Drive high side N-channel Mosfets

[m8911]

Hi,

I've been trying to drive the high side N-channel Mosfets of H-bridge using a totem pole configuration as in the picture but it's not working..

I searched in the forum and the given solution is to use a mosfet driver but the problem is that i need to do it using the totem pole config and using N-channel mosfets

can someone tell me how i can modify the above circuit to make it work..

 

[keith1200rs]

I cannot access the picture. Try uploading it to the EDAboard.

Keith.

 

[alexan_e]

Me too, I get a 403 - Forbidden message when I click the image link

 

[m8911]

plz try again, i uploaded it on the forum

 

[alexan_e]

Assuming that you will be constantly switching the H bridge mosfets you can use the bootstrap solution

 

[m8911]

thanks for the reply alexan_e

so the circuit you provided above is for the high side mosfets only? should i connect the output from the optocoupler to Q1(G)? how do i choose the voltage for D1(A)?

 

[alexan_e]

this is supposed to be a high side only and that is why the load is connected between the source and gnd.
You should remove the load and connect the drain of the lower side mosfet in its place.

The optocoupler output transistor can replace the Q1.
The D1 voltage is the same voltage that powers the bridge, it is 15v in your case and assuming that your mosfet has a max Vgs of 20v there will be no problem with 15v.
Q5 is just a pre driver of the totem pole , if you want to use a different design then you can remove it.

Alex