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ADC S/H at the same time, without using simultaneous sampling

Mike Prechel
Prodigy 40 points

Hello all,

If the following configurations are made:

SOC0 - ADCINA0

SOC2 - ADCINB1


And SOC0 and SOC1 happen at the same time, which of the following events (if any) will happen?

1) ADCINA0 is sampled to S/H-A and ADCINB1 is sampled to S/H-B at the same time. Then, ADCINA0 is converted (because SOC0 has priority), then ADCINB1 is converted.

2) ADCINA0 is sampled to S/H-A and then converted.  Then ADCINB1 is sampled to S/H-B and then converted.

My problem is that in my system, SOC0 and SOC2 may or may not happen at the same time.  If they do happen at the same time, I need them both to sample as quickly as possible.  Unfortunately, I can not use the simultaneous sampling feature since the two will not always happen at the same time. 


Thanks in advance!

Edit:  I am using the Piccolo 28035.

  • 0
    TI__Guru 60865 points

    Hi Mike,

    The result is close to (2).  The SOCs will sample and convert sequentially, but which one goes first will be determined by the round-robin pointer and the priority configuration.

    If A0 and B1 are the highest priority channels, you should probably use SOC0 and SOC1 to convert them, and set the priority such that SOC0 and SOC1 are high priority.

  • 0 in reply to Devin Cottier
    Prodigy 40 points

    Hi Devin,

    Thanks for the quick response!


    That answers my question.  Unfortunately, unless they can sample and hold the two signals exactly when the SOC event occurs, there will be too much delay for our application.  It looks like we will have to skip some pulses to get the accuracy we need.


    Thanks again!

  • 0 in reply to Mike Prechel
    TI__Guru 60865 points

    Hi Mike,

    You could also look at F2837xD, F2837xS, or F2807x; these devices have multiple independent ADCs.