Gate to source resistance

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Nimish

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How to determine the gate to source resistance for mosfets like irf840 and irfp460.


Is their any reason to put MOV across this resistances
 

Hi,
Usually a gate to source resistance is provided to prevent accidental turn-on due to noise or other factors or gate-to-drain internal capacitance (Miller capacitance). Normally I use 1k and it always works fine.
There is no need to put MOV across the resistance. Instead place a zener diode for providing gate-to-source protection from voltage spikes beyond the tolerable Vgs voltage.
Hope this helped.
Tahmid.
 

i am using driver IC to fire mosfet.Is it necessary to use back to back zener diodes from gate to source.
 

Which driver IC are you using?
Back to back zener diodes aren't necessary, but provide at least one zener and resistor for protection.
I usually use a 1k gate to source resistance and a 15v gate to source resistor.
Hope this helped.
Tahmid.
 

i use bi-directional TVS instead of a zener for protection because it is just as likely to get positive spikes as it is to get negative spikes.

it is small price to pay for increased reliability.

Mr.Cool
 
Hi, I am looking for someone who can explain how to calculate the following resistors in the picture below, taking into account the following.
N CHANNETL MOSFET IRFZ44N
P CHANNEL MOSFET IRF9510
batery lipo 2000mA 20c 11.1v
motor could pull upto 30A.
**broken link removed**

Thanks in advance.
Best regards.
 

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