LTC1334_15 Datasheet, PDF (1/16 Pages) Linear Technology – Single 5V RS232/RS485 Multiprotocol Transceiver

FEATURES
s _{Four RS232 Transceivers or Two RS485}
Transceivers on One Chip
s _{Operates from a Single 5V Supply}
s _{Withstands Repeated ±10kV ESD Pulses}
s _{Uses Small Charge Pump Capacitors: 0.1µF}
s _{Low Supply Current: 8mA Typical}
s _{10µA Supply Current in Shutdown}
s _{Self-Testing Capability in Loopback Mode}
s _{Power-Up/Down Glitch-Free Outputs}
s _{Driver Maintains High Impedance in Three-State,}
Shutdown or with Power Off
s _{Thermal Shutdown Protection}
s _{Receiver Inputs Can Withstand ±25V}
U
APPLICATIO S
s _{Low Power RS485/RS422/RS232/EIA562 Interface}
s _{Software-Selectable Multiprotocol Interface Port}
s _{Cable Repeaters}
s _{Level Translators}
LTC1334
Single 5V RS232/RS485
Multiprotocol Transceiver
DESCRIPTIO
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.
TYPICAL APPLICATIO
2 1 28 27
3
LTC1334
V_CC1
26
5V
24
4
RX OUT
5
DR ENABLE ²³
6
22
DR IN
7
5V ²¹
5V ²⁰
DR IN ¹⁹
18
DR IN
17
RX OUT
16
RX OUT
15
8 _5V
9 _0V
11
10
13
12
14
120Ω
RS485 INTERFACE
120Ω
4000-FT 24-GAUGE TWISTED PAIR
RS232 INTERFACE
27 28 1 2
3
LTC1334
13
26
V_CC2
17
5V
12
RX OUT
18
11
DR ENABLE
10
19 _{DR IN}
9
5V
0V ⁸
4
5
6
7
14
21 _5V
20 _5V
24 _{RX OUT}
25
RX OUT
22
DR IN
23
DR IN
15
ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
LTC1334 • TA01
1