LM22670: Switching frequency during softstart

Kuramochi Tadahiko

Guru 28715 points

Part Number: LM22670

Hi,

During softstart, is switching frequency set by RT or original value?

Best Regards,

Kuramochi

over 6 years ago

0 Arief Hernadi over 6 years ago

TI__Mastermind 23825 points

Hi,

During soft-start if SYNC signal is present, then it will switch based on your sync frequency. Also the synchronization works when the part is in CCM mode, therefore when you startup without load, the part will operate in DCM mode and it will not be at the frequency that you are synchronizing to.

The SYNC mode or RT mode is determined after the part is enabled. Therefore if you have a sync signal at startup and after startup you loss the sync signal, the part will switch at a default switching frequency of 500kHz

Thanks
-Arief

0 Kuramochi Tadahiko over 6 years ago in reply to Arief Hernadi

Guru 28715 points

Arief-san,

Thank you for your reply.

We are supposing to set switching frequency by RT.
Then, is switching frequency during soft-start based on RT?

Best Regards,
Kuramochi

0 Arief Hernadi over 6 years ago in reply to Kuramochi Tadahiko

TI__Mastermind 23825 points

Hi,

Yes that is correct.

Thanks
-Arief

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LM22670: Switching frequency during softstart