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LMR36015: Design current vs real current.

Part Number: LMR36015

Hi, I use the TI webench to design a converter with followings parameters:

Vin: 5 to 55 V 

Vout: 4.55 V

Iout: 1 A

Considering desing and components used converter could supply 1 A. But testing the board with the converter, as maximum converter can supply 0.8 A. This current is in all the voltage range. The inputs can supply enough current to obtain 1 A as maximum. That is with a voltage from 6V to 55 V. 

But with 5V is different, with a power supply of 5V@1A I have an output of 0.5 A as maximum and with a 5V@3A I have an output of 0.7 A as maximum. 

First I think that the inductor is limiting to that current, but I chose it because its parameters and also in the webench don't show a problem if I use the inductor chosen. Part number is 7447713220.

Could you help to identify if the problem is the inductor or where the problem could be?

  • Hello Asael,

    The device has a peak current limit.

    Inductor ripple, which two variables being Vin and inductor selection will dictate the ripple. Half the ripple plus the DC load current is the peak inductor current.

    As Vin increases, ripple increases, so max DC load current would be less for higher input voltage.