LM76003: Inquiry about Vout difference between estimated and real measured

Michael Jeong1

Expert 2600 points

Part Number: LM76003

Hello Expert,

Our customer have an issue that Vout is out of spec.

If you see below table, their measured value was over of maximum spec.

We have debugged like below. But result is same.

-. Changed L1, C34.

L1 : 6.8uH. C34 : 47pF

L1 : 6.8uH. C34 : 4.7pF

L1 : 6.8uH. C34 : Open

L1 : 8.2uH. C34 : Open

L1 : 8.2uH. C34 : 4.7pF

If you know the root cause or debugging point, pls let me know the solution.

Here is measured value and schematic.

* Measured value

* Schematic

Best Regards,

Michael

over 3 years ago

0 Daniel Li14 over 3 years ago

TI__Mastermind 27030 points

when it our of your spec, is the condition is in light load or no load condition compare to full load condition?

FB accuracy indicated the internal reference erro. When the device working at PFM mode, the FB will be higher than 1%-2% then reference so that the device can work at PFM mode. refer Fig 41 and Fig43 in datasheet.

the regulation can be improved by pull mode high to make it work at FPWM mode.

Thanks

0 Michael Jeong1 over 3 years ago in reply to Daniel Li14

Expert 2600 points

Hi Daniel,

Thanks for your kind support.

I got it.

Regards

Power management

Power management forum

LM76003: Inquiry about Vout difference between estimated and real measured