LM43601: Output of -12V not generated with a load of 500mA

Ishan Panchal

Part Number: LM43601

Hi There,

We have made same circuit for -12V as per THIS POST in Ti E2E forums. While doing output voltage ripple measurements at a load of 500mA, we observed that output of -12V is not being generated and there is a current flow of nearly 140mA in the load. This scenario happens when we are connecting load and then powering ON the input supply of +12V.

In case, we power ON the input supply and then connect the 500mA load then everything works fine. Please let me know if there is any solution to overcome this issue other than increasing the input supply voltage.

Thanks..!!!

over 2 years ago

0 Elena Gao over 2 years ago

TI__Genius 13735 points

hi, Ishan,

does it means the power sequence will effect the ability of loading current ? how about other loading like 100ma or less.

Elena

0 Ishan Panchal over 2 years ago in reply to Elena Gao

Intellectual 640 points

Hi Elena,

Thank you for the quick response..!!!

I checked and observed that this issue happens at nearly 500mA and above.

With a load of 490mA, it works okay.

0 Elena Gao over 2 years ago in reply to Ishan Panchal

TI__Genius 13735 points

hi, Ishan,

looking from the SCH the inductor is 47uh , for 500mA negative output it may close to the current limit, could you please check the inductor waveform , or try to change a larger inductor if this can help .

Elena

0 Ishan Panchal over 2 years ago in reply to Elena Gao

Intellectual 640 points

Hi Elena,

Thanks for suggesting possible solutions. As of now we are okay with the 490mA but I will test with the increased Inductor value and update.

Thanks..!!!

+1 Elena Gao over 2 years ago in reply to Ishan Panchal

TI__Genius 13735 points

hi Ishan,

That's ok ,I will mark close this thread, if more question please rise up a new.

Elena

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LM43601: Output of -12V not generated with a load of 500mA