ElecDesigner
Member level 5
Hi,
I am testing a Flyback convertor that uses the LM5021 IC.
I have an issue where at some load / Vin combinations every other PWM pulse is a different width. I am using the IC variant that allows 50% duty cycle max and as far as I can see , for example, one pulse might be close to 50%, the next 30%, then 50% and so on.
I wouldn't have thought it would be the Voltage feedback loop but I have slugged that anyhow, with no effect. I am not an expert but it sounds like the sort of thing you might get with Duty Cycles above 50% (requiring slope comp to fix it).
As the controller I am using is limiting the Duty cycle to less than 50% I am confused as to why this is happening.
I am testing a Flyback convertor that uses the LM5021 IC.
I have an issue where at some load / Vin combinations every other PWM pulse is a different width. I am using the IC variant that allows 50% duty cycle max and as far as I can see , for example, one pulse might be close to 50%, the next 30%, then 50% and so on.
I wouldn't have thought it would be the Voltage feedback loop but I have slugged that anyhow, with no effect. I am not an expert but it sounds like the sort of thing you might get with Duty Cycles above 50% (requiring slope comp to fix it).
As the controller I am using is limiting the Duty cycle to less than 50% I am confused as to why this is happening.