As per the suggestions I received in the last thread, I have come up with a new version of my h bridge. The bridge itself can be found here:
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and the input section is here:
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I would once again appreciate any feedback you would like to offer.
Briefly the changes I made are:
- Switching of the FETS now done through a push-pull setup. By my calculations the 68 ohm resistor should dissipate about 3/4 of a watt
- Deadtime. I calculated the required deadtime based upon the input capacitance listed in the data sheet. I would guess the output capacitance may have been more appropriate, but chose the input as it was the larger of the two. Discharge time was calculated using RxC through the 68 ohm resistor. I then doubled that number and use it as my deadtime. I hope that was right??
Incidentally, should I drive the P chan FETS from the first inverter, rather than from the n chan FETS. I'm thinking that the p chans may stay on too long, as they will not switch off until the n chans are almost fully off?
Many thanks again
Big Matt