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LTC1685

52Mbps, Precision Delay,

RS485 Fail-Safe Transceiver

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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 Receiver Operation Over the

Entire Common Mode Range

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High Receiver 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 LTC485

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45dB CMRR at 26MHz

FEATURES

The LTC

transceiver that can operate at data rates as high as 52Mbps.

The device also meets 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 LTC1685 RS485 transceiver guarantees receiver fail-

safe operation over the

entire common mode range (– 7V

to 12V). Input resistance will remain

≥22k when the device

is unpowered or disabled.

The LTC1685 operates from a single 5V supply and draws

only 7mA of supply current.

10Mbps Data Pulse

400ft Category 5 UTP

1685 TA02

DRIVER INPUT

RECEIVER

INPUT

RECEIVER

OUTPUT

100ns/DIV

1V/DIV

2V/DIV

5V/DIV

CABLE DELAY

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

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GND1

R

RO1

RE1

DE1

DI1

D

Rt

Rt

1685 TA01

GND2

R

RO2

RE2

DE2

DI2

D