The TMDS461 is a 4-port digital video interface (DVI) or high-definition multimedia interface (HDMI) switch that allows up to four DVI or HDMI ports to be switched to a single display terminal. Four TMDS channels, one hot-plug detector, and a digital display control (DDC) interface are supported on each port. Each TMDS channel supports signaling rates up to 3 Gbps to allow 1080p resolution in 16-bit color depth.

The TMDS461 provides an analog adaptive equalizer for different ranges of cable lengths. The equalizer automatically compensates for intersymbol interference [ISI] loss of an HDMI/DVI cable for up to 20 dB at 3 Gbps (see Figure 19).

When any input port is selected, the integrated terminations (50-Ω termination resistors pulled up to VCC) are switched on for the TMDS clock channel, the TMDS clock-detection circuit is enabled, and the DDC repeater is enabled. After a valid TMDS clock is detected, the integrated termination resistors for the data lines are enabled, and the output TMDS lines are enabled. When an input port is not selected, the integrated terminations are switched off, the TMDS receivers are disabled, and the DDC repeater is disabled. Clock-detection circuitry provides an automatic power-management feature, because if no valid TMDS clock is detected, the terminations on the input TMDS data lines are disconnected and the TMDS outputs are placed in a high-impedance state.Read more