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FDC2214-Q1: When INTB will be asserted after exiting sleep mode?

Cezar Morun1
Intellectual 315 points
Part Number: FDC2214-Q1
Other Parts Discussed in Thread: FDC2214

I am planning to use FDC2214 as follows:

1) FDC configuration:

  • RCOUNT set for 2ms conversion time
  • One channel active
  • INTB enabled
  • FDC2214 in sleep mode

2) Every 8 ms the processor will:

  1. the processor will wake-up the FDC2214
  2. the processor will go in sleep mode (waiting for an FDC2214 interrupt)
  3. In the related IRQ service routine, the processor will read the data from FDC2214 and put FDC2214 back in sleep mode

Questions:

  • When FDC2214 will assert the INTB after waking up?
  • After 2ms (set by RCOUNT) + 16,384 FINT (as per 7.4.3 in its datasheet)?

Thanks,

Cezar

  • 0
    TI__Mastermind 18545 points

    Hello Cezar, 

    Your understanding of the timing is correct. Assuming INTB is only reporting for the conversion completion (DRDY_2INT), then the timing for INTB would be the 16384*fint for the activation period, plus the conversion time for the sensor (the 2ms you mention being set by RCOUNT). 

    In the image, INTB would assert at the start of the first amplitude correction section. 

    Best Regards, 

    Justin Beigel

  • 0
    Intellectual 315 points

    Hi Justin,

    Thanks for the answer.

    I have two follow up questions:

    - I am using an external 12 MHz osc. I supposed sensor activation time (16,384 fINT) is based on the external clock, not the internal 40 MHz clock. Am I right?

    - what is the FDC power consumption during the sensor activation time (16,384 fINT)

    Thanks,

    Cezar

  • +1 in reply to Cezar Morun1
    TI__Mastermind 18545 points

    Hello Cezar, 

    Yes, since you are using an external oscillator, 12MHz will be used for this calculation. 

    During ramp up, the device supply current without coil excitation will be normal. The excitation voltage/current will be changing as it ramps up and we don't have a way to calculate that specifically but it will be less than the typical characteristics shown in the datasheet for that portion of the waveform. 

    Best Regards, 

    Justin Beigel