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encoder

Chin-Win Lin
Prodigy 110 points
Other Parts Discussed in Thread: ADS7861

The ADS7861 wery easy to damaged How to protect?

I use ADS7861 to decode SIN/CON encoder (with PMSM motor driver 15KW power).
The ADS7861 work on mode #3
Before enable PWM Signal (IGBT control signal) The ADS7861 work normally
but after enable PWM Signal The ADS7861 damaged

  • 0
    TI__Guru**** 173936 points

    Hi Chin-Win Lin,

    Can you describe for us how you have the ADS7861 connected to your encoder?  Would it be possible for you to share a schematic?  I suspect when you enabled the 15KW power, there may have been a differential voltage developed across the AGND/DGND boundaries which exceeded the +/-300mv limits or perhaps caused spikes that were above/below the rails.  Any detail you can supply which may help us help you locate the potential cause of damage would be greatly appreciated.

  • 0 in reply to Tom Hendrick
    Prodigy 110 points

    Hi  Tom : Yes I think you are right. when turn on the PWM(Big power ) I measure
     The voltage of  AVCC/AGND ,The grounding bounce generate,  the Voltage up  to 1   ~~1.5 Volt 

    How to eliminate grouning bounce ?

    Regards

  • 0 in reply to Chin-Win Lin
    TI__Guru**** 173936 points

    Hi Chin-Win,

    Ground bounce can usually be attributed to layout and component selection.  Having local bulk capacitance can help relieve issues between the supplies and ground - the ADS7861 has two supply pins and two ground pins.  Pins 1 and 12 should tie directly to the same ground point (preferably a ground plane).  Pins 13 and 24 should also be tied to the same +5V rail.  If you can send along your schematic and/or layout, we'd be happy to review them for you.