LM5069: LM5069EVAL

Jessica Blake

Part Number: LM5069

I am trying to validate the functionality of the LM5069 chip using the evaluation board. I tested the board as is first, and reached the correct cutoff of 2.5A. I need a current limit of 9A, so I switched R5 to 5mOhms, but this resulted in the board getting too hot with the power FET that was originally on the board. I switched the FET to be able to handle more current and power, however, the board is still getting very hot. Is there enough heat dissipation on the Eval board to accurately test at this amperage or is there a recommended method of heat dissipation for the chip and FETs

over 6 years ago

0 Rakesh over 6 years ago

TI__Guru** 105361 points

Hi Jessica,

Welcome to E2E!

What is the load (type and value) used for evaluation ? Can you share filled up design calculator http://www.ti.com/product/LM5069/toolssoftware

The following videos help you on how to use the Design Calculator. Please go through them and send me design tool for review. Thanks!

https://training.ti.com/node/1133677

https://training.ti.com/node/1133673

https://training.ti.com/node/1133664

https://training.ti.com/node/1133681

Best Regards,

Rakesh

0 Jessica Blake over 6 years ago in reply to Rakesh

Prodigy 60 points

3823.LM5069_Design_Calculator_REV_C.xlsx

0 Jessica Blake over 6 years ago in reply to Rakesh

Prodigy 60 points

I have been using the eval board and at first it seemed to work, and now it no longer switches off. I was wondering if it's possible the FET overheated and no longer works?

0 Rakesh over 6 years ago in reply to Jessica Blake

TI__Guru** 105361 points

Hi Jessica,

Change timer cap to 33nF and test again with PSMN4R8-100BSE FET.

On your second question: FET might have damaged. Have you checked ?

Best Regards,

Rakesh

0 Jessica Blake over 6 years ago in reply to Rakesh

Prodigy 60 points

I will look into those, right now I only have the evaluation board.

I have done a resistance check and it seems that there is still continuity in the FET.

Is the evaluation board set up to be able to handle 9A+ of current?

0 Rakesh over 6 years ago in reply to Jessica Blake

TI__Guru** 105361 points

Hi Jessica,

The EVM is designed for ~5A. I suggest to design custom board for your target specs and evaluate

Best Regards,

Rakesh

0 Jessica Blake over 6 years ago in reply to Rakesh

Prodigy 60 points

Thank you Rakesh.

In terms of creating the custom board, is it suggested to use the FET at a constant 8A current?

Thank you,

Jessica

0 Rakesh over 6 years ago in reply to Jessica Blake

TI__Guru** 105361 points

Correct Jessica.

A design with the external parameters to pass the target load current and overload cut-off.

Thanks,

Rakesh

0 Jessica Blake over 6 years ago in reply to Rakesh

Prodigy 60 points

Thank you Rakesh, I should be able to start verifying my design

Power management

Power management forum

LM5069: LM5069EVAL