I notice SOMETHING(C) when solenoid valve is triggered in high speed

Hi all,

Probe is connected at mosfet output(where solenoid is triggered) and below is what i got.

**broken link removed**

A - Rising & Falling interval is 80us [it off before on completely]
B - Rising & Falling interval is 1ms [it off after on completely]
C - Output remains ON for more than 120ms, it happens occasionally.

The ON in C is generated by solenoid, so can i presume C happens because of residue energy in solenoid inductor? correct me if i am wrong.

Whenever i trigger the solenoid in high speed as described in A(Rising & Falling interval is 80us) C happens occasionally, which it is a problem for me.
The controlling waveform is normal, C happens only when it is used to trigger inductive load.

So Any idea how to solve this please? thanks.

hi,
It appears that 'punch through' is occurring when switching the inductive load.

Look here: **broken link removed**

hi,
while going thru the provided link, please have a look on below..

The mosfet i use have turnontime 0.7ms(typ), 5ms(max) and turnofftime 0.04(typ), 5ms(max).
Told by a senior C happens becuase of the turnontime in A has out of spec, what do you think?

thanks.

Driver latchup. Usual fix is a "snubber" circuit (a resistor in series with a capacitor) across source and drain on the driver. Need some details on the solenoid to suggest some values.