[Diy_efi] good PWM freq. for peak and hold driver

[Kent Martin]

On further testing it would seem that 5 Khz would be to slow.
I used a 20 Khz PWM at 85 % to obtain a 1amp hold current.
The peak on time was 1.6 mS and max current was about 3 amps.
When the peak period ended there was a 34 uS low period due to 
the switch over between the modes and the current dropped
by about 1 amp in this period. This would make it difficult to operate
were the frequency only 5 Khz due to the longer low periods.
You might consider using a faster frequency, and will probably need
a cro and a small current measuring resistor (about 0.05 Ohms) to 
adjust it until you get the correct peak and hold currents.

Kent.

> > I want to use a pwm drive for my injectors, and would like to
> > know what frequency to run it at. I was thinking around 5 KHz.
> > The MegaSquirt does the PWM current limit, but I didn't see a
> > mention of the freq. anywhere, including the source code.
> > -Les
> > 
> > 
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