TPS78101 Vset=Vin

Shmuel Branover

In a circuit I designed I was not getting an output voltage and I found that Vset = Vin. I did a continuity check to check for a short and the pins are not shorted.

Are there any conditions that can cause this to happen?

over 9 years ago

0 Ryan Eslinger over 9 years ago

TI__Guru 55940 points

Hi Shmuel,

Could you provide a little more information to help us debug? Could you provide a schematic (a partial schematic around the LDO is fine)?

Very Respectfully,
Ryan

0 Shmuel Branover over 9 years ago in reply to Ryan Eslinger

Prodigy 40 points

Hi Ryan,

Thanks for your help. Bellow is the schematic:

The LDO will be used to power a MCU from a LI-Po battery but currently it is being supplied with 3.9 V from a PSU.

Pins In, EN and Vset all read 3.9 V, the output voltage reads 0.55V.

0 Ryan Eslinger over 9 years ago in reply to Shmuel Branover

TI__Guru 55940 points

Hi Shmuel,

On the schematic you sent it looks like you have OUT as pin 4 and Vset as pin 5. These are flipped from the actual device per the datasheet Pin Configurations. Could you confirm if your layout matches the schematic or the datasheet for the pin numbers?

Very Respectfully,

Ryan

0 Shmuel Branover over 9 years ago in reply to Ryan Eslinger

Prodigy 40 points

That'll do it, good find. I'm not sure how that happened as we used the same device in an alternate design.

Thanks for you help.

Power management

Power management forum

TPS78101 Vset=Vin