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UCD8220: Voltage on ILIM pin

Dominik Bejma
Prodigy 20 points
Part Number: UCD8220

Hello! I've set test jig (fig. bellow) for UCD8220 to figure out how current limiting works. The problem is: on ILIM pin I get 1V but datasheet for UCD8220 states that ILIM pin should be 0,5V when open. The only load on pin 8 is capacitor and 10:1 1M osciloscope probe. 

  • 0
    TI__Expert 6706 points

    Hi Dominic,

    ILIM is not open because there is a 100nF cap and +10V applied to VDD pin. 100nF has probably being charged by an internal supply current providing some DC voltage at ILIM pin.

    Thank you

  • 0 in reply to Manuel Alva Hernandez
    Prodigy 20 points

    Hi Manuel! 

    Thank you for your suggestion. I've removed the capacitor and nothing changed. Voltage at ILIM pin is still 1V while probing with a 1M oscilloscope probe, and also while probing with a 10M voltmeter. 

    However: while a resistor network is connected between ILIM, 3V3 and AGND pins, voltage at ILIM pin is as declared in the datasheet table. 

    At this point I assess that ILIM pin should always be connected to a resistor network due to it's unpredictable behavior. Maybe this issue needs second check and comment in the datasheet?