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LMR23610: DCDC LMR23610 light mode work frequency

huanghai liu
Prodigy 10 points
Part Number: LMR23610

LMR23610 will work on PFM mode when light load.

What's the specific relationship/formula between work frequency and output current/input output voltage/inductance value?

  • 0
    TI__Mastermind 27470 points

    HI Huanghai:

    see below description:

    At even lighter current loads, PFM is activated to maintain high efficiency operation. When either the minimum HS switch ON time (tON_MIN ) or the minimum peak inductor current IPEAK_MIN (300 mA typ) is reached, the switching frequency decreases to maintain regulation. In PFM, switching frequency is decreased by the control loop when load current reduces to maintain output voltage regulation. Switching loss is further reduced in PFM operation due to less frequent switching actions. The external clock synchronizing will not be valid when LMR23610 enters into PFM mode.

    so as the inductor average current is output current, the peak of inductor current is 300mA, with Vin, and VO, you will have Ton(inductor current raising time) and Toff((inductor current falling time) ) . 0.5*Ipeak*(Ton+Toff)/Tperiode=Io

    frequency=Io/(0.5*Ipeak*(Ton+Toff))

    Thanks