Negative PWM

Carl 3 years ago in Master modules / MC4x updated by Doug Coutlee 3 years ago 2

Hi All,

We have a motor that requires a PWM negative signal. Using an MC42, anyone ever done this? if so, how?

It sounds as if you need a low-side PWM to give a signal to a device that has an internal pull-up ?

The PWM out HS+LS has a low-side, but there are two problems to using it. One is the PMW out HS+LS open load detection,  and one is the reverse feed detection. 

Here is a related discussion: https://forum.iqan.se/en/communities/1/topics/2201-mc4x-option-to-disable-open-load-detect-on-pwm-out-hsls


We had the same issue and found that using a SS relay was the correct solution for us. Just drive the coil of your SS relay with the HS+LS PWM out and connect your motor control through the relay contacts. Should do the trick.