LVDS (Low-Voltage Differential Signaling) is a data transmission technology based on differential signals, offering high-speed communication with low power consumption and excellent immunity to electromagnetic noise (EMI).
It is widely used in applications such as:
- Display interfaces (LCD, TFT, OLED)
- Industrial and medical equipment
- Automotive systems
- Test and measurement equipment
- Data transmission between integrated circuits
⚙️ How does LVDS work?
LVDS transmits signals through two wires (differential pair) that carry opposite signals (+ and -). Instead of changing the voltage of a single wire relative to GND (as in single-ended signaling), LVDS transmits very small potential differences (~350 mV) between the two conductors.
Advantages:
- High transfer rate (up to several Gbps)
- Low power consumption per signal transition
- EMI noise immunity due to differential nature
- Low interference emission (ideal for sensitive environments)
📐 Technical characteristics
| Parameter | Typical value |
|---|---|
| Differential voltage | ~350 mV |
| Consumption per driver | < 10 mW |
| Data rate | Up to 3 Gbps or more |
| Signal type | Differential, low voltage |
| Characteristic impedance | 100 Ω (differential pair) |
| Topology | Point-to-point (or multipoint with care) |
🔌 Main types of connectors for LVDS
The LVDS standard defines the differential signal but does not impose a specific connector type. The choice depends on the equipment, application, and amount of data to be transmitted.
Common examples:
| Connector Type | Typical application | Characteristics |
|---|---|---|
| JAE FI-R / FI-X | Industrial LCDs, notebooks | Compact, 20–60 pins, fine pitch (0.5mm) |
| DF14 / DF13 (Hirose) | Industrial boards, backplanes | 10–40 pins, low profile |
| Micro-Coaxial (I-PEX, JAE) | Cameras, high-resolution displays | Up to 30 channels, excellent signal integrity |
| FFC/FPC | Consumer displays, automotive | Flat, low cost, used in panels |
| DVI (internal LVDS mode) | Legacy monitors | 24 channels or more, encapsulated |
| Customized (IDC, pin header) | Internal industrial projects | May vary as needed |
📐 Pin count
- Varies from 4 to more than 60 pins, depending on the number of LVDS channels and auxiliary signals (clock, enable, power, GND, etc.).
- One LVDS channel = 2 pins (positive and negative)
- Example: for 4 data channels + 1 clock → 10 pins just for differential signals, excluding auxiliaries.
🛠️ Testing implications
In the validation of DUTs with LVDS, it is important to consider:
- Compatibility with the physical connector (fit, locking)
- Correct pinout and polarity
- Line impedance (typically 100 Ω differential)
- Instrumentation with specific probes or dedicated adapters
🔧 LVDS interface testing
In industrial environments or laboratories, it is common to test LVDS signals to ensure:
- Signal integrity (jitter, overshoot, noise)
- Correct connectivity (pinout and impedance)
- High-speed communication with DUTs
AJOLLY Testing designs test benches with support for LVDS interfaces, including:
- Instrumentation compatible with high frequency (oscilloscopes, logic analyzers)
- Fixtures with controlled impedance
- Waveform analysis and protocol decoding
- Functional testing in a production environment with traceability
🏭 Typical applications in the industry
- Testing of graphics cards, motherboards, and embedded systems
- Validation of camera modules and screens
- Medical and industrial imaging equipment
- Communication between FPGAs, ASICs, and high-speed sensors
LVDS is the right choice when you need speed, immunity, and energy efficiency. And it must be tested precisely to ensure reliability.