LCD Common Interface "LVDS, TTL, RSDS, TMDS" Technology principle Introduction

LCD Common Interface "LVDS,TTL,RSDS,TMDS" Technology Principle Introduction

1;lvds

Low-voltage differential signaling low voltage differential signal

A signal transmission model, proposed by the National Semiconductor Company in 1994, is a standard

It has a low power consumption while providing high data rates, and it has many other advantages:

1. Compatibility of low voltage power supply

2. Low noise

3. High noise suppression capability

4. Reliable signal transmission

5, can be integrated into the system-level IC

The product data rate using LVDS technology can range from hundreds of Mbps to 2Gbps.

It is a current-driven, by placing a load at the receiving end to get the voltage, when the current flow forward, the receiver output is 1, the reverse is 0

His swing is 250mv-450mv.

LVDS is a low-voltage differential signal transmission, is a new technology to meet today's high-performance data transmission applications. Because it allows the system to supply voltage as low as 2V, it can also meet the needs of future applications. This technique is based on the Ansi/tia/eia-644lvds interface standard. LVDS technology has a low voltage differential signal (250mvminand450mvmax) of 330mV and fast transition time. This allows the product to reach a high data rate from 100Mbps to over 1Gbps. In addition, this low-voltage swing reduces power dissipation while providing the advantages of differential transmission. LVDS technology is used for simple line drivers and receiver physical layer devices as well as more complex interface communication chipsets. The channel link chipset multiplexing and multiplexing slow TTL signal lines provide a narrow, high-speed, low-power LVDS interface. These chipsets can significantly reduce the cost of the system's cables and connectors, as well as the physical space required to cover the area of the connector. The LVDS solution offers designers new options for solving high-speed I/O interface issues. LVDS offers MW per gigabit solution for today's and tomorrow's high-bandwidth data transfer applications. The more advanced Bus LVDS (BLVDS) is developed on the basis of LVDS, and bus Lvds (BLVDS) is a new series of bus interface circuits based on LVDS technology, dedicated to the realization of multi-point cable or backplane applications. Unlike standard LVDS, it offers enhanced drive currents to handle the dual transmission required in multi-point applications. The BLVDS has a low voltage differential signal of approximately 250mV and a fast transition time. This allows the product to reach a high data transfer rate from 100Mbps to over 1Gbps. In addition, low voltage swing reduces power and noise to a minimum. The differential data transmission configuration provides the +/-1V common-mode range and hot-swappable devices of the active bus. There are two types of BLVDS products, which provide optimized interface devices for all bus configurations. The two series are: Line driver and receiver and serializer/Deserializer chipset. Bus LVDS can solve many challenges in high-speed bus design. The BLVDS does not require a special terminal to pull the rail. It does not require active terminal devices, the use of common rails (3.3V or 5V), the use of simple terminal configuration, to minimize the power consumption of the interface devices, resulting in very little noise, support business card hot Plug and the speed of 100Mbps to drive the heavy multi-point bus. The bus LVDS product provides a new choice for designers to solve the problem of high-speed multi-point bus interface.

2;ttl

TTL (logic gate Circuit) full name transistor-transistor logic, that is, BJT-BJT logic gate Circuit, is a commonly used in digital electronic technology, a logic gate circuit, the application of earlier, the technology has been relatively mature. The TTL mainly has the BJT (bipolar Junction transistor namely the bipolar junction transistor, the transistor) and the resistor Constitution, has the fast characteristic. The first TTL gate circuit is the 74 series, then appeared the 74H series, 74L series, 74ls,74as,74als and other series. However, due to the high TTL power consumption and other shortcomings, is gradually replaced by CMOS circuit.

TTL gate circuits are available in 74 (commercial) and 54 (military) two series, and each series has several sub-series.

TTL level signal:

TTL level signals are most utilized because the usual data representation is in binary terms, which is equivalent to logic "1", 0V is equivalent to logic "0", which is called TTL (transistor-transistor logic level) signaling system, which is the standard technology of communication between parts of the device controlled by computer processor.

