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AMC0306M05-Q1: AMC0306M05-Q1 get maximum and minimum wrong current only power on Auxiliary Power

Tianmei Luo
Prodigy 50 points

Part Number: AMC0306M05-Q1

Below is our SCH for HV input side current measurement.

Below is power supply when only Auxiliary power is on. 3V3_LV(DVDD) at low voltage side powers on firstly. After 132ms, 5V0_HV(AVDD) at high voltage side powers on later.

We draw the HV input current. We see a maximum negative current(-64A) jump to maximum positive current(64A) within ~5ms. It doesn't make sense. We only power on auxiliary power,  no HV input current now. Therefore, the senser output is wrong. Could you pls specify what's happening here?The senser power isn't stablished during this 5ms? Do I need to capture senser power supply and data signal(DOUT) together?

 

  • 0
    TI__Guru 59842 points

    Hi Tianmei, 

    When during the power-supply sequencing do you apply the external clock to the device? 

    What settings do you use in the SDFM?

    If you can also capture CLK and DOUT with the power supply sequencing, this can be helpful. The device should only require ~100us for proper operation. 

  • 0
    Prodigy 50 points

    Hi Alexander,

    Thanks for your prompt response. See waveform below: SDCLK is ok firstly duo to 3V3_LV built firstly.

    Then after 12.8ms, SDDAT is ok. Because at this time, 5V0_HV is established. Within this 12.8ms,

    there is no data in AMC0306. Now I can't see at which moment, we see min/max wrong current value(+/-64A).

    Any suggestions? Thanks.

    ...

  • 0 in reply to Tianmei Luo
    Prodigy 50 points

    Sorry, this is tested waveform. For each channel, see label for tested signal.

    The blue one is CLOCK signal, the green is DATA signal, the red is 5V0_HV.

    3V3_LV is already stable in the tested waveform. Thanks.

  • 0 in reply to Tianmei Luo
    TI__Guru 59842 points

    Hi Tianmei, 

    Looks like the device is initializing OK. 

    I would look for the timeout trigger function in your oscilloscope, then trigger on a data timeout. Either low or high since you have one of each in your output waveform. You can test the trigger by toggling your supply voltage and make sure you catch it OK. 

    Once we can start to reliably catch this behavior, then we can start to see if something is happening to the power supply or clock input which could help explain this issue. 

    Do you know anything else in your application turning on or off around these time stamps? Does it happen every time you initialize the system?