Can i use 1k resistor on each gates?

Khaleef

Joined Mar 22, 2017
78
Following a YouTube video of a Mosfet Spot Welder, a 1k resistor was was tied to 10 paralleled Mosfets which works well in the video.

Building the same, a friend suggests I use individual 10ohms resistor on each Mosfet gate but I have a lot of 1k resistors.

Can i use the 1k on each of the 10 mosfet?

Ian0

Joined Aug 7, 2020
4,068
Following a YouTube video of a Mosfet Spot Welder, a 1k resistor was was tied to 10 paralleled Mosfets which works well in the video.

Building the same, a friend suggests I use individual 10ohms resistor on each Mosfet gate but I have a lot of 1k resistors.

Can i use the 1k on each of the 10 mosfet?
Depends on the MOSFET gate capacitance and the switching frequency.
Work out the time constant (1k x gate capacitance).
The MOSFET will dissipate a quarter of the load for the duration of the time constant twice every switching cycle, in addition to its resistive losses.
so P(MOSFET) ≈ ½P(load) * f * time constant + I(load) * Rds(on)

• click_here and Khaleef

Khaleef

Joined Mar 22, 2017
78
Depends on the MOSFET gate capacitance and the switching frequency.
Work out the time constant (1k x gate capacitance).
The MOSFET will dissipate a quarter of the load for the duration of the time constant twice every switching cycle, in addition to its resistive losses.
so P(MOSFET) ≈ ½P(load) * f * time constant + I(load) * Rds(on)
Thanks Ian0

The mosfet I use is IRF3713. I really dont know much of the Mosfet capacitance calculation.

Ian0

Joined Aug 7, 2020
4,068
Thanks Ian0

The mosfet I use is IRF3713. I really dont know much of the Mosfet capacitance calculation.
Page 1 of the datasheet "Input capacitance" 5890pF
It's only an approximation, but it gives good idea how warm it will get.