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CD40109B: Damage issue

Part Number: CD40109B

Hi expert,

My customer use CD40109B to convert 5V to 12V, however they find 3pcs out of 30pcs are damaged during pilot production. Below are customer's schematic and damaged IC's photo.  

Customer has tested the diode of each pin to GND by using multimeter‘s diode function, and the test results:

Damage Unit1:7,11,12,13,16 pin to GND is open, other pin to GND is 0.6 volts;

Damage Unit2: 11, 12, 13 pin to GND is open, 9, 10, 14, 15 pin to GND is 1.2 ~1.8 volts, other pin to GND is 0.6 volts; 

Good Unit3:12 pin to GND is open, other pin to GND is 0.6 volts.

Do you have any clue about the damage based these information? If you need any other information, please let me know.

Thanks and regards,


  • It sounds like they have a ground shift between their output and whatever it's connected to (not shown on the schematic). If the ground shifts by more than 0.6V, then the diode will forward bias and the current through it will destroy it.