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Original question:

ADS8411: Power Supply Sequence

ADS8411: ADS8411 Power Up issue, overheating

Dennis Meyer
Prodigy 10 points
Part Number: ADS8411
Other Parts Discussed in Thread: ADS9120

I am having a really weird  problem with ADS8411. I did project development with the device and had a working board. The analog and digital supplies were separate. At one point the device failed. I suspected it was because during power up I was exceeding the voltage difference between the to supply rails. I changed the design to where the two supplies are connected together. There now is only one +5V supply.

Since then I have replaced the part a number of times and have been unable to power it up. The device immediately overheats.

I noticed that one response listed this as a legacy device. Does this device have some kind of power up issue and is there a replacement?

  • 0
    TI__Mastermind 48150 points

    Hello,

    I am not aware of any power-up issues, but the device must stay within the ABS MAX specifications.  Specifically, +VA to +VBD must be in the range of -0.3V to +2.55V, but this can be violated for a few milliseconds during power-up; seconds would probably cause a device failure.

    During or before power-up, it is important that the digital inputs do not exceed +VBD by more than +/-0.3V, and the analog input does not exceed +VA by more than +0.1V/-0.4V.  

    Another common cause for ADC latchup is the use of separate analog and digital ground plane connections.  The ADS8411 should have all ground pins (AGND, BDGND) connected to the same analog ground plane.

    If you would like to switch to a newer device, the ADS9120 is the latest generation, 16b, 2.5MSPS device.  This device has fully differential inputs and a serial interface compatible with SPI.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    TI__Mastermind 48150 points

    Hello,

    Please let me know if you have any additional questions.

    Keith