UCC28951-Q1: During output rise time OUT-C and OUT-D gate pulse observed as below are above 50% duty.

yathavakannan viswa

Prodigy 70 points

Part Number: UCC28951-Q1
Other Parts Discussed in Thread: UCC28951, UCC28950

Tool/software:

Hello Team,

Vin- 380V

Vout-320V

Power- 1.2KW

During the startup condition, I have observed that the gate pulses for OUT-C and OUT-D exhibit a duty cycle that is either above or below 50%. Could you please explain why this behavior occurs and how to address it? Additionally, could this issue potentially lead to any failures in my board?

CH-1: OUT-C

CH-2: OUT-D

CH-3: Output rise time.

over 1 year ago

0 Mike O' over 1 year ago

TI__Guru* 86266 points

Hello,

This is under review and I will get back to you shortly.

Regards,

0 Mike O' over 1 year ago in reply to Mike O'

TI__Guru* 86266 points

Hello,

The Out C and Out D will appear to have > 50 % D and < 50% D when the converter immediately has a change in duty cycle. Both the UCC28950 and UCC28951 will exhibit this behavior under certain conditions. This is covered in more detail in the following two e2e threads.

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1400104/ucc28951-q1-during-output-rise-time-out-c-and-out-d-gate-pulse-observed-as-below-are-above-50-duty

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1121361/ucc28950-irregular-c-d-drive-output

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UCC28951-Q1: During output rise time OUT-C and OUT-D gate pulse observed as below are above 50% duty.