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ADC128D818: Calculation of power consumption

Hailiang Zhang
Expert 4745 points
Part Number: ADC128D818

Hi Team,

Could you please help to understand how to calculate the power consumption of adc128d818? The engineer is calculating the power requirements of a power supply. Thanks.

Regards,
Hailiang

  • 0
    TI__Guru**** 168895 points

    Hi Hailiang,

    Can you please refer to section 9.2.2.1 in the datasheet and let us know where the confusion comes from?  The power consumption depends on # of channels used and if the temp sensor is being accessed along with the sample rate of the ADC128D818.

  • 0 in reply to Tom Hendrick
    TI__Expert 4745 points

    Hi Tom，

    I was looking at chapter 9.2.2.1. Does Equation 6 correspond to low power mode only. When considering the power requirements of the power supply, I think it is necessary to consider the peak value in the continuous conversion mode, including the power consumption of the I2C read and write circuits. From the datasheet, I didn't find relevant data. 

    Regards,
    Hailiang

  • 0 in reply to Hailiang Zhang
    TI__Guru**** 168895 points

    The datasheet does not include I2C loading, but it does have digital input loading (page 8).  Worst case power consumption is during continuous operation, so that would be appropriate way to validate the MAX power consumption.  You can always substitute the 4.93mA number in the equation with the current values shown on page 6.

  • 0 in reply to Tom Hendrick
    TI__Expert 4745 points

    Hi Tom，

    Could you please describe in detail how to calculate the maximum power consumption? Thanks!

  • 0 in reply to Hailiang Zhang
    TI__Guru**** 168895 points

    Hi Hailing,

    To understand the average supply current (I+), the conversion rates must be understood. ADC128D818 has three types of conversion rates: Continuous Conversion Mode, Low Power Conversion Mode, and One Shot Mode. You have not told me what conversion mode you wish to use.  In the Low Power Conversion Mode, the device converts all of the enabled channels then enters shutdown mode; this process takes approximately 728 ms to complete. (More information on the conversion rate will be discussed in the Conversion Rate Register — Address 07h and One-Shot Register — Address 09h sections). Each type of conversion produces a different average supply current. It also depends on if you are using the TEMP sensor.  If you care to describe in detail how you are using the ADC128D818, I'll try to give you details on how to calculate the power consumption.