10.2.2 Detailed Design Procedure
The SNx5DP159 is a signal conditioner that provides AC coupling to DC coupling level shifting, to support Dual Mode DisplayPort-capable GPUs or GPUs with AC-coupled drive capability to support HDMI or DVI connectors and compliance. Signal conditioning is accomplished using receive equalization, retiming, and output driver configurability. The transmitter drives 2 to 3 inches of board trace and connector.
Designing in the SNx5DP159 requires the following:
- Determine the loss profile between the GPU and the HDMI/DVI connector.
- Based upon the loss profile and signal swing, determine the optimal location for the SNx5DP159, to pass electrical compliance.
- Use the typical application drawings in Use Case of SNx5DP159 for information on using the AC coupling capacitors and control pin resistors.
- The DP159 has a receiver adaptive equalizer by default but can also be configured for fixed value equalization using the EQ_SEL control pin.
- Set the VOD, pre-emphasis, termination, and edge rate levels to support compliance by using the appropriate Vsadj resistor value and by setting the PRE_SEL, SLEW_CTL, and TX_TERM_CTL control pins.
- Adding pre-emphasis will improve performance on bandwidth limited channels and make steeper transitions. VOD can be increased to compensate for DC losses and have a sheerer slope. SLEW_CTL handle transition inclination. Making the transition sharper will improve skew performance.
- The thermal pad must be connected to ground.
- See the schematics in Application Information on recommended decouple capacitors from VCC pins to ground.