AN280

Power supply filtering

Doc ID 1703 Rev 3

7/15

3

Power supply filtering

To reduce the effect of the wiring inductance a good high frequency capacitor can be placed

on the board near the bridge circuit to absorb the small amount of inductive energy in the

leads. It should be noted that this capacitor is usually required in addition to an electrolytic

capacitor, which has poor performance at high frequencies.

3.1

Operating voltages

Figure 5.

Supply voltage

Figure 5 and Figure 6 show the spike on the power supply pin of the L6203 and the output

pins when the bridge was disabled. These waveforms were present when the device was

mounted on a printed circuit board where reasonable care was taken in the layout. When a

0.2 µF polyester capacitor was connected between the supply and ground pin of the L6203

the voltage spike on the power supply was significantly reduced, as shown in Figure 7.

Figure 6.

AM15172v1

AM15173v1