8-6. IC destruction by line noise put into VCC (1)
Pulsed noise of a voltage that is lower than LVSD level was put into VCC line of IC. In
this case, IC repeats split-second LVSD operation. Then, IC will have the possibility
of causing the overheating destruction.
The motor doesn't rotate by the overheating destruction of IC.
(1) The noise that is put into motor Vcc line is removed by reviewing the power supply
circuit(inductance and so on of power cable).
(2) Suppress the noise by mounting the capacitor of enough capacity between Vcc
and GND pin of IC. That capacitor should be mounted close to Vcc-GND pin of IC.
Noise pulse width
Vcc voltage level : Vcc
Detect voltage of LVSD: LVSDON
Noise level : VccL
Vcc = 15V
Fig. 8-5. Example to pulsed noise on Vcc at IC destruction
8-7. IC destruction by line noise put into VCC (2)
The surge voltage that exceeds the maximum ratings of IC that was put into VCC pin
The motor doesn't rotate by the over voltage destruction of IC.
(1) Mount a bypass capacitor C1 close to pin of IC. It's effective to use a capacitor
that has excellent frequency characteristics, such as a ceramic capacitor, as a
bypass capacitor. As a guide, ones of around 1mF are recommended (The larger
the capacity, the more effective it is.).
(2) It is more effective to mount a surge suppression device such as bypass capacitor
C2 close to connector of motor populated board like figure 8-6.
Motor Power supply cable
Motor populated board
Fig. 8-6. Example to mount surge suppression devices