LTC1334
Single 5V RS232/RS485
Multiprotocol Transceiver
FEATURES
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DESCRIPTIO
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Four RS232 Transceivers or Two RS485
Transceivers on One Chip
Operates from a Single 5V Supply
Withstands Repeated
±10kV
ESD Pulses
Uses Small Charge Pump Capacitors: 0.1µF
Low Supply Current: 8mA Typical
10µA Supply Current in Shutdown
Self-Testing Capability in Loopback Mode
Power-Up/Down Glitch-Free Outputs
Driver Maintains High Impedance in Three-State,
Shutdown or with Power Off
Thermal Shutdown Protection
Receiver Inputs Can Withstand
±25V
The LTC
®
1334 is a low power CMOS bidirectional trans-
ceiver featuring two reconfigurable interface ports. It can
be configured as two RS485 differential ports, as two dual
RS232 single-ended ports or as one RS485 differential
port and one dual RS232 single-ended port. An onboard
charge pump requires four 0.1µF capacitors to generate
boosted positive and negative supplies, allowing the RS232
drivers to meet the RS232
±5V
output swing requirement
with only a single 5V supply. A shutdown mode reduces
the I
CC
supply current to 10µA.
The RS232 transceivers are in full compliance with RS232
specifications. The RS485 transceivers are in full compli-
ance with RS485 and RS422 specifications. All interface
drivers feature short-circuit and thermal shutdown pro-
tection. An enable pin allows RS485 driver outputs to be
forced into high impedance, which is maintained even
when the outputs are forced beyond supply rails or power
is off. Both driver outputs and receiver inputs feature
±10kV
ESD protection. A loopback mode allows the driver
outputs to be connected back to the receiver inputs for
diagnostic self-test.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Low Power RS485/RS422/RS232/EIA562 Interface
Software-Selectable Multiprotocol Interface Port
Cable Repeaters
Level Translators
TYPICAL APPLICATIO
2
3
LTC1334
V
CC1
5V
RX OUT
DR ENABLE
DR IN
5V
5V
DR IN
DR IN
RX OUT
RX OUT
26
24
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16
15
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27
4
5
120Ω
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11
10
13
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14
5V
0V
RS485 INTERFACE
120Ω
13
12
11
10
5V
9
8
4
5
6
7
14
4000-FT 24-GAUGE TWISTED PAIR
RS232 INTERFACE
0V
ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
LTC1334 • TA01
U
27
28 1
LTC1334
2
3
26
17
18
19
21
20
24
25
22
23
15
V
CC2
5V
RX OUT
DR ENABLE
DR IN
5V
5V
RX OUT
RX OUT
DR IN
DR IN
U
U
1
LINER [ LINEAR TECHNOLOGY ]
