INPUTS

RS-485/RS-422 Transceivers with Preemphasis

for High-Speed, Long-Distance Communication

_______________________________________________________________________________________

9

R

B

RO

ATE

A

R

0 DIFFERENTIAL

80%

20%

50%

Figure 9. Receiver Propagation Delay Test Circuit

Figure 10. Preemphasis Timing

RE

DI

DE

1k

RO

MAX3291

MAX3292

Figure 11. Time-to-Shutdown Test Circuit

Function Tables

DI

RE

DE

1

X

1

INPUTS

Z

0

OUTPUTS

Y

1

TRANSMITTING

1

0

0

X

1

High-Z

High-Z

High-Z and

SHUTDOWN

X

1

0

X

0

0

A-B

RE

DE

OUTPUT

RO

1

0

≤ -0.2V

0

X

1

High-Z and

SHUTDOWN

X

1

0

Open

0

X

≥ 0.2V

0

X

X = Don’t care

Z = High impedance

SHUTDOWN = Low-power shutdown; driver and receiver outputs are high impedance.

INPUTS

RECEIVING

High-Z

X

1

1