philpem.me.uk Samsung LT133X1-106 LCD panel  

Samsung LT133X1-106 LCD panel

The Samsung LT133X1-106 is a fairly small (13.3 inch), XGA (1024x768), full-colour (6-bit RGB) TFT-LCD panel with a CCFL backlight and an LVDS interface. They were used in a number of laptop computers, most notably the Dell Latitude CP and CPi series -- this means they're quite commonly found on the surplus market (usually as "used-but-good" spares from laptop spares dealers), and as a result they're cheap.

I'm working on connecting one of these panels to an Enterpoint Drigmorn2 development board -- this page will document my progress.

Inverter -- Dell DAINVMPB201 Rev 3B

This is one of the really neat aspects of the LT133X1. The inverter is a single module which can usually be found wrapped in a tin shield and either glued or bolted onto the back of the LCD panel. It has some really nice features:

  • Standard power supply voltages (5V and 12V)
  • Built from standard parts for which data is available (TI/Unitrode UC3872 Resonant Lamp Ballast Driver, Dallas DS1803 Digital Potentiometer).
  • Lamp brightness controlled over an I2C/SMBus serial link ("W1" output)
  • Second 'variable voltage' output ("W0", output range is unknown but expected to be from 0V to 5V and has 8-bit resolution)

The pinout isn't documented anywhere that I can see, so I reverse engineered it by tracing pins with a multimeter. I started by figuring out where the ground pins were (they're usually the easiest to find), then working backwards to find Vcc, SDA, SCL and so on. Finally, a bit of track-following revealed the function of the last pin (the W0 output from the Dallas digi-pot).

The pinout is as follows:

Pin Function
1 UC3872 Vc (+12V)
2 UC3872 Vc (+12V)
3 UC3872 Enable (5V = lamp on, 0V = lamp off)
4 DS1803 Vcc (5V, keep active)
5 I2C Serial Data (SDA)
6 I2C Serial Clock (SCL)
7 DS1803 pin 12 (Wiper 0)
8 UC3872 Vcc (5V, can be switched off to save power)
9 Ground
10 Ground

When holding the board so the Dell logo is at the bottom right, pin 10 is at the top of the board, and pin 1 is at the bottom.