LM5149-Q1EVM-400: Weird operation of the Evaluation Board.

Shivam Gupta

Prodigy 30 points

Part Number: LM5149-Q1EVM-400

Tool/software:

I tried to power up the board with the following conditions:

1. At no load condition.

a. Tied PFM pin to VDD so that board works in PFM mode at light load and VCCX to GND.

b. Input voltage is set to 48V with current limit = 0.1A

Observations:

1. Output voltage = 2V.

2. VCC = 5V.

3. EN voltage = 8.5V

4. PG = 0.175 mV.

Can anyone let me know why PG is getting pulled down. If anyone has faced similar issue, please let me know how to debug it?

over 1 year ago

0 David Baba over 1 year ago

TI__Mastermind 40120 points

Hello Shivam,

Can you increase your input current limit and retry. The EVM should work in PFM mode, did you make any modifications to the board before trying the above?

Thanks.

David.

0 Shivam Gupta over 1 year ago in reply to David Baba

Prodigy 30 points

Hi David,

I tried to increase the current limit but still, it is not working.

0 David Baba over 1 year ago in reply to Shivam Gupta

TI__Mastermind 40120 points

Thanks for trying Shivam,

Just to confirm, did you make any changes to the EVM? Are you testing this out of the box, or have you been evaluating and something changed with its performance. Is R10 installed? Does the device work when you untie PFM and VCCX?

if so, I am assuming the part has been damaged somehow.

can you get the device to come up? ie. does loading help?

Thanks.

David.

Power management

Power management forum

LM5149-Q1EVM-400: Weird operation of the Evaluation Board.