1

LTC1387

Single 5V RS232/RS485

Multiprotocol Transceiver

S

FEATURE

The LTC

rectional transceiver. It can be configured as an RS485

differential port or as two RS232 single-ended ports. An

onboard charge pump uses four 0.1

µF 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

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.

DESCRIPTIO

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Two RS232 Transceivers or One RS485 Transceiver

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Operates from a Single 5V Supply

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Guaranteed Receiver Output with Inputs

Floating or Shorted to Ground

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Logic Selectable Fast/Slow RS485 Driver Slew Rate

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Low Supply Current: 7mA Typical

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5

µA Supply Current in Shutdown

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Self-Testing Capability in Loopback Mode

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Separate Driver and Receiver Enable Controls

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Driver Maintains High Impedance in Three-State,

Shutdown or with Power Off

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Receiver Inputs Can Withstand

±25V

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Point-of-Sale Terminals

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Software Selectable Multiprotocol Interface Ports

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Low Power RS485/RS422/RS232/EIA562 Interface

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Cable Repeaters

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Level Translators

, LTC and LT are registered trademarks of Linear Technology Corporation.

APPLICATI

TYPICAL

9

DR ENABLE

14

SLEW

8

5V

13

5V

12

5V

18

3

18

3

19

20

5V

120

Ω

4

LTC1387

LTC1387 • TA01

RECOUT

RS485 INTERFACE

5

6

7

10

17

DR IN

15

11

4

9

LTC1387

RECOUT

15

DR ENABLE

DR IN

5

6

7

8

13

10

17

SLEW

14

5V

12

11

120

Ω

4000-FT 24-GAUGE TWISTED PAIR

5V

5V

ALL CAPACITORS: 0.1

µF MONOLITHIC CERAMIC TYPE

1

2

2

1

20

19

5V