Hi,
I have a HV to 90V Half bridge dc-dc using UCC28250. During running normally we have approx. 90V on the output (loaded or unloaded). we have noticed that sometimes when the converter is disabled and enabled the output voltage is regulated to approx. 87V instead (both loaded and unloaded). When it is regulated to 90V it will be always around 90V as long as the converter is enabled and running. when the converter is enabled and had 87V output voltage, it will always be 87V loaded or unloaded and nicely regulated against load or line changes. This behaviour is not temperature dependant or load dependant. we think it is more to do with converter enable/ SS maybe/timing or a shift internally on the controller Vref?
Can you let us know what can cause this shift in voltage regulation? we have seen this behaviour in another converter with a different output voltage and power rating and similarly the regulated voltage change is around 3% again!
Please advice,
Omid
