This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS8320: Power consumption at 400Hz

Part Number: ADS8320

I'm interested in using this part to sample at 400Hz. Figure 23 in the datasheet shows the power consumption down to 1kHz. Does the curve continue to fall linearly (by 2.5x) if I sample at 400Hz, instead of 1kHz. Is there a static power consumption component?

  • Hello,

    In the ADS8320 datasheet, Figure 23 refers to error measurement test results, would you clarify which graph you are refering to that displays the power consumption.

    The power dissipation of the ADS8320 scales directly with the conversion rate, thus the lower the sampling rate the less power consumption the device will dissipate. But you are also correct that the device will hit a static power consumption as it does need a basic level of energy to operate.

    The cover sheet states that the device will dissipate 0.3mW at 10kHz with a Vcc of 2.7V, I predict this is when the device is in power down mode. In the electrical characteristic table, at Vcc=2.7V, it states that typical 1.8mW power dissipation at sampling rate of 100kHz is expected. Thus, that gives an idea of the minimum power consumption expected from the device.

    At sampling rate of 400Hz you should experience a lower linearly scaled power consumption than expected at a sampling rate of 1kHz, but I do not believe it will be a perfectly linear relation when hitting lower sampling rates.

    You can increase your power savings by taking advantage of the power down mode, as well as using the lowest Vcc supply your aplication can support. Other details on this can be found in section 10.3 of the datasheet.

    Regards, Cynthia

  • Cynthia,

     

    Indeed I made an error. It’s figure 36 that’s I meant. In the description it says that if you run the clock at a 2.4MHz rate but only convert at 1kHz it can go as low as ~7uA *  2.7V. My question is whether this curve scales further as we go down below 1kHz.

     

    Thanks,

     

    Renaldi

  • Renaldi,

    Yes the curve will continue to scale. I cannot guarantee it will scale linearly through the entirety of the lower frequency spectrum though, it will likely start flattening out at some point. I will check with design team in effort to get more specifics.

    Regards
    Cynthia
  • Renaldi,
    After checking with design team. Based on the datasheet information, figure 36 scaling should hold true untill supply current hits power down current. This means at 400Hz you can spec 3uA + scaled down active current.
    Power consumption is dictated by VCC and fCLK and sample rate.
    Regards
    Cynthia