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TPS543C20: TPS543C20 Device ILIM value

Balkis Mahammad
Prodigy 140 points
Part Number: TPS543C20

Tool/software:

Hi,

Am using the TPS543C20RVFT part in my device to convert 12V to 3.3V voltage, how can i calculate the ILIM resistor value.

Got the below formulae from datasheet, but am unable to get how this Rlim is choosen?

Vlim= ILim x RLIM 

Regards,

Balkis

  • 0
    TI__Expert 8476 points

    Hi Balkis,

    The OCP calculation is a few step process. First you calculate the desired VILIM using your desired OCP in equation (3), then you can use the ILIM with VILIM and ILIM (11.2uA) in equation (2).

    Best regards,
    Britton

  • 0 in reply to Britton Jones
    Prodigy 140 points

    Hi Britton,

    To verify these formulae, i have simulated the TPS543C20A device by keeping the below data and used the equation 2 and 3 to calculate RILIM value. 

    Data used to calculate:
    Freq = 1MHz
    OCP current = 42
    IND = 220nH
    VIN =12V
    VOUT = 3.3V
    RDS on = 0.58 mΩ |valid for VDD ≥ 5 V. Use 0.58 mΩ for RDS(on)
    VDD = 12V

    In calculation RILIM i got from eq 2 and 3 is 39.285K ~ 40.2K in simulation. Hence i assume approximate value is selected. Please correct me if am wrong.

    Attached simulation result.

    Thanks in advance.

    Regards,

    Balkis

  • 0 in reply to Balkis Mahammad
    TI__Expert 8476 points

    This seems correct. Thanks