UCC2894: OCP or Output short circuit Protection using UCC2894D

Hi,

Thank you for the reply. 

cycle by cycle current limit means, the output voltage is reduced and the output current limited when OCP. 

Please suggest If I misunderstand. 

Thanks and Regards

Umamaheswararo 

Hi, 

Thank you. I also want to implement external circuit for short-circuit protection, Let us say if the rated current is 5A, once SC current reached to 7A, I want switch off my converter. Can you please guide me to implement the same. 

Thanks and Regards

Umamaheswararao

Hi,

If you need consistent 7A short circuit protection, then You will need to add a current sense circuit at the secondary side. You also need to have an independent bias circuit to bias the current sense circuit since when the converter output is shorted, and if no independent bias then the bias to the current sense and control is lost then you cannot get the current sense and control.

On the primary side, you need crow bar circuit ( such as thyrister) so the secondary current sense can turn on the thyrister to stop the converter until recycle the input power.

If you allow some variation on the 7A, then you can place current sense circuit on the primary side. If you test you will see the same short circuit on the secondary side will show different on the primary at different Vin. The higher the Vin the higher the primary peak current due to faster speed of the current peak at higher Vin. But you can design average current detection but responding speed may be a concern so you converter needs tolerate higher peak current for much longer time when get average current. 

The crow bar circuit is the same to cross say SS to pull down SS to help stop your converter no matter primary or secondary current sense and control.

Can you please make mind based on the above to see which is what you want, or something else?