In source side applications, the TDP158 takes an AC-coupled HDMI signal and provides signal conditioning and level shifting to support TMDS signaling. Figure 8-5 provides an example of a DDC snoop version. Notes in both schematics provide important system design considerations. To help reduce overall EMI in a system the VCC and VDD decoupling capacitors need to be as close to the pins as possible. The drawings shown one set but multiple sets may be needed for each pin.

Control pins should be tied to 1kΩ pullup to VCC, 1kΩ pulldown to GND, or left floating. Drawings show 0Ω resistors as this provides flexibility. In noisy systems a 0.1-µF capacitor to GND may reduce glitches on these pins and are not shown in the drawings. As Figure 8-5 shows, connect the DDC source and sink pins to GND as the SCL/SDA_SRC if an application requires the DDC source and sink pins to be completely bypassed. If this is done, then the TX termination must be controlled by the TERM pin or through I²C.

Figure 8-5 TDP158 Source Side Application with DDC Snoop