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UCC14240-Q1: maximum capacitive load?

Stefan Lintner
Expert 5185 points
Part Number: UCC14240-Q1

Tool/software:

Hi,

in the DS section 8.2.2.1 the calculation of Cout2 and Cout3 are the capacitor between (COM−VEE) and (VDD−COM) respectively.

If the module is used at single output configuration such as (VDD – VEE) 18 V to 25 V, then how much is the maximum capacitive load the module can handle during power up with the maximum resistive load ?

BR,
Stefan

  • 0
    TI__Mastermind 33115 points

    Stefan,

    The only issue with large output capacitance is the possibility of longer soft start time. The soft start timer starts once VIN crosses UVLO and stops when PG is LOW FB has reach 90% of set value. With UCC14240, we allow 16mS for this to happen. This time has been extended to 34.8ms for all other variants.

    Max resistive load is determined from the maximum power vs temperature derating curves shown in the data sheet and also found in the Excel Design Tool. Please be sure to use the Excel Design Tool to help properly configure the UCC14240...also recommend to use UCC14241 instead of UCC14240.

    Regards,

    Steve

  • 0 in reply to Steven Mappus1
    TI__Expert 6650 points

    hi Steve, 

    Please could you let us know if you have the rough estimate of the maximum capacitive load for the soft start timer until 16 ms.?

    Regards

    Andreas

  • 0 in reply to Isee
    TI__Mastermind 33115 points

    You can view the startup waveforms in section 5.4 of the EVM User Guide. Otherwise I suggest to order an EVM and configure it to the customer specifications and then test it.

    Regards,

    Steve