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AM3351: Unused ADC channels

DJ-NG
Genius 9355 points

Part Number: AM3351

Hi champs,

customer doe snot need ADC and found in AM335 schematic checklist

  • Connect all TSC_ADC terminals (VREFP, VREFN, AIN[7:0], VDDA_ADC, and VSSA_ADC) to same ground as all VSS terminals.

He is unsure, if he really can connect all ADC inputs directly in parallel, so

can you pls confirm, that setting AN0..AN7, VREFP, VREFN all to VSS/GND is correct.

For my understanding this is correct usage.

  • 0
    TI__Guru**** 393215 points
    Hi,

    Please read Errata Advisory 1.0.32. Handling of Unused ADC channels is commented in the Workarounds section.
  • 0 in reply to Biser Gatchev-XID
    TI__Genius 9355 points

    After talking to customer, it seems, that advisory probably would not apply, because they hold ADC inactive and do not supply ADC.

    So VDDA_ADC can not rise before VDD_CORE. See from advisory:

    Any one or more of the TSC_ADC terminals (AIN[7:0], VDDA_ADC, VREFP,

    VSSA_ADC, and VREFN) may be temporarily connected together through internal paths

    during the power-up sequence. These internal connections can occur when the

    VDDA_ADC power source is applied while the VDD_CORE supply is not applied.

     

    Whats your opinion ?

  • 0 in reply to DJ-NG
    TI__Guru**** 393215 points
    If the ADC is not used at all, they can safely follow the Schematic Checklist recommendation:

    Connect all TSC_ADC terminals (VREFP, VREFN, AIN[7:0], VDDA_ADC, and VSSA_ADC) to same ground as all VSS terminals.