TFT LCD driver problem!

bigbat

TFT LCD driver problem! [Copy link]

Recently I want to understand the problem of LCD driver. I saw a LCD on the Internet. It is Innolux AT070TN90, 800X480, 16-bit color, LED backlight, digital driver chip RA8875 and LCD interface data of lpc1788. Now the question is: how to drive the backlight of the LCD? Can I just give voltage to the relevant pins of the LCD, or do I need any special measures? Is there any expert who can give me some guidance!

bigbat

I saw this circuit diagram on RAIO's website. I would like to ask the experts, what are the two signals VLED+ and VLED-?

SYLVA

VLED+ and VLED- are the backlight power supply terminals of AT070TN90, which are explained in the AT070TN90 manual!

bigbat

SYLVA posted on 2019-1-31 08:51 VLED+ and VLED- are the backlight power supply terminals of AT070TN90, which are explained in the AT070TN90 manual!

How much voltage and current do these two need to drive? What kind of signal is it, is it a PWM pulse?

箫林

LCD backlight is best driven by constant current. There are many similar backlight driver ICs.

箫林

It is recommended that you choose a professional LCD display company with backlight driver and TFT driver products. If you do it yourself, the parameters cannot be controlled well, the LCD will flicker, the effect will be poor, etc.

bigbat

The LCD I use is a 7-inch screen. According to the information, it uses an AIC1896 chip and is boosted by PWM. The 6-LED backlight requires about 20V voltage. 3.3X6=19.8V

bigbat

According to the information, the AIC1896 chip requires a 1.4Mhz external PWM pulse. Do you have any chips that do not require external PWM?

想跳水的朱

用MP3202也可以，其EN腳用PWM控制或直接接高都可以，另外RA8875是比較老的產品了，用RA8889會再爽

harchy

bigbat posted on 2019-1-31 09:16 How much voltage and current do these two need to drive? What kind of signal is it, is it a PWM pulse?

LCD LED backlight reference circuit:

If you still don't understand, you can add QQ 598076690 for discussion.