Checking Mosfets

[pier1]

Hello,

While checking the N Channel Mosfet. I put the multimeter in the Beep mode (continuity mode)

Probing the -ve probe at the Mosfet Drain (tab), the +ve probe at the Source pin - the multimeter reads 500+ ohms which is the body diode I think.

Then

Still probing the -Ve on the Drain
I touch the +ve probe on the gate for a moment and then probe it back on the source it shows a dead short.

I don't know why this happens. Any body knows about this, please share.

The mosfet I used is FDD13AN0 from Fairchild initially

I tried the same with the:
BUK919 from NXP
NTD5867NL and a couple more and all show the same.

Regards
Pier

 

[audioguru2]

Your multimeter turned on the Mosfet and charged the gate-source capacitance that kept it turned on. The gate-source has an extremely low leakage current so the gate charge might last for a fairly long time.

 

[pier1]

Thanks AG for the reply.
Any ways of measuring this gate charge ?

Regards,
Pier

 

[Hero999]

Why bother measuring it?

It's easier to read the datasheet.

 

[zoro222]

i agree with audioguru and if you touched the gate and -ve the part will read hi resistance