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LTC1686/LTC1687

52Mbps Precision Delay

RS485 Fail-Safe Transceivers

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Precision Propagation Delay Over Temperature:

Receiver/Driver: 18.5ns

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High Data Rate:

52Mbps

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Receiver/Driver: 500ps Typ

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–7V to 12V RS485 Input Common Mode Range

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Guaranteed Fail-Safe Operation Over the Entire

Common Mode Range

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High Input Resistance:

≥22k, Even When Unpowered

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Short-Circuit Protected

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Thermal Shutdown Protected

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Driver Maintains High Impedance in Three-State or

with Power Off

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Single 5V Supply

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Pin Compatible with LTC490/LTC491

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45dB CMRR at 26MHz

FEATURES

The LTC

full-duplex RS485 transceivers that can operate at data

rates as high as 52Mbps. The devices also meet the

requirements of RS422.

A unique architecture provides very stable propagation

delays and low skew over a wide common mode and

ambient temperature range.

The driver and receiver feature three-state outputs, with

disabled driver outputs maintaining high impedance over

the entire common mode range. A short-circuit feature

detects shorted outputs and substantially reduces driver

output current. A similar feature also protects the receiver

output from short circuits. Thermal shutdown circuitry

protects from excessive power dissipation.

The receiver has a fail-safe feature that guarantees a high

output state when the inputs are shorted or are left floating.

The LTC1686/LTC1687 RS485 transceivers guarantee

receiver fail-safe operation over the

entire common mode

range (– 7V to 12V). Receiver input resistance remains

≥22k when the device is unpowered or disabled.

The LTC1686/LTC1687 operate from a single 5V supply

and draw only 7mA of supply current.

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High Speed RS485/RS422 Full Duplex Transceivers

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Level Translator

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Backplane Transceiver

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STS-1/OC-1 Data Transceiver

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Signal Repeaters

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

10Mbps Data Pulse

400 Feet Category 5 UTP

1686/87 TA02

DRIVER INPUT

RECEIVER

INPUT

RECEIVER

OUTPUT

100ns/DIV

1V/DIV

2V/DIV

5V/DIV

CABLE DELAY

LTC1686/87 • TA01

100

Ω

100

Ω

100

Ω

100

Ω

LTC1686

LTC1686

R

D

R

D

3

2

7

8

6

5

400 FT OF CATEGORY 5 UTP

RECEIVER

DRIVER

RECEIVER

DRIVER