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CSD95490Q5MC: About REFIN pin of CSD95490Q5MC

Part Number: CSD95490Q5MC
Other Parts Discussed in Thread: CSD95372BQ5M
1.If you are not using TAO/FAULT, is it okay to connect the REFIN pin to GND? At this time, the TAO/FAULT pin will be open.
2.If the REFIN pin is connected to GND, what is the threshold voltage for OVERCURRENT DETECTION asserting the TAO/FAULT pin to 3.3 V?
3.When OVERCURRENT DETECTION works, does CSD95490Q5MC stop outputting itself?
  • Hello,

    Thank you for your interest in CSD95490Q5MC.

    1. The REFIN pin cannot be short to GND or floating. REFIN pin has to be biased with external reference voltage. Otherwise the power stage will consider at fault and will disable itself.

    2. If TAO is not used, it's better to bypass with 470pF cap, so that it wont be affected by noise. However, please do not short REFIN pin to GND.

    3. With properly configured REFIN pin, the overcurrent threshold is still same as specified in the datasheet.

    4. If overcurrent is detected in 10 consecutive PWM cycles, the TAO will be flagged high to 3.3V, but no action will be taken by power stage. The controller needs to make decision based on fault signal.

    Please let me know if you have more questions.

    Best,

    Qingquan

    user4263612 said:

    Part Number: CSD95490Q5MC

    1.If you are not using TAO/FAULT, is it okay to connect the REFIN pin to GND? At this time, the TAO/FAULT pin will be open.
    2.If the REFIN pin is connected to GND, what is the threshold voltage for OVERCURRENT DETECTION asserting the TAO/FAULT pin to 3.3 V?
    3.When OVERCURRENT DETECTION works, does CSD95490Q5MC stop outputting itself?

  • About answer No.1
    Does "disabling itself" mean to stop the power supply?
    Or is it to disable the overcurrent function?
    In our prototype, the REFIN pin of the CSD 95490 Q5MC is connected to GND, but it works without stopping the power supply.

    About answer No.2
    If I short REFIN pin to GND, will CSD95490Q5MC chip break?

    About answer No.4
    If the TAO signal is not controlled by an external logic, the power supply continue?

  • Hi,

    Please check my answer as below:

    1. You are correct, the CSD95490Q5MC only detects REFIN open. If you short REFIN to GND, the power stage is still operational, but you may not get correct current sense information. To make sure you have accurate current sense, we suggest to connect REFIN to external reference voltage with voltage level between 0.8V~2.5V.

    2. If REFIN short to GND, the power stage will not break.

    3. The problem here is, the current sense may not be accurate if REFIN is not properly configured. TAO signal is just a fault flag signal to notify the controller, If the controller doesn't take action to protect against the fault, the power stage supposes to continue operations. 

    Best,

    Qingquan

    user4263612 said:

    About answer No.1
    Does "disabling itself" mean to stop the power supply?
    Or is it to disable the overcurrent function?
    In our prototype, the REFIN pin of the CSD 95490 Q5MC is connected to GND, but it works without stopping the power supply.

    About answer No.2
    If I short REFIN pin to GND, will CSD95490Q5MC chip break?

    About answer No.4
    If the TAO signal is not controlled by an external logic, the power supply continue?

  • Please tell me about CSD95372BQ5M in the same series.

    1. When the REFIN pin is connected to GND,  the power stage cannot acquire correct current sense,
       but can it operate without stopping like the CSD95490Q5MC?

    2. If I short REFIN pin to GND, will CSD95490Q5MC chip break?

  • Hi,

    We do not suggest to operate with REFIN shorted to GND. but if you short the REFIN pin to GND, neither CSD95372BQ5M nor CSD95490Q5MC will break.

    Best,

    Qingquan

    user4263612 said:

    Please tell me about CSD95372BQ5M in the same series.

    1. When the REFIN pin is connected to GND,  the power stage cannot acquire correct current sense,
       but can it operate without stopping like the CSD95490Q5MC?

    2. If I short REFIN pin to GND, will CSD95490Q5MC chip break?