LTC1387_15 Datasheet, PDF (1/12 Pages) Linear Technology – Single 5V RS232/RS485 Multiprotocol Transceiver

LTC1387
Single 5V RS232/RS485
Multiprotocol Transceiver
FEATURES
s _{Two RS232 Transceivers or One RS485 Transceiver}
s _{Operates from a Single 5V Supply}
s _{Guaranteed Receiver Output with Inputs}
Floating or Shorted to Ground
s _{Logic Selectable Fast/Slow RS485 Driver Slew Rate}
s _{Low Supply Current: 7mA Typical}
s _{5µA Supply Current in Shutdown}
s _{Self-Testing Capability in Loopback Mode}
s _{Separate Driver and Receiver Enable Controls}
s _{Driver Maintains High Impedance in Three-State,}
Shutdown or with Power Off
s _{Receiver Inputs Can Withstand ±25V}
U
APPLICATIONS
s _{Point-of-Sale Terminals}
s _{Software Selectable Multiprotocol Interface Ports}
s _{Low Power RS485/RS422/RS232/EIA562 Interface}
s _{Cable Repeaters}
s _{Level Translators}
DESCRIPTIO
The LTC^®1387 is a low power reconfigurable CMOS bidi-
rectional transceiver. It can be configured as an RS485
differential port or as two RS232 single-ended ports. An
onboard charge pump uses four 0.1µF capacitors to
generate boosted positive and negative supplies, allowing
the RS232 drivers to meet ±5V output swing require-
ments with only a single 5V supply. A shutdown mode
reduces the I_CC supply current to 5µA.
The RS232 transceivers are in full compliance with RS232
specification. The RS485 transceiver is in full compliance
with RS485 and RS422 specifications. The RS485 re-
ceiver assumes a known output state when the inputs are
floating or shorted to ground. All interface drivers feature
short-circuit and thermal shutdown protection. 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 the power is off. A loop back
mode allows the driver outputs to be connected back to the
receiver inputs for diagnostic self-test.
The LTC1387 is available in 20-pin plastic SSOP and SW
packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
2 1 20 19
3
LTC1387
V_CC1
18
5V
19 20 1 2
3
LTC1387
18
V_CC2
5V
17
RECOUT
DR IN ¹⁵
SLEW ¹⁴
DR ENABLE ⁹
5V ¹²
11
4
4
5
RS485 INTERFACE
5
120Ω
6
120Ω
6
7
4000-FT 24-GAUGE TWISTED PAIR
7
8 _5V
13 _5V
10
8
5V
5V ¹³
10
ALL CAPACITORS: 0.1µF MONOLITHIC CERAMIC TYPE
17
RECOUT
15
DR IN
14 _SLEW
9 _{DR ENABLE}
12 _5V
11
LTC1387 • TA01
1