Vo Voltage etc

[Nikolai]

Hi!

Not suprisingly I have some problems with my lcd.

I'm just wondering what the voltages should be on j15 on the core, espessialy Vo. while talking about that can anyone tell me what Vcc, Vss, Vo, etc realy stands for?(i get that Vss is ground and Vd is 5v) Also my lcd spec talks about Vlcd, witch should be alittle lower than the logic's 5v.

, so to sum, what level should Vo have, and what does the letters stand for?

Best

Nikolai

[smashtv]

This terminology comes from long ago, numerous cave paintings indicate the origin as a European standards group.

V obviously stands for voltage,

D = drain,

S = source,

C = collector,

E = emitter

The double letter is/was used to note supply voltage, so where Vs and Vd are to denote these connections or values on an individual part, Vss and Vdd indicate the supply voltage.

All of this is a throwback to the caveman days of electronics, and in modern practice Vss is ground, Vdd is the positive rail.

The Vo thing -I think- is actually everyone trying to say V0 (that's V zero not "O"), and for most circuits this is the ground rail of the power supply.  This makes things easier to comprehend on circuits with multiple voltages and negative rails.  This explanation of V0 is pure speculation on my part, if anyone knows the whole story please share.......

Hopefully this history as I have heard it is correct, all this is from way before my time.  ;D

Best!

Smash

[moebius]

Thanks for the history lesson ;)

----

As in the world of its better known sibling LSD - nothing should be taken for granted, when it comes to LCDs ;D

Deciphering LCD supply naming is a tedious job..

Core V_s at least is, V_ss

Core V_d is V_dd or maybe V_cc

But here's where the diversity really begins - "contrast" or "LCD drive" voltage:

Core V₀ can be, well V₀, V5, V_{"some number"} or maybe V_ee

BUT - V_ee can also be separate negative power supply for extended temperature range LCDs..

Go figure :D

And how to figure right voltage for that "LCD drive" or "Contrast"? Adjust it so you can see ;)

BUT - If you happen to have extended temperature range display, it might need negative LCD drive.. It doesn't break with positive voltages, but you simply don't see anything.

MB core just can't supply negative voltages, so you'll have to figure out, how to generate one.. (7660 charge pump? ;))

Bye, Moebius