Hello, everyone. Welcome to this LVDS educational series with Texas Instruments. My name is [? Charlie ?] [? Tai. ?] We're kicking off my series of LVDS educational videos to provide a better insight into LVDS technology and address some of the common questions.

Today I'll introduce LVDS technology, cover LVDS operations, and clarify differences between LVDS and other interfaces. LVDS, low voltage differential signaling, is a technical standard first introduced in 1994 as TIA/EIA 644. Typically, LVDS devices are divided into four categories-- driver, receiver, transceiver, and buffer.

Transceiver and buffer can be seen as pairs of drivers and receivers connected in different topologies, which share similar characteristics as LVDS driver and the receiver. So in this video, we'll focus on the operation of LVDS driver and receiver only.

LVDS devices can reach gigabits per second range. They offer high noise immunity, minimal EMI, low jitter and skew. LVDS devices are low cost, low power, and have been used extensively in applications such as laptop computers, office imaging, industrial vision, and medical.

When you look more closely, LVDS devices perform exceptionally well in backplane or rack-to-rack reach extensions and internal board-to-board communications. LVDS supports data, clock, and control signals, which opens endless opportunities for applications. We'll dive deeper into these benefits in the following videos.

But first, let's look at how LVDS devices operate. The basics of LVDS operation can be explained using this diagram. Here you can see we have four key components-- the driver, the receiver, differential pair, and the 100 ohm termination resistor.

The driver side has an always-on current source that drives a nominal 3.5 milliamp current through a differential pair. On the receiver side, the differential pair is terminated with a 100 ohm resistor. Since the impedance of the receiver is very high, all of the current effectively flows through the 100 ohm resistor. Ohm's law tells us that this will create a nominal 350 millivolts potential across the differential pair.

Let's look at the whole LVDS operation. The driver side can be viewed as CMOS switch. When the input signal is high, the 3.5 milliamp current first flows through the blue wire from the driver's side to the receiver side, across the 100 ohm resistor, then returns to the driver's side through the green wire. This creates a positive 350 millivolts potential at the receiver side.

When the input signal is low, the 3.5 milliamp current will flow through the green wire and return from the blue wire, which in turn creates a negative 350 millivolts potential at the receiver side. This positive and negative 350 millivolts together are used by the receiver to differentiate high and low input at the driver's side. The receiver threshold is guaranteed to be 100 millivolts or less, and this sensitivity is being turned over a wide common mode from zero volts to 2.4 volts. This is the very basics of LVDS operation and what enables some of the great benefits of LVDS technology.

Now, when talking about LVDS, sometimes there is confusion on what this term is referring to. Many people, even myself included at the very beginning, think that LVDS is a display interface. Is it OpenLDI or is it FPD-Link? No, it is neither.

LVDS is only a physical layer. A physical layer, according to the open interconnection model, defines electrical and physical specification of the data connection, which may include voltages, line impedance, and the signal timings. In the case of LVDS, some of the critical characteristics include 247 millivolts to 457 millivolts output range, 100 ohm load, 0.05 volts to 2.35 common mode input range, and plus/minus 100 millivolts threshold.

One layer above the physical layer is called data link layer, which defines how data gets transported. When you think of OpenLDI or FPD-Link, they are actually the combination of these two layers. Based on the LVDS standard, they also define, for example, the encoding or decoding of the data stream.

Think of LVDS as nothing more than a physical medium that transports signal from one point to another point. It is as simple as a driver, a receiver, a pairable wire with 100 ohm termination. Different data streams can be applied to the LVDS devices, and different names may be given to the system.

But LVDS is always the same underlying technology. TI offers a wide range of LVDS drivers and receivers that are suitable for different applications. For full portfolio, please go visit ti.com/lvds. Thank you for watching this video.