TTL level signal for computer processor control of the internal data transmission is ideal, first computer processor control of the device internal data transmission for the power supply is not high and the heat loss is also low, in addition TTL level signal directly with the IC connection without the need for expensive line driver and receiver Circuit Furthermore, the data transmission inside the computer processor controlled device is carried out at high speed, and the operation of the TTL interface can satisfy this requirement. TTL communication In most cases, parallel data transmission is used, and parallel data transmission is not suitable for distances of more than 10 feet. This is because of both reliability and cost. Because of the problem of partial phase and asymmetry in parallel interface, these problems have influence on reliability.

TTL output high-level >2.4v, output low-level <0.4v. At room temperature, the general output high level is 3.5V, the output low is 0.2V. Minimum input high and Low: input high level >=2.0v, input low level <=0.8v, noise tolerance is 0.4V.

The TTL circuit is a current control device, the TTL circuit is fast, the transmission delay time is short (5-10ns), but the power consumption is large.

3;rsds

RSDS reduced swing differential signal low swing differential signal

This RSDS technology is suitable for thin-film crystal

Body-Tube (TFT) Liquid crystal display that supports larger images, higher resolution, and significantly reduces required components

Without increasing power consumption, bus interconnection, or overall cost.

Because of the growing picture of flat panel displays, simpler designs and lower power consumption are more important

notebook computers and other portable devices, the importance of these products must not be overlooked, because they have to be light-

The advantages of these two aspects cannot be sacrificed in order to improve clarity and reduce the number of components.

The use of RSDS technology can also add more important features and advantages to the new generation of display products. For example, you can

Significant savings in power consumption without compromising performance and resolution. For battery-powered and portable systems, this

Particularly important. The noise caused by electromagnetic interference can therefore be significantly reduced, resulting in lower production costs, while the product

We can also launch the market faster.

4;tmds--Minimizing transmission differential signal

In the late 90, Silicon image began to promote its ownership standards in the form of panel connections, digital Visual Interface (DVI) and high-definition multimedia Interface (HDMI) to the display industry-minimizing transmission differential signals (TMDS). In this case, the transmitter is blended with a higher-level encoding algorithm that reduces EMI characteristics on copper conductors, allowing the receiver to have robust clock recovery performance.
The 8-bit/10-bit encoding is a second-order process that converts a 8-bit input signal into a 10-bit encoding. Similar to LVDS, it uses differential signals to reduce EMI and increase the precise signal transfer rate. Also similar to LVDS, it is a serial transmission design.
DVI technology has been successfully applied in the field of PC, HDMI technology has also been successfully pushed to the consumer electronics market. However, TMDS has not become a widely used panel interface standard. Instead, LVDS, which has no royalties, has been widely used. In addition, the current version of DVI is not updated and has physical, functional and cost limitations.

difference between 5;LVDS low voltage differential signal and RSDS micro-amplitude differential signal

Although the two solution are different, but substantially the same, the purpose is to reduce EMI (electromagnetic interference), specifically, LVDS for the video card and LCD driver board between the T-con communication, Rsds for T-con and the source drive chip communication. At present, T-con has integrated the transmitting end of the LVDS receiver and the RSDS. Take the notebook computer, for example, the video card signal is first sent to the LVDS transmitter chip, after processing, the original 18-bit RGB signal, 3-bit control signal and a clock signal a total of 22-bit signal becomes 8-bit signal, and this 8 lines divided into 4 pairs, each pair of each other wrapped into T-con chip (why should they be entangled? The person who has studied physics should know that this will cancel out the magnetic field generated by each line, and note that the current in each pair of wires forms a loop. At the same time, the voltage amplitude is reduced to hundreds of cents.
To know the liquid crystal display and the communication between the host is huge, very high frequency, if not the use of LVDS and RSDS, the resulting EMI is enough to make the display is not good, if the laptop, but also interfere with other parts of the work.
After using LVDS and RSDS, the benefits are: 1. Reduce EMI. 2. Reduce the interface Connection 3 reduce the voltage 4. Operating frequency up to 455Mbps (XGA), 5 reduced PCB space
Note: LVDS and Rsds is actually two IC, if the T-con is not integrated, they are one to one to use, if integration, first make clear T-con model, then choose the appropriate LVDS transmitter chip and RSDS accept chip.
T-con is timing control, liquid crystal timing controller, is also the most important part of the LCD driver board.

