pwm deadtime control

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Hello:

I am using the tiny26 dual PWM output with the built in non-overlapping outputs (That is they never go high at the same time & there is a small deadtime delay between the transitions). My question--is it possible to adjust this deadtime---i'd like a slightly longer deadtime, right now it is approx 250ns. Would like to increase it to about 300ns. I don't think you can directly change this, but not sure.

I'd like to keep my pwm freq where it is (approx 24Khz). I just want to have a bit more deadtime. Any thoughts? If I MUST, I can lower the PWM freq a bit but don't want to.

Hoyt/

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I looked up the feature in the datasheet, and it appears that the intent is only to avoid both outputs being high at the same time.

Quote:
The non-overlap time is one prescaled clock cycle, and the high time is one cycle shorter than the low time.
The non-overlap time is generated by delaying the rising edge, i.e., the positive edge is one prescaled and one PCK cycle delayed and the negative edge is one PCK cycle delayed in the asynchronous mode. In the synchronous mode he positive edge is one prescaled and one CK cycle delayed and the negative edge is one CK cycle delayed. The high time is also one prescaled cycle shorter in the both operation modes.

I think you are out of luck since things are happening pretty fast with a compare match occurs. (I was thinking of changing the prescaler on-the-fly and then changing it back.)

If "lower the PWM freq a bit" includes cutting it in half, then try changing the prescaler. If not, I think you might be stuck. Putting a cap on the outputs would probably delay the turn-off as well as the turn-on.

Lee

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