LT1342
5V RS232 Transceiver with
3V Logic Interface
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
s
ESD Protection Over
卤10kV
3V Logic Interface
Uses Small Capacitors: 0.1碌F, 0.2碌F
1碌A Supply Current in Shutdown
Low Power Driver Disable Operating Mode
Pin Compatible with LT1137A
120kBaud Operation for R
L
= 3k, C
L
= 2500pF
250kBaud Operation for R
L
= 3k, C
L
= 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
庐
1342 is an advanced low power three-driver, five-
receiver 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
卤10kV
strikes, eliminating the need for
costly TransZorbs
庐
on the RS232 line pins.
The LT1342 is fully compliant with all EIA RS232 specifi-
cations 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
s
s
S
Notebook Computers
Palmtop Computers
TYPICAL APPLICATI
V
+
0.1碌F
2
脳
0.1碌F
DRIVER 1 OUT
RX1 IN
DRIVER 2 OUT
TO LINE
RX2 IN
RX3 IN
RX4 IN
DRIVER 3 OUT
RX5 IN
ON/OFF
3V V
L
5V V
CC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LT1342
28 V
鈥?/div>
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 鈥?TA01
0.1碌F
2
脳
0.1碌F
RECEIVER
OUTPUT
V
L
= 3V
C
L
= 50pF
DRIVER
R
OUTPUT
R
L
= 3k
C
L
= 2500pF
TO 3V LOGIC
INPUT
U
Output Waveforms
LT1342 鈥?TA02
UO
UO
1
1
2
3
4
5
6
7
8
