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UCC28C42: Expected max quiescent current draw when COMP=0V

BrandonAzbell
Guru 63560 points
Part Number: UCC28C42

To disable the UCC28C42, the COMP pin can be grounded.

Under that condition, what is the expected maximum supply current?

  • 0
    TI__Mastermind 26095 points

    Brandon,

    Unfortunately since the max sourcing current is not a measured parameter, we can only adhere to the min and typical values given in the data sheet. I found your question asked at least two other times on E2E and you can refer to these cases: case 1, case 2, for additional insight. My advise is that the typical 1 mA should be followed as the max value for normal operation. For abnormal operation, such as pulling COMP pin LOW (GND) to command zero duty cycle, the maximum sourcing current is internally limited to protect the error amp. You could connect COMP to GND and measure the current limit to confirm how much margin above 1 mA exists? You could also recommend pulling CS HIGH>1.1V as a shutdown method?

    Regards,

    Steve M

  • 0 in reply to Steven Mappus1
    TI__Guru 63560 points

    Steve,

    Thank you for the references to the other threads.

    Just to clarify, the intention is to understand the total current consumption of the UCC28C42 when disabling it.

    This circuit will be in a product that needs to have a low standby current consumption, ie. <1mA.  What I am trying to ascertain is whether I can disable the UCC28C42 by manipulating the COMP pin and want to understand the resulting current from the input supply.

  • +1 in reply to BrandonAzbell
    TI__Mastermind 26095 points

    Brandon,

    Pulling COMP LOW will force COMP into current limit. Since the parameter is not measured, you would need to verify in circuit whether <1mA can be met from VDD. Other factors to consider: oscillator frequency, Rstart current, VREF loading, etc, which are all loading VDD in addition to COMP LOW. Low standby current is not a feature that was a thought when this family of PWMs were first designed.

    Regards,

    Steve M