LTC1348
3.3V/5V Low Power RS232
3-Driver/5-Receiver Transceiver
FEATURES
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DESCRIPTIO
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Low Supply Current: 600µA at 3.3V
Supply Current in Shutdown: 0.2µA
Supply Current in Receiver Alive Mode: 15µA
ESD Protection over
±10kV
Operates from a Single 3V to 5.5V Supply
Operates to 120kBaud with 0.1µF Flying Capacitors
Three-State Outputs Are High Impedance When Off
Output Overvoltage Does Not Force Current
Back into Supplies
RS232 I/O Lines Can Be Forced to
±25V
Without Damage
Flowthrough Architecture
The LTC
®
1348 is a 3-driver/5-receiver RS232 transceiver
with very low supply current. The charge pump only
requires five 0.1µF capacitors. The LTC1348 provides full
RS232 output levels when operated over a wide supply
range of 3V to 5.5V
The transceiver operates in one of four modes: Normal,
Receiver Disable, Receiver Alive and Shutdown. In Normal
or Receiver Disable mode, I
CC
is only 600µA at 3.3V and
800µA at 5V in the no load condition. In Shutdown mode,
the supply current is further reduced to 0.2µA. In Receiver
Alive mode, all five receivers are kept alive and the supply
current is 15µA. All RS232 outputs assume a high imped-
ance state in Shutdown or Receiver Alive mode or with the
power off. The receiver outputs assume a high impedance
state in Receiver Disable or with the power off.
The LTC1348 is fully compliant with all data rate and
overvoltage RS232 specifications. The transceiver oper-
ates up to 120kbaud with all drivers loaded with 1000pF,
3kΩ. Both driver outputs and receiver inputs can be forced
to
±25V
without damage and can survive multiple
±10kV
ESD strikes.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATI
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Notebook Computers
Palmtop Computers
Printers
Portable Instruments
TYPICAL APPLICATI
V
+
C5
0.1µF
C2
0.1µF
V
CC
C1
0.1µF
DR 1 OUT
RX1 IN
DR 2 OUT
RX2 IN
RX3 IN
RX4 IN
DR 3 OUT
RX5 IN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LTC1348
3-Drivers/5-Receivers with Shutdown
28
27
26
25
24
23
22
21
20
19
18
17
16
15
C3
0.1µF
DR 1 IN
RX1 OUT
DR 2 IN
RX2 OUT
RX3 OUT
RX4 OUT
DR 3 IN
RX5 OUT
DREN
RXEN
GND
LT1348 • TA01
V
–
C4
0.1µF
SUPPLY CURRENT (mA)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
–40
–20
V
CC
= 5V
V
CC
= 3.3V
V
CC
= 3.3V
OR 5V
SHUTDOWN
CURRENT
QUIESCENT
CURRENT
U
Supply Current
1.6
1.4
SHUTDOWN CURRENT (µA)
UO
UO
1.2
1.0
0.8
0.6
0.4
0.2
0
40
20
TEMPERATURE (˚C)
0
60
80
LT1348 •TA02
1
LINER [ LINEAR TECHNOLOGY ]
