UCC2897A: Does it ignore external SYNC signal at start-up

Tobias Ubostad

Part Number: UCC2897A

Tool/software:

Hello,

We have a product with the UCC2897A regulator, and are planning to implement in a multi-phase system with an external clock. We are a bit worried about start-up of the converter with a SYNC signal applied, which can in some cases lead to start-up issues with certain regulators.

Thus, we are wondering if the UCC2897A ignores the external SYNC signal at start-up, until some sort of a power good state is reached (and will only synchronize to the external SYNC signal then)?

Best regards,

Tobias

5 months ago

0 Hong Huang 5 months ago

TI__Guru 73595 points

Hi,

SYNC starts working after the device in sync starts switching. Due to parameter distribution devices in sync can start switching at different time .

0 Tobias Ubostad 5 months ago in reply to Hong Huang

Prodigy 30 points

Hello,

Thank you for the quick answer!

Still your answer was a bit unclear. UCC2897A will synchronize to an external SYNC signal when it starts switching, i.e. from the first switching period at startup?

So it does not ignore the external SYNC signal until the correct feedback/output voltage is reached?

Best regards,

Tobias

+1 Hong Huang 5 months ago in reply to Tobias Ubostad

TI__Guru 73595 points

Hi,

IC does not start switching until SS reaches 2.5V typical. This soft start time can be different due to parameter distributions. If IC does not start switching, SYNC signal cannot make sync.

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UCC2897A: Does it ignore external SYNC signal at start-up