Datasheet

1
LT1280A/LT1281A
Low Power 5V RS232
Dual Driver/Receiver with
0.1µF Capacitors
R
Output Waveforms
LT1280A • TA02
DRIVER
OUTPUT
R
L
= 3k
C
L
= 2500pF
RECEIVER
OUTPUT
C
L
= 50pF
INPUT
S
F
EA
T
U
RE
D
U
ESCRIPTIO
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
Portable Computers
Battery-Powered Systems
Power Supply Generator
Terminals
Modems
U
S
A
O
PP
L
IC
AT
I
U
A
O
PP
L
IC
AT
ITY
P
I
CA
L
5k
5k
0.1µF
0.1µF
0.1µF
0.1µF
LOGIC
INPUTS
LOGIC
OUTPUTS
ON/OFF
18
10
13
11
12
6
5
4
2
16
9
14
8
15
7
3
17
5V INPUT
V
+
OUT
V
OUT
RS232 OUTPUT
RS232 OUTPUT
RS232 INPUT
RS232 INPUT
LT1280A • TA01
LT1280A
+
+
+
+
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

Summary of content (8 pages)