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LM5164: DCM and light load

user5827790
Prodigy 70 points
Part Number: LM5164

Hi team,

1, Why is the input FB ripple greater than 20mV? Is 15mV ok？

2, LM5164 has diode emulation mode, how this mode is controlled specifically? Is it still controlled by VFB in DCM mode？

3，What are the conditions and specific operating modes for entering PSM?

4，What should I do if I want to reduce the output voltage overshoot during the dynamic process？

best regards

  • 0
    TI__Mastermind 27030 points

    Hi

    1. 15mV is not recoomend, smaller ripple will cause larger jitter of duty.

    2. DEM mode is control by sensing the current go through syncrhnous fet , the output is still controlled by VFB in DCM mode

    3，What is PSM for? power save mode?

    4，What the ripple jection you used for? normally increase the output cap and increase the frequency can help on the dynamic process. 

  • 0 in reply to Daniel Li14
    Prodigy 70 points

    3, Pulse skipping mode. When Vin is fixed, LM5164 will have a constant on time. But in DCM, we need a on time less than this constant on time. How will the chip work at this condition? Will it increase the off time？

    4, TYPE-3, how to adjust ripple jection circuit to make overshoot smaller？

  • 0 in reply to user5827790
    TI__Mastermind 27030 points

    Hi

    3. Yes, in light mode, the device will increase the off time to make it work at low frequency

    4. for type 3, the smaller Cb will have better transient performance.

    Thanks