Question about pin 15 & 16 of a CFAH2004A-YMC-JP LCD (4X20)

H

Hivera

New member
Hi everyone I wanted to know if anybody could help me find out what exactly is the 15 and 16 pin. In the User manual 15 has a symbol of A and a Description of LED +. The 16 pin has a symbol of K and the Description is LED -. Can someone please explain to me what LED + and LED - mean. And can someone tell me how to use them. What are the recomended voltages for each pin.

By there way this is for a CFAH2004A-YMC-JP LCD (4X20).
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S

spock

New member
LED

Here's the deal: A and K come from the Greek words Anode and Kathode. Roughly translated, ascent and descent. These pins are connected to the backlight, which is a LED array. All LEDs have an anode and a cathode, being this:
A -----|>|----- K
meaning that, since a LED is actually a diode (hence the name), one end is an anode, and the other a cathode. In order for a LED to emit light, it has to have a forward voltage, meaning that the voltage on the anode must be greater than the voltage on the cathode.
The recommended voltages you will find in the datasheet, where you will get a typical value as well as minimum and maximum tolerances for both voltage and current.
Any clearer now?
 
H

Hivera

New member
Hey do you know If I need a LCD driver or is there one built into my LCD display. This is for the CFAH2004A-YMC-JP LCD (4X20)
 
S

spock

New member
Driver?

What do you mean by driver?
Anyway, if you mean a driver for Windows, no, you don't as Windows don't detect anything on the LPT port. But you need a program to drive your LCD, like CrystalControl (given for free by CF in this site) or LCDstudio (given for free at www.lcdstudio.com ), among others.
Now, if you mean a segment driver for the LCD (quite unlikely), the LCD has all the circuitry necessary on-board; a controller (HD44780 or compatible) and two driver ICs are on the board, driving the LCD and making your life easier.
Will there be anything else, sire?
 
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