LTC1348
3.3V/5V Low Power RS232
3-Driver/5-Receiver Transceiver
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DESCRIPTIO
FEATURES
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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
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APPLICATI
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Notebook Computers
Palmtop Computers
Printers
Portable Instruments
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, ICC 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 impedance 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 operates 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.
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TYPICAL APPLICATI
Supply Current
3-Drivers/5-Receivers with Shutdown
2
LTC1348
27
3
VCC
C1
0.1µF
DR 1 OUT
RX1 IN
DR 2 OUT
RX2 IN
RX3 IN
RX4 IN
DR 3 OUT
RX5 IN
1.6
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
16
14
15
C3
0.1µF
26
DR 1 IN
RX1 OUT
DR 2 IN
RX2 OUT
RX3 OUT
C4
0.1µF
1.6
1.4
V–
1.4
1.2
1.0
RX5 OUT
DREN
0.8
RXEN
0.8
VCC = 3.3V
0.6
0.4
VCC = 3.3V
OR 5V
0.2
0
–40
1.0
VCC = 5V
RX4 OUT
DR 3 IN
1.2
QUIESCENT
CURRENT
0.6
SHUTDOWN
CURRENT
0.4
SHUTDOWN CURRENT (µA)
C2
0.1µF
28
1
SUPPLY CURRENT (mA)
V+
C5
0.1µF
0.2
0
–20
0
40
20
TEMPERATURE (˚C)
60
80
LT1348 •TA02
GND
LT1348 • TA01
1
