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TPS62400: TPS62400 Power Save Mode

Part Number: TPS62400
Other Parts Discussed in Thread: TPS62205

Hi Team,

I get a question about the TPS62400's Power save mode. 

Datasheets page 13 says during power save mode, output will be regulated to 1.01Vout_nom and it's monitored by a single threshold comparator.

From my understanding, the output needs to be regulated to 1.01Vout_nom, which means once the output rises up from Vout_nom to 1.01 Vout_nom, the controller will "hold" it at 1.01 Vout_nom using normal PWM operation. 

Suppose using a large inductor with very low ripple current, which means it can be CCM even in power save mode, then how the power save is effective? 

Even it can be DCM, it's the same case.

Some TI devices (such as TPS62205) uses pulse skip mode with dual threshold limit (like hysteresis comparator) and peak current limit, which means switch starts several cycles when at bottom limit and stops at top limit. I can under stand this control logic. 

So, could you help explain how TPS62400's Power Save Mode works with only single threshold comparator? 

thanks a lot.

Best regards,


  • Hello,

    as you said before increasing the inductance, the inductor ripple is decreased but the period remain the same, it  will change the transition point between PWM and PFM in terms of efficiency (going lower and on the left side of the plot). 

    In PFM (especially after a transition from PWM or voltage decrease after load transient) it is establish a kind of burst mode. This happen when a single burst is not enough to sustain the output. If you have further questions let me know, here it is my private mail: