10

Application Information

Bypassing and PC Board Layout

The HCPL-772X/072X optocouplers are extremely easy to use. No external interface circuitry is required because the

HCPL-772X/072X use high-speed CMOS IC technology allowing CMOS logic to be connected directly to the inputs

and outputs.

As shown in Figure 10, the only external components required for proper operation are two bypass capacitors. Ca-

pacitor values should be between 0.01 µF and 0.1

µF. For each capacitor, the total lead length between both ends of

the capacitor and the power-supply pins should not exceed 20 mm. Figure 11 illustrates the recommended printed

circuit board layout for the HPCL-772X/072X.

Figure 10. Recommended printed circuit board layout.

Figure 11. Recommended printed circuit board layout

Propagation Delay, Pulse-Width Distortion and Propagation Delay Skew

Propagation Delay is a figure of merit that describes how quickly a logic signal propagates through a system. The

amount of time required for the input signal to propagate to the output, causing the output to change from high to

low. See Figure 12.

Figure 12.

INPUT

tPLH

tPHL

OUTPUT

VI

VO

10%

90%

90%

10%

VOH

VOL

0 V

50%

5 V CMOS

2.5 V CMOS

HCPL-0710 fig 13

C1

C2

C1, C2 = 0.01 µF TO 0.1 µF

7

5

6

8

2

3

4

1

C1

C2

NC

NC

C1, C2 = 0.01 µF TO 0.1 µF