LM5140-Q1: LM5140 VDDA pin

Nazli Deniz Çelik

Part Number: LM5140-Q1

Hi,

Vin=12V Vout1=3.3V Vout2=5V

Since our outputs are 3.3V and 5V, we connected the FB pins as follows. But when we take measurements, we can't see 5V on the VDDA pin, so the outputs are not as we expected. What could be the reason for this?

Best regards.

over 1 year ago

0 EricLee over 1 year ago

TI__Guru 53011 points

Hello Nazil

The device cannot start switching if no VDDA.

If the VDDA is less than 5V before start switching, the VIN pin voltage must be less than 5V.

-EL

0 Nazli Deniz Çelik over 1 year ago in reply to EricLee

Prodigy 130 points

Hi Eric,

When I check the VIN voltage, I read it as 12V, and all the EN and PG signals are also at the required value.

0 EricLee over 1 year ago in reply to Nazli Deniz Çelik

TI__Guru 53011 points

Hello Nazil

Then, please check the VDDA voltage again. The device cannot start switching if no VDDA.

-EL

0 EricLee over 1 year ago in reply to EricLee

TI__Guru 53011 points

Hello I am closing this thread since I have not heard from you for sometime.
Please feel free to open a new thread. Thanks
- EL

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LM5140-Q1: LM5140 VDDA pin