LCD LED TV Tcon Voltages Data

VGH, VGL, VCOM, and AVDD voltage for TFT LCD

Most of the large TFT LCD panels out there require several bias and logic voltage levels to drive them, such as VGH, VGL, VCOM, AVDD, DVDD, etc. If the TFT display already has a driver board attached, it will most likely already have the means to product all these signals. But if you are using a display that only has a flat flex cable and needs you to supply these different voltage levels, you have no choice but to generate them in your circuit and provide the voltage levels.

What is tricky is keeping the cost of the design low. It is not at all efficient to use multiple boost converters to generate all these voltage levels. Also, making discrete transistor based boost converters can cause noise, flicker and sub-optimal performance of the display.

 

In this article, we provide a schematic to generate common VGH, VGL, VCOM, and AVDD rails from a single input voltage.

Common VGH, VGL, VCOM and AVDD voltage levels

TFT LCD panels always have a controller in there which is a CoG (chip on glass) type IC planted on to the panel to drive the rows and columns. The chip has referenace values and tables to drive the display to get the desired contrast and bias voltage needed to control the LCD pixels properly. Incorrect values can cause the panel to look low contrast and weak, or in the other extreme case cause permanent damage to the panel.

The CoG controller IC datasheet usually specifies a range of VGH, VGL, VCOM and AVDD values as absolute maximum rating. As a designer you must ensure that those values are not exceeded. Because the current draw is very little on VGH, VGL and VCOM, overshoots can be a problem in poorly designed circuits.

In addition to this, the LCD manufacturer configures the CoG LCD controller to use certain bias voltages that match the LCD panel characteristics (all LCD panels are not exactly the same). Here is an example from a 7″ display datasheet (ER-TFT07-2) with RGB interface.

Example of VGH, VGL, VCOM, and AVDD specifications for 7" TFT LCD panel

In most cases, the VGH level is going to be less than twice the AVDD level. VGL magnitude will usually be less than AVDD as well, but it will be negative.
To generate all these power rails, one can simply use a single boost converter to generate AVDD and use the switching function to operate charge pumps that generate the other voltage rails. VGH and VGL rails do not draw a lot of current and are easy to regulate using “discrete” linear regulator circuits as we will describe in the next section.

Samsung T-Con Voltages and Testing Guide Full Video 

https://fixledtv.com/

Samsung Tcon Voltages Data

Cof Data for

OB3372KP
SONY KDL42W670A
NT61804-C6520A1A
8697-BC562
RM76A30FA-906
ILD50711
RM76370FA-80A
8656H-C502
NT39538H-C1272B
SSD3272
--------------------------------
8658-B CBHI Cof Data
LN362038 Cof Data
8658-B CBHU Cof Data
RM76153FM-OCN Cof Data
RM76180FC-086 Cof Data
8656-F CY0B Cof Data
NT39530H-C5208A Cof Data
RM76112FD-032 Cof Data
RM76153FL-0C1 Cof Data
RM76190FA-0AO Cof Data
T7C75A1 LE4CCDN Cof Data
NT39538H-C1272A Cof Data
LS0306M1-C2LX Cof Data
RM7611WFD0-006 Cof Data
NT39329H-C0264A Cof Data

Nt39538H-C1288A
NT39563H-C6502A Cof Data
NT39504H-C02E8C Cof Data
NT39329H-C02A5A Cof Data
SSD3273U2R4 Cof Data
NT39530H-C5203A Cof Data
RM7611WFD0-006C Cof Data
8651-A CBD7 Cof Data
LH169K01 Cof Data
HM1OC005K-C1 Cof Data
8656M CY61 Cof Data
DB7931-FT01M Cof Data
T7C75A1 LE4CCDN Cof Data
S6CG242-51U Cof Data
8656-B CBJV Cof Data
56CG23A-52 Cof Data
8658-H C258 Cof Data
NT39530H-C5208A cof Data
NT39538H-1272A-B Cof Data
NT39538H-C12E4A Cof Data
NT61237H Cof Data
RM76152FJOA8 Cof Data
VHIL S0327B6-2L cof data
-------------------------------------------------
Raydium RM7611WFD0-006 Cof Data
Novatek NT39530H-C5203A Cof data
Sharp LH169K01 Cof Data
Novatek NT39329H-C02A5A Cof Data
Rayidum RM76153FL-0C1 Cof Data
T7C75A1 LE4CCDN Cof Data
Novatek NT39504H-C02E8C T400HW04 V.2 Cof Data
Rayidum RM76180FC-086 Cof Data
Novatek NT39538H-C1272A Cof Data
HM1OC005K-C1 Cof Data
8658-B CBJV Cof Data

ILI5271M2AA1

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