Recommendation for ByPass Capacitor in L6387E Mosfet Driver

[STuser2]

 I have seen recommendation for by pass capacitor to be 10 times the boot strap capacitor for Mosfet driver IC's. When i verified the schematics of mb1419-g431cbu6-c01_schematic 

The Boostrap capacitance value is 1uF but the By pass capacitance value is 470nF between VCC and Gnd. Request to please clarify.   

[AScha.3 · Accepted solution]

The 10V supply is not finished at the 470n cap....the 22u is next cap:

The 470n just close to the driver to prevent short spikes here.

So total capacity about 20x the bootstrap cap.

[STuser2]

That is very much clear now, Thank you very much.  Can you please help to clarify the below doubts it would be really helpful 

I have studied a simple formula for boot capacitor value in one of the websites which says it is 10 * Total Gate Charge of the Mosfet. The Mosfet used in the above schematic is stl180n6f7 and the total gate charge is 79.5nC, hence the bootstrap capacitance = 795nF => 0.795uF and they have selected 1uF, is my understanding correct?

Next most critical is selection of the Gate resistance as per the schematics they have selected 33Ohm, how? i want to change the MOSFET and also add one more in parallel then how do i calculate the gate resistor?  Can you please help with calculations?

[AScha.3]

> Can you please help with calculations?

Not much - as its almost a mix from ds info and personal experience and real testing and optimizing.

So nothing to tell some formulas and finished perfect.

Especially here you have an SMD 120A mosfet , that needs a PCB you have to create, maybe even metal core:

Try to learn and read the app notes and white papers from mosfet manufacturers (ST, Ti, Infineon, ...).

+

>how do i calculate the gate resistor?

Here for your stl180n6f7 see ds test condition:RG = 4.7 Ω .

As a first point of reference, to reach the values ​​in ds .

So needs at minimum an 2A or better 4A driver, and paralleling this will be difficult...switching 200 A ??

And no experience in building inverters ? (...good luck.)

What you wanna build ? (If its possible at all ..)