5

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com

SP332_00_0260

TEST CIRCUITS

A

B

R

R

Figure 1. RS-485 Driver DC Test Load Circuit

C

L1

15pF

RO

A

B

A

B

DI

C

L2

R

DIFF

Figure 3. RS-485 Driver/Receiver Timing Test Circuit

500Ω

Output

Under

Test

Figure 4. RS-485 Driver Timing Test Load #2 Circuit

1KΩ

1KΩ

Receiver

Output

Test Point

Figure 2. Receiver Timing Test Load Circuit

SWITCHING WAVEFORMS

+3V

0V

DRIVER INPUT

A

B

DRIVER

OUTPUT

DIFFERENTIAL

OUTPUT

0V

1.5V

1.5V

Figure 5. RS-485 Driver Propagation Delays

RECEIVER OUT

1.5V

1.5V

OUTPUT

A – B

0V

0V

INPUT

≤

Figure 6. RS-485 Receiver Propagation Delays