General 20, 30 pin is LVDS, 30+45, 30+50 is ttl,40+40,35+35 is rsds,tmds more than the other motherboard a signal conversion chip

20pin single 6 definition:
3.3v 3.3v
1: Power supply 2: Power 3: Ground 4: Ground 5:r0-6:r0+ 7: Ground 8:r1-9:r1+ 10: Ground 11:r2-12:r2+ 13: Ground 14:clk-15:clk+ 16 empty 17 empty 18 empty 19 empty 20 empty
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (4 groups of the same resistance)
20pin Dual 6 Definition:
1: Power supply 2: Power 3: Ground 4: Ground 5:r0-6:r0+ 7:r1-8:r1+ 9:r2-10:r2+ 11:clk-12:clk+ 13:ro1-14:ro1+ 15:ro2-16:ro2+ 17:ro3-18:ro3+
19:clk1-20:clk1+
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (8 groups of the same resistance)
20pin single 8 definition:
1: Power supply 2: Power 3: Ground 4: Ground 5:r0-6:r0+ 7: Ground 8:r1-9:r1+ 10: Ground 11:r2-12:r2+ 13: Ground 14:clk-15:clk+ 16:r3-17:r3+
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (5 groups of the same resistance)
30pin single 6 definition:
1: Empty 2: Power supply 3: Power 4: Empty 5: Empty 6: Empty 7: Empty 8:r0-9:r0+ 10: Ground 11:r1-12:r1+ 13: Ground 14:r2-15:r2+ 16: Ground 17:clk-18:clk+ 19: Ground 20: Empty-21: Empty 22: Empty 23: Empty 24: Empty 25: Empty 26: Empty 27: Empty 28 empty 29 empty 30 empty
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (4 groups of the same resistance)
30pin single 8 definition:
1: Empty 2: Power supply 3: Power 4: Empty 5: Empty 6: Empty 7: Empty 8:r0-9:r0+ 10: Ground 11:r1-12:r1+ 13: Ground 14:r2-15:r2+ 16: Ground 17:clk-18:clk+ 19: Ground 20:r3-21:r3+ 22: Ground 23: Empty 24: Empty 25: Empty 26: Empty 27: Empty 28 empty 29 empty 30 empty
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (5 groups of the same resistance)
30pin Dual 6 Definition:
1: Power supply 2: Power 3: Ground 4: Ground 5:r0-6:r0+ 7: Ground 8:r1-9:r1+ 10: Ground 11:r2-12:r2+ 13: Ground 14:clk-15:clk+ 16: Ground 17:rs0-18:rs0+ 19: Ground 20:rs1- 21:rs1+ 22: Ground 23:rs2-24:rs2+ 25: Ground 26:clk2-27:clk2+
30pin Dual 8 Definition:
1: Power supply 2: Power supply 3: Power 4: Empty 5: Empty 6: Empty 7: Ground 8:r0-9:r0+ 10:r1-11:r1+ 12:r2-13:r2+ 14: Ground 15:clk-16:clk+ 17: Ground 18:r3-19:r3+ 20:rb0-2 1:rb0+ 22:rb1-23:rb1+ 24: Ground 25:rb2-26:rb2+ 27:clk2-
28:clk2+ 29:rb3-30:rb3+
The resistance between each group of signal lines is (digital table 100 euro) pointer table 20-100 Kohm (10 groups of the same resistance)
Generally 14pin, 20pin, 30pin for LVDS interface,
25, 31, 40, 41, 60, 70, 75, 80, 100pin interface for the TTL interface, where 41pin is the single 6-bit, 60pin above is a dual six-bit screen
50, the 50+30 pin interface is the RSDS interface. Single row white line.
The 14+20in interface is a TMDS interface, which is much less
One, all TFT-LCD Data Interface types:
Single TTL6 bit (8 bit), double TTL6 bit (8 bit), single LVDS6 bit (8 bit), double LVDS6 bit (8 bit), single TMDS6 bit (8 bit), double TMDS6 bit (8 bit), and latest standard RSDS
6-bit and 8-bit is used to indicate the screen can display the color of how much, 6-bit screen can display a color of 2 6 Times Square X2 6 Times Square X2 of the 6 square respectively represents the R G B three primary colors, calculate down the 6-bit screen can display a maximum of 262144 color, 8-bit screen is 16777216 colors. The screen display color is only related to the number of screen bits. Our laptop screen is generally 6-bit.
