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AFE539A4: Question about the contents of section "8.2.2" datasheet p56

Part Number: AFE539A4


I would like to ask you 2 questions as below about the datasheet 56page, section "8.2.2".

Q1) Why is the gain "4x" of ADC0 input ?

Which register should I set about the gain?

Q2) About "Kp"

According to the "Table 8-2", Kp is set to "0x0FA0" (=4000).

Will you tell me the meaning of the number (4000)?

Is this meaning "x4000", that is to say, "72dB", correct?

Thank you for your support.

Best Regards,


  • Hi Takumi-san,

    1) You set the reference for ADC0 in the DAC-0-VOUT-CMP-CONFIG Register:

    The example is using the 4x internal reference option for the ADC reference.  The H-Z input mode sets the full-scale input to VREF/3, so the full-scale input (VFS) range of the example becomes VFS =  (1.21 V * 4x) / 3 = 1.613 V 

    2) The state machine uses the equation OUT = Kp*error + (1/Ki)*integral(error) where Kp is the proportional gain term. The default Kp programmed into the AFE is 0x0FA0 or 0d4000 which is 72dB. You would tune the Kp to match what is required for the response time of your system. A higher Kp means a faster response but can lead to system instability. 


    Katlynne Jones

  • Hi Katlynne-san,

    Thank you very much for your reply !

    I understood well.

    Best Regards,