SNLS020D July 1999 – August 2016 DS90LV031A
PRODUCTION DATA.
- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
- 8 Detailed Description
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
9.1 Application Information
The DS90LV031A has a flow-through pinout that allows for easy PCB layout. The LVDS signals on one side of the device easily allows for matching electrical lengths of the differential pair trace lines between the driver and the receiver as well as allowing the trace lines to be close together to couple noise as common-mode. Noise isolation is achieved with the LVDS signals on one side of the device and the TTL signals on the other side.
See Related Documentation for general application guidelines and hints for LVDS drivers and receivers.
9.2 Typical Application
Figure 9. Point-to-Point Application
9.2.1 Design Requirements
When using LVDS devices, it is important to remember to specify controlled impedance PCB traces, cable assemblies, and connectors. All components of the transmission media must have a matched differential impedance of about 100 Ω. They must not introduce major impedance discontinuities.
Balanced cables (for example, twisted pair) are usually better than unbalanced cables (ribbon cable) for noise reduction and signal quality. Balanced cables tend to generate less EMI due to field canceling effects and also tend to pick up electromagnetic radiation as common-mode (not differential mode) noise which is rejected by the LVDS receiver.
9.2.2 Detailed Design Procedure
9.2.2.1 Probing LVDS Transmission Lines
Always use high impedance (>100 kΩ), low capacitance (<2 pF) scope probes with a wide bandwidth (1 GHz) scope. Improper probing gives deceiving results.
9.2.2.2 Cables and Connectors, General Comments
When choosing cable and connectors for LVDS it is important to remember:
Use controlled impedance media. The cables and connectors you use must have a matched differential impedance of about 100 Ω. They must not introduce major impedance discontinuities.
Balanced cables (for example, twisted pair) are usually better than unbalanced cables (such as ribbon cable or simple coax) for noise reduction and signal quality. Balanced cables tend to generate less EMI due to field canceling effects and also tend to pick up electromagnetic radiation as common-mode (not differential mode) noise which is rejected by the receiver. For cable distances < 0.5 m, most cables can be made to work effectively. For distances 0.5 m ≤ d ≤ 10 m, Category 3 (CAT 3) twisted pair cable works well, is readily available, and relatively inexpensive.
9.2.3 Application Curves
Figure 10. Typical DS90LV031A, DOUT (Single-Ended)vs RL, TA = 25°C
Figure 11. Typical DS90LV031A, DOUT
vs RL, VCC = 3.3 V, TA = 25°C