View previous topic :: View next topic |
Author |
Message |
Markdem
Joined: 24 Jun 2005 Posts: 206
|
Quick LCD question |
Posted: Fri Dec 03, 2010 6:15 pm |
|
|
Hello,
I have purchased the following LCD,
http://www.futurlec.com/LED/BLUE240X64LCD.shtml
I am a little confused with the power supply requirements. The first part of the specs says that the LCD Driving Voltage is 12v, but then on the pin connection part, it says that it is -10. I know I need to use a pot to control the contrast, but should it be a positive or negative supply??
Thanks
Mark |
|
![](templates/subSilver/images/spacer.gif) |
vinniewryan
Joined: 29 Jul 2009 Posts: 154 Location: at work
|
|
Posted: Fri Dec 03, 2010 7:42 pm |
|
|
Judging by the 'Absolute Maximum Ratings' your LCD's supply voltage range is -0.3V to +25.0V, and the typical application supply voltage is +12V, the -10V is a mystery no doubt but there are two other sources which suggest that you'll be safe supplying it with 12V. _________________ Vinnie Ryan |
|
![](templates/subSilver/images/spacer.gif) |
PCM programmer
Joined: 06 Sep 2003 Posts: 21708
|
|
![](templates/subSilver/images/spacer.gif) |
Markdem
Joined: 24 Jun 2005 Posts: 206
|
|
Posted: Fri Dec 03, 2010 10:32 pm |
|
|
Hi Vinniewryan,
This is what I thought, but I just want to make sure before I blow up a $70 LCD.
Hi PCM,
I have no problem getting the -10 supply, I am just not too sure if thats what it needs. I have sent a email to the supplier, but knowing them I will not get a very good reply.
Anyone else want to add their .02 ??
Thanks
Mark |
|
![](templates/subSilver/images/spacer.gif) |
PCM programmer
Joined: 06 Sep 2003 Posts: 21708
|
|
![](templates/subSilver/images/spacer.gif) |
Markdem
Joined: 24 Jun 2005 Posts: 206
|
|
Posted: Sun Dec 05, 2010 4:19 am |
|
|
Thanks PCM,
It has been confirmed that the LCD indeed does need a -10 rail. I will just use a charge pump from a faulty LCD i have sitting around.
I just wish this website had some proper data sheets.
Thanks
Mark |
|
![](templates/subSilver/images/spacer.gif) |
bkamen
Joined: 07 Jan 2004 Posts: 1611 Location: Central Illinois, USA
|
|
Posted: Sun Dec 05, 2010 11:32 am |
|
|
Most of the time, you really don't need the -10V... A lot of LCD's are visible at room temp at 0V contrast. BUUUTTTTtt...
If you are using a MAX232 somewhere for serial ports in your circuit, you can borrow some of the -10 it generates off the V- pin.
(fun)
Otherwise, building at least a -5supply is easy with something like a MAX829 style inverter or an ICL7660 (if I'm remembering the part numbers right).
You don't need a lot of current, As PCM mentioned, it's just a bias thing for LCD contrast.
-Ben _________________ Dazed and confused? I don't think so. Just "plain lost" will do. :D |
|
![](templates/subSilver/images/spacer.gif) |
|