IC-SP-06027 R1
8-3. IC destruction by external surge inputted to VS and VCC line (1)
Cause
The external surge on the VS and VCC line of the motor was put into IC. Because the
Zener voltage of the surge suppressor diode was higher than the maximum rating
voltage of IC, it did not protect IC.
The motor doesn't rotate by the over voltage destruction of IC.
Use the surge suppressor diode of the Zener voltage, which is lower than the
maximum rating voltage of IC.
Phenomenon
Countermeasure
8-4. IC destruction by external surge inputted to VS and VCC line (2)
Cause
The external surge on the VS and VCC line of the motor was put into IC. Because the
capacity of bypass capacitor for surge suppression was small, surge was not able to
be suppressed enough.
The motor doesn't rotate by the over voltage destruction of IC.
Use the bypass capacitor for surge suppression, which capacity should be enough to
suppress surge.
Phenomenon
Countermeasure
Small capacity case
Large capacity case
Fig. 8-3. Example to surge waveform by difference of capacity of bypass capacitor
8-5. IC destruction by external surge inputted to VS and VCC line (3)
Cause
The external surge on the VS and VCC line of the motor was put into IC. Because the
position of external parts for surge suppression on the motor populated board was
bad, surge was not able to be suppressed enough.
The motor doesn't rotate by the over voltage destruction of IC.
Bypass capacitor and Zener diode for surge suppression should be mounted close to
IC.
Phenomenon
Countermeasure
Far from IC
Close to IC
Fig. 8-4. Example to surge waveform by difference of the location on the board of bypass capacitor
-
33
-