LM25149: Dual-random spread spectrum at light load

R.Fukunaga

Expert 2675 points

Part Number: LM25149

Hi all,

I would like to ask you DRSS function at light load.

Is it disabled only when an external clock is applied to the PFM/SYNC pin?

Is it correct that DRSS works in PFM mode at light load?

Please let me know.

Kind regards.

Ryusuke

+1 Orlando Murray over 2 years ago

Hi Ryusuke,

In PFM mode the frequency can be reduced greatly. See figure 9-22 from the datasheet.

The PFM operation mode is different, it does not use the oscillator clock and really the frequency depends on the load.

When the load is at a point where there's more CCM pulses, then DRSS is enabled.

Hope this helps,

-Orlando

0 R.Fukunaga over 2 years ago in reply to Orlando Murray

Expert 2675 points

Hi Orlando,

Thank you for your reply.

Let me check, just in case.

DRSS function is enable in FPWM mode?

Best Regards,

Ryusuke

+1 Orlando Murray over 2 years ago in reply to R.Fukunaga

Hi Ryusuke,

Yes, DRSS is enabled in FPWM.

-Orlando

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