why isnt my bootstrap circuit working? why doesnt the signal at the gate go to zero? I'm buidling a class D amplifier and this is the output stage.Could anyone suggest a solution.

 

Hello, are you sure all of your components are fine? Did you test them individually?

 

Hello,

The ucc27517 is a low side driver.
It can not provide a bootstrap.
For a bootstrap you need a high side driver.

Bertus

 

Hello,

The ucc27517 is a low side driver.
It can not provide a bootstrap.
For a bootstrap you need a high side driver.

Bertus

I know, but im trying to implement an external bootstrap circuit with it, just to see if i can. Is there something wrong here? Thank you.

 

Your PWM input signal is common to both ICs. To make the boost work I think you would have to raise the PWM input to the high-side IC.

 

U8's input is referenced to Ground.
U7's input is referenced to V_Out. (not ground)
C14 is too small. Parallel with a 10uF.

 

View attachment 368532why isnt my bootstrap circuit working? why doesnt the signal at the gate go to zero? I'm buidling a class D amplifier and this is the output stage.Could anyone suggest a solution.

You mean "amplifier" I guess?

 

Probably it is not giving a signal because the driver is fully driven into saturation in one direction. AND, what is the purpose of the diode, capacitor, and resistor circuit not attached to other than "common"??
Please explain what you intend for this circuit to be doing. Is it intended to be a linear circuit, or a digital circuit??

 

In fact, WHAT are you trying to DO with that circuit?? It does not seem to even be an actual PWM power output scheme. Close, but not right.