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CSD95480RWJ: LSET pin left floating?

Part Number: CSD95480RWJ

Hi,

My customer would like to confirm if the LSET pin of CSD95480, CSD95481 can be left floating?

Best regards,

Randy Chen

  • Hi Randy,

    LSET pin can not left floating. Please see use the datasheet graph to determine LSET resistor based on your inductor selection.

    Regards,

    Weidong

  • Hello,

    LSET pin can't be left floating on theCSD95480/95481. Customer needs to use the Data-sheet equation and determine the LSET resistor value based on Output Inductor they use. Should be resistor pull-down to GND configuration.

  • Hi Lucian,

    Can you specify more detail about the LSET function and the impact if it’s floating?

    Is it work abnormal with TI’s controller if floating, please advise? Thank you.

     

    Best regards,

    Randy Chen

  • Hi Randy,

    LSET is used to pin strap the inductor value during power on to center the current sensing circuitry in the appropriate range for the application.  If it is not set correctly, the current sensing circuitry will not behave correctly and will be inaccurate.  Since the current sensing signal in a typical application is used as part of the control loop, this signal is considered critical to the design.  Therefore, there is open-pin detection built into LSET that will flag the controller that there is an issue by holding TAO low if LSET is left floating.  Other than TAO being held low, the power stage will continue to respond to PWM inputs so it is up to the controller to protect the system.  You need to check the specific controller you are using to determine if it will correctly interpret the TAO low as an issue and prevent startup. 

    Best Regards,

    Evan Reutzel