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FDC2214: FDC2214

Part Number: FDC2214
Trying to get the lowest possible power consumption for FDC2214 I am looking for some answers:
  • How much power the internal 43.5MHz oscillator is taking?
  • Will the internal  43.5 MHz oscillator be shut down if the external clock is selected?
  • Can I read a measurement result while doing a conversion on the same channel? How many counters/registers are per channel?
  • Considering the following scenario:
  • do 4 channels continuous conversions (one for each channel : CH0 -> CH1 -> CH2 -> CH3 -> CH0 -> ...
  • can I read all 4 previous results (CH0 -> CH1 -> CH2 -> CH3 ->) while doing a conversion on CH0
  • Hello Cezar, 

    The internal oscillator does not shut down when the device uses an external oscillator and it is difficult to tell exactly how much power it is taking due to this. If you want to reduce power consumption, take a look at the Power Reduction Techniques for the LDC131x/161x for Inductive Sensing app note. Even though this is for an LDC device, there are still some relevant information here that can be used with the FDC2214. 

    You can read the data from a previous sample while the device is taking another sample. There are 2 register fields for each channel with the FDC2214. Combining these together gives you the data from the sensor. 

    When using multiple channels, they are sampled sequentially. Figure 13 in the datasheet is a good illustration for this. You can read the result of any channel while a conversion is happening but make sure to think about the timing of the data reads if you want to catch every data sample. 

    Hope this helps!

    Best Regards, 

  • Thanks Justin,

    Just to make sure I understood correctly: I can read the data from a previous sample while the device is taking another sample ON THE SAME CHANNEL.

    And another question: 

    Do you think it will be significant power consumption difference depending on the external clock frequency?

    e.g Setting the FDC2214 to do 125SPS on 4 channels (in total 500 SPS). Will changing  external clock  from 40MHz and 10 MHz ( of course after changing the RCOUNT_CHx registers to keep the same SPS) show some power savings?

    Thanks again,

    Cezar

  • Hello Cezar, 

    That is correct. The data will get overwritten at the end of the conversion period so you want to make sure you read before that time to make sure you did not miss the previous sample data. 

    It depends on  what you consider significant for this application. The external clock on the EVM adds a couple hundred μA to the power consumption when used. I would recommend doing some research on your potential external clocks to see if they provide power information. 

    Best Regards,