UCC25630-1EVM-291: EVM issue

Hi Chentsu,

1. check the FB pin voltage and check if the opto-coupler is saturating. This would cause a delay in the transient response and result in heavy drop in the output voltage.

2. I would suggest checking the ISNS pin during startup and verify that the ISNS pin peak voltage is less than 4V during startup. You might be hitting the OCP threshold during startup.

Best Regards,
Ben Lough

Hi Ben,

Our customer is testing with TI's EVM without any modification.

1. From EVM user's guide, the EVM should can be loaded from 0A to 10A, am I right?

2. The loading is 14.5A, the EVM OVP, after a while, decrease loading to 10A but output voltage still can't recovery. Have to decrease loading to 0.03A, then output can recovery to 12V.

Is this normal at EVM?

Thank you.

Hi Chentsu,

1. Yes, the EVM is rated for 10A max. Can you send me a scope capture of the output voltage dropping to 0V during the load transient? Could you also check the voltage on the FB pin when the transient is applied? If the opto-coupler saturated, there is a delay for the opto-coupler to get out of saturation and respond to the transient event.

2. No, this is not normal. The EVM is supposed to be capable of startup into full load. Are you able to send me a scope capture of ISNS during heavy load startup?

Best Regards,
Ben Lough

Hi Chentsu,

Any update?

Best Regards,
Ben Lough

Hi Ben,

Customer will try a new EVM for this problem, I will feedback to you ASAP, thank you.

C.T.