The Difference Between LVDS And TTL Interfaces on TFT Displays

Views: 238     Author: Reshine Display     Publish Time: 2023-12-18      Origin: Site

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The Difference Between LVDS And TTL Interfaces on TFT Displays

TFT displays are now found in a wide range of products, including televisions, laptop computers, appliances, handheld instruments, and other devices. The incorporation of thin film transistors into LCD architecture increased the use of LCDs across all market segments significantly. Each transistor in the thin-film transistor (TFT) technology used in liquid crystal displays (LCD) serves as a pixel (that is, each of the tiny elements that control the illumination of your display). Because each pixel contains a transistor, the current needed to turn on and off the pixel lighting can be reduced. On TFT displays, there are two types of interfaces: LVDS and TTL.


1. TTL interfaces are found on TFT displays

When the display panel was first introduced, the traditional digital interface, TTL, became the industry standard. The required bandwidth was 300Mbit/s, the resolution was VGA in 6-bit color, and the panel size was less than 10 inches. TTL integrated circuits represent small-scale to large-scale integration, with each chip containing hundreds of transistors. In comparison to analog designs, TTL represented a low-cost integrated circuit that enabled the use of commercially viable digital techniques.


Low voltage differential signaling, or LVDS, is a transmission standard that uses differential signaling to transfer display data. These interfaces have advantages such as flexible panels, high-definition graphics, and rapid frame rates because fewer connections are required to interact with the display. Low system costs and dependability are typically associated with the LVDS standard. Because LVDS requires less power to operate, has a simple design, and is in high demand. LVDS uses a differential data transmission technique that is more resistant to common-mode noise than single-ended systems. The differential technique has the advantage of efficiently rejecting noise that is connected to the two wires as common-mode noise because it only considers the difference between the two signals (the noise appears on both lines equally). The noise is significantly reduced or eliminated.


2. What does the "0" or "1" on the LVDS interfaces mean?

When using LVDS, which uses two wires, the voltage difference between the two wires represents a "0" or a "1". TTL, on the other hand, uses a voltage about ground to denote a "1" or a "0," respectively. TTL operates at a specific voltage level depending on the power supply used. This has gradually been standardized at around five volts. This is significantly higher than the approximately 350mV used by LVDS. LVDS consumes significantly less power than TTL.


Another advantage is the inherent resistance to LVDS interference. The use of twisted pairs, which results in close electromagnetic field coupling, is one important reason. Regardless, the wires will be subjected to the same voltage spikes. As a result, the differential voltage remains constant. When using TTL, a voltage spike during "0" transmission could result in a "1" at the receiver.


3. Understanding Low Voltage Differential Signaling (LVDS)

LVDS is a low-voltage differential signaling-based method of transmitting display data. These interfaces have advantages such as versatile screens, high-definition visuals, fewer connections, and higher frame rates.


Signals can be transmitted in three ways: single-ended mode, common mode, and differential mode. In single-ended mode, the driver and receiver are linked by a line that transmits data. In the conventional method, data is transferred using a single-ended or pair of differential lines. When noise is connected to either the near-end or far-end signal source, interferences in the circuits can occur. A differential pair, also known as an LVDS, is a pair with opposing polarities that connects the driver and receiver to form the differential mode. Because LVDS employs differential signaling, information is transmitted as a voltage difference on a pair of wires, which is then compared at the receiver.


4. LVDS transmission rates

When it comes to data transmission rates, LVDS stands out and outperforms options like RS-422 and RS-485. It is, in fact, so fast that it typically operates at 655 Mbps but can also operate at speeds ranging from 1 to 3 Gbits/s. High speeds are critical in some use cases, particularly for mission-critical end products like medical devices, diagnostic tools, and consumer electronics, and LVDS is an excellent low-cost data delivery option. The standard is also widely regarded for its low power consumption, which allows battery-powered devices to run for longer periods.


LVDS is praised for its low power consumption in data transmission, making it the ideal interface for projects where energy is a primary concern. Displays are well known to be a major power drain, especially when users prioritize backlighting and high-resolution displays. With a power draw as low as 1.2 V, it's easy to see why this is such a popular interface. Lower supply voltages frequently result in lower power consumption because they lower the voltage across termination resistors and increase current flow.


The differential data transmission mechanism used in LVDS is more resistant to common-mode noise than single-ended systems. The differential technique has the advantage of effectively rejecting noise that is coupled onto the two wires as a common mode (the noise appears on both lines equally) because the receiver only considers the difference between the two signals. Noise is effectively reduced or eliminated.


The LVDS standard is commonly associated with low system costs and reliability. Because of the lower power consumption requirements, LVDS is less expensive both initially and over time. The design is relatively simple, and its versatility is in high demand, allowing associated hardware to become more affordable purely through economies of scale.


In summary, LVDS transmits information using voltage differences on a pair of wires, which allows for relative simplicity, lower hardware costs, and higher information transmission rates while reducing noise. On TFT displays, LVDS consumes less power, can support a greater transmission distance, and uses a serial mode of transmission that requires fewer wires. Visit Reshine Display to learn more about our display technology offerings if you want to use the LVDS standard on a TFT display in your next interface.

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