIVER
OUTPUT
R
C
L
= 50pF
LOGIC
OUTPUTS
10
18
INPUT
9
5k
16
RS232 INPUT
LT1280A • TA02
ON/OFF
LT1280A • TA01
U
UO
+
UO
Output Waveforms
1
LINER [ LINEAR TECHNOLOGY ]
