Design guidelines for PCB schematic and layout

AN4189

18/23

Doc ID 023809 Rev 1

The system is working on PWM with a fast switching frequency of about 340 kHz which

causes the long copper wire to behave as a coil. To avoid this we recommend using the

ceramic capacitor to balance reactance. The ceramic capacitor must be placed as close as

possible, within 5 mm, to the related pins in order to minimize the inductive coil generated by

the copper wire.

Figure 26.

Solder decoupling capacitors as close as possible to their respective IC pins in order to

reduce the inductive coil (copper wire).

Figure 27.

Good and bad examples of amplifier bypassing

Place Vcc filter capacitors as close as possible to the related

pins, the ceramic capacitors on the bottom of the PCB

near the IC due to SMD mounting limitations.