ATL432LI: ATL432LI in fan control application issue

Rock Shao

Part Number: ATL432LI
Other Parts Discussed in Thread: TL431, ATL431LI

Hi,

My customer used ATL432LI in the fan control of the PC power, you can see the schematic as below;

U701 is an ATL432LI. The user finds that the fan continues to rotate slowly under light load. Normally, it should be stopped.

Is the Ika let the fan rotate? Could you help to check the schematic value? Thank you very much.

over 2 years ago

0 Marcoo Z over 2 years ago

TI__Mastermind 19550 points

Hi Rock,

can you share more information? What is the status of the +12VA? What is "light load" where is "light load" located?

0 Rock Shao over 2 years ago in reply to Marcoo Z

Expert 2905 points

Hi Marcoo,

The +12VA is PC power output voltage and the issue happened at the PC power output no load.

The customer used TL431 before and the Ika=100mA, the ATL432LI Ika is much smaller.

Is it possible that the leakage current of IKA caused the fan to rotate under no load? Is will increase R703 help? Will it cause other effects?

+1 Marcoo Z over 2 years ago in reply to Rock Shao

TI__Mastermind 19550 points

Hi Rock,

That is one good theory. From my observation, i agree with you. With no 12V there must be some leakage or something going.

In which case, the R703 is very small for this application. I do not think the ATL431LI needs 9.5mA to operate properly. Can you try changing to 10x the size and report any changes?

+1 Masoud Beheshti61 over 2 years ago in reply to Marcoo Z

TI__Genius 15971 points

We are closing this thread as we did not hear back from you. Thank you.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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ATL432LI: ATL432LI in fan control application issue