4

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

SP485R_00_072309

PIN FUNCTION

TEST CIRCUITS

A

B

R

R

Figure 2. Driver DC Test Load Circuit

C

L1

15pF

RO

A

B

A

B

DI

C

L2

R

L

Figure 4. RS-485 Driver/Receiver Timing Test

500Ω

Output

Under

Test

Figure 5. Driver Timing Test Load #2 Circuit

Figure 3. Receiver Timing Test Load Circuit

1kΩ

1kΩ

Receiver

Output

Test Point

Pin  - RO - Receiver Output

Pin 2 - RE - Receiver Output Enable Active LOW

Pin 3 - DE - Driver Output Enable Active HIGH

Pin 4 DI - Driver Input

Pin 5 - GND - Ground Connection

Pin 6 - A - Driver Output / Receiver input

Non-Inverting

Pin 7 - B - Driver Output / Receiver Input Inverting

Pin 8 - Vcc - Positive Supply 4.75V ≤ Vcc ≤ 5.25V

RECEIVER INPUT GRAPH

-7V

-3V

+6V

+12V

-0.6mA

+1.0mA

1 Unit Load

Maximum Input Current

versus voltage.

(Shaded region)

Standard SP485 Reciever

-7V

-3V

+6V

+12V

-60µA

+100µA

1/10 Unit Load

Maximum Input Current

versus voltage.

(Shaded region)

SP485R Reciever