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Error rate of capacitor between EXT_CAP and Vss

Category: Datasheet/Specs
Product Number: AD5271

I'm using two AD5271 in pallarell, one for control brightness of LED and one for control sensitivity photo diode.
Datasheet discribes 1uF capacitor should be connected between EXT_CAP and Vss and the voltage rating of capacitor should be ≧7V.

My question is error rate of capacitance.
In my board, both AD5271 has 1uF capacitor between EXT_CAP and Vss, and most of boards works fine, but some boards fell into uncontrolable state of RDAC value, and the capacitor of these boards are corrupted in short-mode.

So I want to know the error rate of capacitance.
If you have any suggestions or information, let me know.

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  • Hi Azki,

    We do not have data regarding the error rate of the capacitance. I have few questions regarding your setup. what is your Vdd and Vss? What is your capacitor voltage rating? You can increase the voltage rating of your capacitor as having a lower voltage rating can affect the capacitance of the capacitor. How does the board fail? What do you do before it fails?

    Best Regards,

    Yokki

  • Hi Yokki,

    Thank you so much for your support.

    Vdd: 5V
    Vss: 0V
    Voltage rating: 16V

    So I thing the voltage rating is enough for AD5271...

    I'm using two AD5271 in parrarell, one for control brightess of LED, and the rest for control sensitivity of photo diode.
    Unfortunatelly, there is no signes before is fails, the AD5271 for PD is suddenly fell into uncontrolable state.
    The sequence of my software is below:
    1. Send Commnand 1(0x4xx) to update RDAC value.
    2. Send Commnand 2(0x800) to read RDAC value.
    3. Send Commnand 0(0x000) to read data from DIN(must be RDAC value).
    In the case of failure, data from DIN at step 3 is 0x3FFF (because of 2 bits right-shift).

    B.R.

    Azki

Reply
  • Hi Yokki,

    Thank you so much for your support.

    Vdd: 5V
    Vss: 0V
    Voltage rating: 16V

    So I thing the voltage rating is enough for AD5271...

    I'm using two AD5271 in parrarell, one for control brightess of LED, and the rest for control sensitivity of photo diode.
    Unfortunatelly, there is no signes before is fails, the AD5271 for PD is suddenly fell into uncontrolable state.
    The sequence of my software is below:
    1. Send Commnand 1(0x4xx) to update RDAC value.
    2. Send Commnand 2(0x800) to read RDAC value.
    3. Send Commnand 0(0x000) to read data from DIN(must be RDAC value).
    In the case of failure, data from DIN at step 3 is 0x3FFF (because of 2 bits right-shift).

    B.R.

    Azki

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