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CFAG240128LTMITZTS Manual Not Clear

Newbie99

New member
CFAG240128LTMITZTS Manual Not Clear :(

:confused:
I'm a new customer of Crystal Fontz. As my nick indicates I'm new with this graphic lcd but I'm not newbie in electronics.

I wrote this to complain you guys about my just first recently purchase 5 days ago, a CFAG240128LTMITZTS display.

During the wiring I checked the http://www.crystalfontz.com/products/240128l/datasheets/410/CFAG240128LTMITZTS.pdf to find out all the need voltages for the display but unfortunatly you have very confusing the indication of Vo.

Table 5 on page 5 just indicates "Supply Voltage for Lcd" for Vo:
Min = 16.3V, Typical=18.9V and Maximum=20.1V But you NEVER indicate its a NEGATIVE voltage!!!!



In table 4 of same page you again specify Min=0V, Max=21V but the minus sign is lost.

I tied the Vo pin to +5V hopping to work, result = black screen.
Then I re-check the manual and as it state typycal 18.9V I tied it to +12V. inmediate result = short circuited display, power supply fuse blown.

It was frustrating to never see the display working. At home I did a deep search of projects made by people using similar displays of CrystalFonts. I discover you have to use a 10K pot, sweep arm to Vo, one side to Gnd and the another to the -17V output of the Display itself.

Fortunatly I'm electronics repair so back at work I find the only thing shorted was a SMD capacitor. I replaced it and finally I got the LCD working.

Maybe I'm miss something at the manual but as I note there is a lack of indication of the minus sign on table 4 and 5 of page 5...

I don't blame you at all for the damage because finally I did the damage but seriously I encourage you to indicate clearly that for volatge Vo this is a negative voltage. I have seen on this formum other people asking the same doubts as me so it will good for you to put a application schematic at the end of the manual at least for illustrative purpouses.

I will finish my product design and I will need more displays from you as I'm going to manufacture a commercial product. Just want to share my feelings, it's embarrasing to burn a new item before it works.

Regards.
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You may notice in the data sheet that "Supply Voltage for LCD" is given as "Vdd-Vo", which means that it is referred to Vdd (+5 volts). So, for a Vdd-Vo of 18.9 volts, that means 18.9 volts below +5 volts, which is -13.9 volts as measured to ground.

Your contrast pot should be connected from Vdd (+5), not ground, on one end, and the -17 volt supply (Vee) on the other end. The wiper goes to the Vo pin, of course.
 
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