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LMG1025-Q1EVM: Dead on arrival

Holly Maness
Prodigy 10 points
Part Number: LMG1025-Q1EVM

Our company ordered the LMG1025-Q1EVM for evaluation.  We followed the start-up procedure described in the manual, observing all standard ESD protocols and carefully checking all voltages applied to the board.  

We tried out the first recommended test to make sure that the pulse was present at the FET gate and found no signal.  Working back, it was evident that there was no output from the pulse shortener.

Tracing the trigger pulse forward through the input pulse shortener through the first gate (SN74LVC1G08DCKR) revealed that the signal is present at the input, but there is no signal at the output of this gate.  Clearly this gate is dead and the board is DOA.

When we called TI customer support for a replacement, we received a completely unhelpful email response (see below).

How do we get a replacement board?

********************

"How are you? I hope you are doing well upon receipt of this email.

A pleasant day to you and thank you for reaching out to us here at Texas Instruments.

After further evaluation of your inquiry, I believe that a discussion with one of our product/applications engineers would be a great help for your inquiry. With this, I would like to advise you to post your inquiry to our engineer-to-engineer (E2ETm) forum. E2E is where we have the Engineering Applications Specialist according to the product line. The forum is supported by our experts, and you will be interacting with them. 

You can post your inquiry using this link: e2e.ti.com/.../addpost 

Have a great day ahead.

Kind Regards,

Jonard Rico
Texas Instruments Customer Support"

  • 0
    TI__Expert 6325 points

    Hi Holly,

    I'm sorry to hear about your troubles with the EVM. As all of our EVMs have a test procedure that needs to be passed during manufacturing to ensure customers receive a working board, I'm curious to know if there could be issues that arose after it was shipped. If no signal is present at the output of the pulse shortener, could you check to see if any components on the board from the schematic snip below have soldering issues, loose, or broken off?

    Thanks,
    Rubas

  • 0 in reply to Rubas Khalid
    Prodigy 10 points

    Visual inspection does not show any cold solder joints or any obvious flaws.  It is getting Vcc on pin 5 and GND on pin 3. The input pulse is present at pins 1 & 2 (post RC filter).

  • 0 in reply to Holly Maness
    TI__Expert 6325 points

    Hi Holly,

    Thanks for the inspection. Can you measure the bias current of the AND gate? If those results are not what we expect, I can help in the replacement process.

    Thanks,
    Rubas

  • 0 in reply to Rubas Khalid
    Prodigy 10 points

    As we previously explained, the signals at the input of the AND gate are correct.  VCC and GND are present at the chip, but there is no output signal driving the gate driver. I do not see how any other tests are relevant; we have a a defective product.  Please tell us how to get a replacement board.

  • 0 in reply to Holly Maness
    TI__Expert 6325 points

    Hi Holly,

    The current test is for reference purposes to compare the quiescent current of that broken chip with a working chip. Reach out to customer service again and explain that E2E has confirmed that the EVM is defective, and they will most likely process the replacement. We can also move this to email with our team to help you with the replacement process if you need more information after submitting the request. I sent you a friend request on E2E, where we can exchange info, so for now I will be closing this thread.

    Thanks,
    Rubas