Early books are used 12 inches below the screen, the screen resolution is generally 640x480 (VGA) 800x600 (SVGA), using the interface for a single TTL6 bit, the screen on the PIN for 41-pin and 31-pin, 12-inch to 41-pin majority (800x600), 10 inches with 31 stitches (640x480). The TTL signal is the standard signal that the TFT-LCD can recognize, and the LVDS TMDS is encoded on the basis of it. TTL signal Line A total of 22 (the least, no land and power) divided by the R-G-B three-color signal, two HS VS field synchronization signal, a data enable signal de a clock signal CLK, wherein the r G G three primary colors in each base color and depending on the number of screen, and the number of different data lines (6-bit, and 8-bit) 6-bit screen and 8-bit screen three primary colors respectively have R0--R5 (R7) g0--g5 (G7) b0--b5 (B7) Three primary colors signal is a color signal, error will make the screen display color confusion. The other 4 signals (HS VS DE CLK) are control signals, which can cause the screen to not light and not display properly.
As the TTL signal level of about 3V, for high-speed long-distance transmission has a great impact, and anti-jamming ability is poor. So after the advent of the LVDS interface screen, as long as the screen is more than XGA resolution is used LVDS mode. LVDS is also divided into single-channel, dual-channel, 6-bit, 8-bit, the points, the principle and the TTL method is the same.
LVDS (low voltage differential signal) works by a dedicated IC, the input TTL letter encoded into LVDS signal, 6-bit is 4 differential, 8-bit is 5 groups of differential, the data line name is d0-d0+ d1-d1+ d2-d2+ ck-ck+ d3-d3+ If the 6-bit screen is not D3 -d3+ This set of signals, this encoding process is done on our computer motherboard. On the other side of the screen, there is also a decoding IC of the same function, the LVDS signal into a TTL signal, the screen is ultimately used as TTL signal, because the LVDS signal level of about 1V, and-line and + line interference can also offset each other. So the anti-jamming ability is very strong. It is very suitable for high-resolution screen which brings high rate of code.
Because high-split screen 1400x1050 (sxga+) 1600x1200 (UXGA) resolution is too high, the signal rate is correspondingly increased, single-way LVDS transmission has been overwhelmed, so all used is a dual LVDS interface, in order to reduce the speed of each LVDS. Ensure the stability of the signal.
For the XGA screen used in notebooks, usually 20-pin flat interface, the corresponding interface is defined as
1 vcc,2 VCC, 3 gnd,4 gnd,5 d0-, 6 d0+,7 gnd, 8 d1-, 9 d1+, GND, one d2-, d2+, GND, ck-,15, GND, 17 null, 18 Empty, 19 empty, 20 empty.

The high-split screen is a 30-pin flat interface, which is defined as:
1 GND, 2 VCC, 3 VCC, 4 empty, 5 empty, 6 empty, 7 empty, 8 da0-,9 da0+, ten gnd, one da1-, da1+, GND, da2-, da2+, GND, cka- , cka+, GND, db0-, db0+, and Gnd, db1-, db1+, GND, db2-, db2+, GND, ckb-, ckb+

LCD Common Interface "LVDS, TTL, RSDS, TMDS" Technology principle Introduction