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AMC130M02: AMC130M02 configuration

Bruce McAlister
Prodigy 10 points
Part Number: AMC130M02
Other Parts Discussed in Thread: AMC131M03EVM

Tool/software:

I am using an AMC130M02 for an isolated power bus voltage and current measurement, but have so far had no luck in establishing solid communication with the device to configure it. At one point we thought we had it configured and the DCDC was definitely running, but our board (custom based on datasheet example) will not enable the DCDC now and more interestingly, there appears to be no voltage at the DCDC_CAP output, which I did not think depended on configuration.

Should there always be a voltage (we measured ~2.6V) on the DCDC_CAP pin regardless of configuration state?

With the DRDY~ pin tied high with a 100kohm resistor (as was done in the datasheet example and on the AMC131M03EVM) how should we determine when the device is ready for communication after a POR or reset?

I did not notice in the datasheet any required long wait periods for communicating after POR or reset, but the AMC131M03EVM waits 1s between each communication after reset, taking 4s until the DRDY~ pulses start. Do we also have to wait ~1s after any kind of reset to establish communication with the AMC130M02?

  • 0
    TI__Expert 4010 points

    Hi Bruce,

    Bruce McAlister said:
    Should there always be a voltage (we measured ~2.6V) on the DCDC_CAP pin regardless of configuration state?

    There should be a voltage on the DCDC_CAP pin if DVDD is powered since the DCDC_CAP is connected to the output of the primary side LDO.

    Bruce McAlister said:
    With the DRDY~ pin tied high with a 100kohm resistor (as was done in the datasheet example and on the AMC131M03EVM) how should we determine when the device is ready for communication after a POR or reset?

    What mode are you using the DRDY pin in.  On startup the DRDY pin is push-pull, which doesn't require the 100kOhm pullup

    Bruce McAlister said:
    I did not notice in the datasheet any required long wait periods for communicating after POR or reset, but the AMC131M03EVM waits 1s between each communication after reset, taking 4s until the DRDY~ pulses start. Do we also have to wait ~1s after any kind of reset to establish communication with the AMC130M02?

    The wait time after a reset event should be tPOR , which is typically 250us.  After waiting that time you should be able to communicate with the device.

    Could you send a schematic and data captures of your communication attempts with the device?

    Thanks.

  • 0 in reply to Saleh Ahmad
    Prodigy 10 points

    Saleh,

    Thanks for the response!

    We did get the AMC130M02 configuration to take by putting 1s pauses between the reset command, the write commands, the read commands, the DCDC_EN set command, and starting the CLKIN clock. This takes over 5s to do with all the pauses, which isn't ideal.

    During POR I tracked the CDC_CAP pin voltage and found that it only measures the ~2.6V once the DCDC_EN bit is set. It came up within 10 microseconds of the DCDC enable command.

    We were originally using a 1ms pause after a reset because it was much longer than tPOR, but we couldn't get the configuration to work with that. I can't promise that that was the root cause, but the configuration certainly works with the 1s pauses. We can try the configuration again with only changes to the pauses and see what the result is.