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UCC27624-Q1: internal diode between VDD and GND

Part Number: UCC27624-Q1
Other Parts Discussed in Thread: UCC27524, UCC27624

Hi Expert, 

My customer has some questions about VDD and GND pin. Customer use the diode gear of multimeter to measure the internal diode between VDD and GND. 

When the red probe on the VDD and black probe on the GND pin, the read voltage is 1.1V. When the red probe on the GND pin and black probe on the VDD pin, the read voltage is 0.5V. 

Customer measure two units of UCC27524, and not soldered on the board. The read voltage are the same. 

Could you please kindly confirm this phenomenon? Customer has some concerns that it may have some additional leakage flow from the VDD to GND. 

If this phenomenon is normal, could you please help me understand why there have 1.1V diode between VDD and GND pin?


Ethan Wen 

  • Hello Ethan,

    I tried to recreate this on my own UCC27624 IC and I got open for VDD-GND and about 0.6V for GND-VDD. When its on the board I get totally different results, presumably because of things like the VDD capacitor. So I'm not sure why we are getting different results, even on the UCC27524. 

    In any case, I would not trust the diode measurement from VDD to GND. There is no large diode like that in the device, but it may be that other structures are causing a false reading of one. The best way to see if there is some leakage problem is to measure that directly. I would suggest applying a VDD voltage with no switching/load and see if you get these results:

    (leaving the inputs/enable floating should put you in the OFF state when VDD is applied)

    By measuring the quiescent current directly, your customer can rule out any issues/concerns with the diode drop measurement. Feel free to reply with any follow-up or additional questions.


    Alex M.