VIPER20ASP datasheet(17/25 Pages) STMICROELECTRONICS

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VIPer20/SP/DIP - VIPer20A/ASP/ADIP

Figure 23: Recommended Layout

LAYOUT CONSIDERATIONS

Some simple rules insure a correct running of

switching power supplies. They may be classified

into two categories:

- To minimize power loops: the way the switched

power current must be carefully analyzed and

the corresponding paths must present the

smallest possible inner loop area. This avoids

radiated EMC noises, conducted EMC noises

by magnetic coupling, and provides a better

efficiency by eliminating parasitic inductances,

especially on secondary side.

- To use different tracks for low level signals and

power ones. The interferences due to a mixing

of signal and power may result in instabilities

and/or anomalous behavior of the device in

case of violent power surge (Input overvoltages,

output short circuits...).

In case of VIPer, these rules apply as shown in

figure 23. The loops C1-T1-U1, C5-D2-T1, C7-D1-

T1 must be minimized. C6 must be as close as

possible to T1. The signal components C2, ISO1,

C3 and C4 use a dedicated track to be connected

directly to the source of the device.

VIPerXX0

13V

OSC

COMP

SOURCE

DRAIN

VDD

ISO1

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VIPER20ASP Fiches technique(PDF) 17 Page - STMicroelectronics