LM46001: Light load efficiency appears higher at 500KHz than at 200KHz.

Hi, 

when LM46001 work at light load , the work mode will let it work at PFM model.  detailed description,  you can refer section 7.3.2.

so when work at PFM, the frequency will be different . and by different inductor and capacitor also have different loss in this condition which make the light load efficiency is different.

Do you have any concern in system application using this device when work at 1mA loading?

Thanks

Thank you for your answer Daniel,

The differences you describe for PFM mode are what I am asking you about in the test setup. The two efficiency charts only state operating frequency as changed variables.

Greater efficiency at 500KHz is contrary to typical trends.

I'm asking if there is an error in the charts or another variable that accounts for the anomaly.

My 200KHz application is 10% more efficient at 10Vin than 28Vin. I would like to support this trend with your datasheet.

Thank you for your help, and best regards,

Dave

Hi Dave：

I am not very clear about the datasheet efficiency curve setup, but I tested the EVM board with different inductor value, 500K with18uH 42Vin, 5V1A, the input current is 217.8uA ,  for 200k with 47uH, 5V 1mA is 204.5uA. 

For 10V and 28V, normally 10V will be higher due to low power loss at internal LDO and power loss on the fet. 

hope it helps.

Thanks