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IWR1843: failure analysis: unable to download software: VOUT_PA is 0V

HanDong
Prodigy 220 points
Part Number: IWR1843
Other Parts Discussed in Thread: UNIFLASH,

Hi there,

I have a failure case need your help: when I try to use Uniflash to download the software, it stuck at at the very beginning step: set break signal... Then I start to check the power rail... I find the VOUT_PA is 0V... in my design, I use a external LDO to supply 1.0V to this VOUT_PA pin... So I thought there might be some short issue when soldering the chip... I disconnect VOUT_PA with LDO output... Then I find external LDO output is back to 1.0V... VOUT_PA is back to around 0.2V.... and I re-try to download code with uniflash... this time, it works: the software could be downloaded successful... afterwards, I reconnect VOUT_PA with this LDO output... and run the software, the VOUT_PA is 1.0V.

Here are some questions:

1. from SPEC,  it mentioned: VOUT_PA: When internal PA LDO is used this pin provides the output voltage of the LDO. When the internal PA LDO is bypassed and disabled 1V supply should be fed on this pin... in my software, I bypassed internal PA LDO, so from HW design, a external LDO is used to supply this 1V to VOUT_PA.... Is this HW connection/deisgn ok? any conflict could occur when entering flashing mode? (I suppose IWR1843 will use internal LDO when entering flashing mode, then will we have a conflict between internal LDO and external LDO?)

2. when I disconnect VOUT_PA with external LDO, what voltage should I expect to measure on this VOUT_PA pin (reflecting internal LDO voltage)?   

3. how to understand the above behavior (VOUT_PA is 0 when download code, afterwards it is back to 1.0V when executing the software)?

Thanks and Best Regards

Dong 

  • +1
    TI__Mastermind 30025 points

    Hello, 

    Sorry for the delay. Your understanding on #1 is correct, this mode should not have any impact on flashing. The internal VOUT_PA LDO will not be turned on when the device is not configured. You will need to configure the sensor and start framing, then you should be able to measure 1.0V on the VOUT_PA pin if you are using the internal LDO.

    The expected voltage on the pin is 1.0V from the internal LDO.

    Regarding #3, this is expected behavior. The VOUT_PA LDO is disabled when the radar is not framing in order to save power, so you will not see any voltage on this pin. Only when you configure the sensor and start framing should you see 1.0V on this pin.

    Regards,

    Adrian

  • 0 in reply to aozer
    Prodigy 220 points

    Thanks. Adrian... Sorry for the late response. No idea why my email notification is not working... So I thought no reply yet...

    Best Regards

    Dong