Mosfet gate driver problem

[Manchested]

When using gate driver for npn high side switch, is there any way to improve the switch off falling time so that it can be symmetrical to the rising time?

 

[leo_o2]

You need to increase sinking capability for gate driver to reduce switching off time.
However, it is hard to be symmetrical because turn-on time only needs to charge from 0V to NMOS's Vth and turn-off time needs to discharge from VDD to Vth.
For example, VDD=5V, Vth=0.7V, you can see the difference.

 

[goldsmith]

Dear friend
Hi
For gate drive, you can use from gate driver ic or use totem pole driver circuit, it is very fast to mosfet or igbt control

 

[Manchested]

hi,
I've found totem pole two configurations.
one with npn at the top and pnp at the bottom
another one with one npn stacked on another npn
Could you tell me what are their differences??

 

[goldsmith]

in your aim , first one , because in second model , you can not turn on top npn as well as (that will work at linear region near saturation) , but first seems better . but you can test both of them and find difference between them. both of them can work good but first is my suggestion to you!
Best wishes
Goldsmith

 

[leekc_84]

What I saw is p-mosfet at top, and n-mosfet at bottom, like complementary configuration.

When designing totem pole MOSFET switch, what should we pay attention, e.g. Vth, external passive?

 

[goldsmith]

Hi
In first step , performance frequency of mosfets are important (ciss should become low) . and in second step the out put current that you need is essential ( for driving) . but i think totem pole with BJT arrangement is better for this aim. because you can control out put current (easily )(with series resistor with base) and you can find high frequency bjt s in low price.
I hope being helpful for you!
Best lucks
Goldsmith