LMR38010: Spread Spectrum at light load

R.Fukunaga

Expert 1225 points

Part Number: LMR38010

Hi all

I would like to know Spread Spectrum function at light load.

The device enters PFM mode at light load.

I understand switching frequency is lower in PFM mode.

・Is Spread Spectrum functioning in PFM mode?

・Is Spread Spectrum effective for noise reduction at light load?

Please let me know.

Kind regards.

Ryusuke

over 1 year ago

0 Elena Gao over 1 year ago

TI__Genius 13735 points

Hi, Ryusuke,

No, SS function is working in FPWM mode with frequency , not in PFM mode.

Elena

0 R.Fukunaga over 1 year ago in reply to Elena Gao

Expert 1225 points

Hi, Elena,

Thank you for your reply.

Are all device of power supply with PFM mode the same?

Not is it just this device?

Ryusuke

+1 Elena Gao over 1 year ago in reply to R.Fukunaga

TI__Genius 13735 points

Yes. all the same. this is common.

0 R.Fukunaga over 1 year ago in reply to Elena Gao

Expert 1225 points

Thank you very much!

Ryusuke

0 R.Fukunaga over 1 year ago in reply to R.Fukunaga

Expert 1225 points

Let me check, just in case.

Is DRSS(Dual Random Spread Specture) function the same?

Is it not working in PFM mode?

Ryusuke

0 Elena Gao over 1 year ago in reply to R.Fukunaga

TI__Genius 13735 points

I copy one part from another device as below. please see this detail

0 R.Fukunaga over 1 year ago in reply to Elena Gao

Expert 1225 points

Hi Elena,

SS function is only available while the clock of the device is free running at their natural frequency.

Is it DRSS function the same?

Best Regards.

Ryusuke

+1 Elena Gao over 1 year ago in reply to R.Fukunaga

TI__Genius 13735 points

Hi, Ryusuke,

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

When the load increase, until to CCM pulses, then DRSS is enabled.

Elena

Power management

Power management forum

LMR38010: Spread Spectrum at light load