TPS7A25: TPS7A2533DRVR – Getting Only 1.08V Output on Fixed 3.3V LDO

SAI KIRAN SATRAM

Part Number: TPS7A25

Tool/software:

Hi everyone,

I'm currently working on a board that uses the TPS7A2533DRVR LDO, which should output a fixed 3.3V. However, I'm only getting 1.08V at the output.

To troubleshoot, I have desoldered the following components which were part of the feedback network:

R894
R1776
R1777
C2188

Since this is a fixed-output version, I understand that the feedback resistors are not required and FB pin should be connected internally.

Despite removing these components, the issue persists—I'm still measuring around 1.08V at the output.

I'm attaching the relevant portion of the schematic/layout here for review. Could anyone please help verify if the surrounding circuitry is correct and if there are any issues I might have missed?

clues : Input 5V and enable 5v is coming,

Any suggestions would be greatly appreciated!

Thanks,
Sai Kiran

4 months ago

0 Aaron Paxton 4 months ago

TI__Expert 5605 points

Hello Sai,

I know you are not using the adjustable option but please be aware that the reference voltage is 1.224V. If you were to use the adjustable option with the resistor divider above, your output would be ~5V (nominal).

Have you looked at the output on a scope? I am guessing you are measuring 1.08V on a DMM? If so, it would be good to understand whether that's a constant dc voltage or the averaging of fluctuations.

~ Aaron

0 SAI KIRAN SATRAM 4 months ago in reply to Aaron Paxton

Prodigy 20 points

Hello Aaron,

yes, thanks for the study of that sch, so yeah what i have mentioned 1.086 volts this i am getting on DMM. i will check with once CRO , i will conform you in short along with output waveforms.

for clarity i am mentioning again, i have removed resistors,