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What is the correct voltage terminology for VDD and VSS?

I've been installing a Winstar WEH001602D OLED and was struggling until I realised that it appears to have pins 1 and 2 reversed compared to the usual convention. It requires +5 V DC on pin 1 and 0 V on pin2.

However in the abbreviated data sheet it says "pin 1, VDD, Ground Pin" and "pin 2, VSS, Voltage for logic" whilst the website says "pin 1, VDD, Supply Voltage for logic" and "pin 2, Vss, Ground Pin".

The WEH001602D's that I have definitely have the two pins reversed, though.

Alnitak
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  • only Pin 1 = 5V = Vdd is correct – Tony Stewart EE75 Jul 04 '18 at 21:50
  • Post a pinout diagram so we know what it looks like. – Transistor Jul 04 '18 at 21:52
  • @Transistor this is not so much about the pin out but about the terminology. I was fairly sure that VDD meant +ve (meaning that there are errors in their doc) but couldn't find a decent definitive confirmation of that. It is possible that those errors are why those pins have ended up reversed according to the usual convention for a display. – Alnitak Jul 04 '18 at 22:08
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    The "D" and "S" stand for the terminals of FETs: Drain and Source. In bipolar items, it's Vcc and Vee for Collector and Emitter. So the D or C are the positive and the S or E are the negative. If you've got Vdd, Vss and Vee, the Vee is negative of the Vss because, um... er, anybody? – Ian Bland Jul 04 '18 at 22:42
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    @IanBland Usually for bipolar circuits we have Vcc, **GND**, and Vee iff there is a negative supply. On CMOS circuits (except the ones that are functionally similar to TTL such as 74HC04 which follow the bipolar convention) we have Vdd, Vss and Vee, I guess as half-thought-out carry-over from the bipolar world. – Spehro Pefhany Jul 04 '18 at 23:08
  • Helpful but not a duplicate: [What's the difference between VCC, VDD, VEE, VSS](https://electronics.stackexchange.com/questions/17382/what-is-the-difference-between-v-cc-v-dd-v-ee-v-ss) –  Jul 04 '18 at 23:17
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    I reported the datasheet error to Winstar - they've now corrected it. – Alnitak Jul 05 '18 at 07:50

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