Does anyone know if the two channels of pwm on an 877A can be delayed from each other, or otherwise run at the same frequency , but not fire at the same time.?
i'm working on a boost converter with two fets , that i would like to fire at different times, but run at the same frequency.

 

Due to the fact that there is only one timer2 and one PR2 register, I don't see how you could get to trigger at different times unless you invert one of the outputs (or P channel fet) so one fires at the beginning of the period and the other toward the end. If you switch to the 887 then having an inverted output is available as standard.

Mike.

 

Thanks for your input .
i suppose a simple AND gate may provide the needed delay clocked by the osc clock anded with the pwm output might work
i just want to give the system time to recover and maybe catch the upswing of the oscillation from the coils.

 

A really crazy idea would be to have one of the PWM modules trigger an interrupt that changes a different output pin. The IRQ latency providing the necessary delay. Whether this would work really depends on the PWM frequency.

Mike.

 

I used several inverters and it seems to work
i havnt scoped the delay yet