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Jeremy Towers

PWM polarity

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Hi I have a General Purpose PWM configured on Aux 5 of a G4 Xtreme. I understand this output can be used for High or Low drive and High or Low polarity. I would like to have High polarity to trigger a Mosfet switch, but it appears that when configured as a PWM neither the Drive nor polarity can be changed. Is that correct? Thanks Jeremy

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Hi Jeremy,

The ECU unfortunately can not high side drive with a PWM signal.

There is no setting for polarity as this is not really needed with GP PWM. If you want to invert the polarity of a 30% PWM signal you simply subtract 30% from 100% to get the percentage that gives the same waveform of opposite polarity.

Regards,

Phil

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Thanks Phil But I beg to differ about the polarity. I don't have a problem setting 20% as 80% and 30% as 70% etc, but I want to be able to set a condition to turn the PWM off. Unfortunately when conditions are not met the output goes high, which in my case is fully ON. Hence there is no way to turn the output off? Regards Jeremy

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Jeremy  Have you looked at some MOSFET drivers?

Take the PWM output from the ECU through a inverting driver and drive your MOSFET from that device..

I have used the MC34151 device in the past for driving light regulation on LightForce driving lights (way back before they bought out their regulators)

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Hi Jeremy.

Rod is on the money with that one.  I have had a look at the datasheet of this chip and it would work very well for your purpose.  Super easy to understand the logic, and has 2 in/outs... So you could do another PWM signal too ;)

For your info, attached is a small block diagram that I looked at.

Jurgen

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