• Resolved

ISO7821: Dead Short from pin 16 to pin 9

Part Number: ISO7821

Every one of the parts that I received has a short from pin 16(Vcc2) to pin 9(Gnd2).

Measuring with a Fluke 179 I have high resistance from pin 16(Vcc2) to 15(Gnd2) and high resistance from pin 15(Gnd2) to 9(Gnd2) but zero Ohms from pin 16(Vcc2) to pin 9(Gnd2).

These are cut-tape parts from Digikey ordered about 3-weeks ago.

  • Hi Dan,

    Thank you for using our E2E forum.

    Could you please clarify the full part number you received?

    We have two different pinouts in the 16SOIC footprint. One is a 16DW and another is a 16DWW. The pinout is not the same between the two options and perhaps a mix-up may have happened?

    Please refer to the comparison diagram below I put together based  on page 6 of the ISO7821 datasheet. The 16DW package may have been delivered and the impedance measurements you are seeing align with the diagram/pinout on the left:

    For 16DW:

    • Pin 16: GND2 <> Pin 15: NC : High-impedance  - this is normal
    • Pin 16: GND2 <> Pin 09: GND2 : Dead short      - this is normal
    • Pin 15: NC      <> Pin 09: GND2 : High-impedance  - this is normal

    The DWW package has the pinout where pin 16 = Vcc2, pin 15 = gnd2 = pin 9.

    I realize/acknowledge that this small difference can be confusing. Hope this helps!

    Best regards,


    PS:  Fixed Typo. Clarified post to say that Pin 15 (NC) impedance to pin 09 (GND2) : expected impedance is high.