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IWR6843: What are the working conditions of this internal VOUT_14SYNTH LDO?

Hui Chen
Intellectual 430 points
Part Number: IWR6843

Hi TI experts.

Based on iwr6843isk-ods EVM, I have designed our own millimeter wave sensing products. The relevant parts of 6843 are completely consistent with EVM. A total of 20pcs have been produced, and one of them is not working properly. The phenomenon is described below.

1. The CFG serial port can be connected to the computer, but the data serial port shows no connection. So we can't received any valid data from DATA serial port.

2. Measuring the power supply on the board, it is found that the B13(VOUT_14SYNTH, Internal LDO output) pin has no 1.35v voltage output, but the normal board has 1.35v output at this pin. The voltage of other points is consistent with the normal board. What are the working conditions of this internal LDO?

Our boards are inspected by 3D X-ray when they leave the factory, which can completely eliminate the soldering problems.

Can you provide some analysis and detection ideas for us to double check? We are afraid of similar problems in mass generation section.

Best regards

  • 0
    TI__Mastermind 33805 points

    Hi,

    1. Are both ports showing up on the device manager?
    2. Are there any difference in the process between the working and failing board?
    3. Can you confirm that the failing device is booting up in the right mode? you can check using an oscope that the SOP line is stable at 3V3 prior to reset crossing 1V5
    4. Besides the VOUT_14SYNTH are there any other voltages rail differences on these boards?

    Regards,

    Charles O

  • 0 in reply to Charles Oladimeji
    Intellectual 430 points
    1. Are both ports showing up on the device manager?
    • ----Yes, both of these two UART can be found on the device manager.
    1. Are there any difference in the process between the working and failing board?
    • -----No, there is no any difference. I have 20PCS boards, all of them am exactly the same, including process for test.
    1. Can you confirm that the failing device is booting up in the right mode? you can check using an oscope that the SOP line is stable at 3V3 prior to reset crossing 1V5
    • -----Yes, I double check it , the SOP line status is correct. I also can capture the data tansaction waveforms at UART and SPI interface. 
    1. Besides the VOUT_14SYNTH are there any other voltages rail differences on these boards?
    • ----So far, I have not found any other difference.

    Regards

  • 0 in reply to Hui Chen
    TI__Mastermind 33805 points

    Hi,

    Can you share your schematics?

    Did you connect MSS logger on the device to your USB to UART? 

    Regards,

    Charles O