The TMDS442, 4-to-2 port DVI/HDMI switch, allows up to 4 digital video interface (DVI) or high-definition multimedia interface (HDMI) ports to be switched to two independent display blocks. The essential requirement of picture-in-picture display from two digital audiovisual sources is having two individual DVI or HDMI receivers in a digital display system. TMDS442 supports two DVI or HDMI receivers to enable multiple-source selection (picture-in-picture), as well as supports acting as a 4-input 1-output video switch.

Each input or output port contains one 5-V power indicator (5V_PWR), one hot plug detector (HPD), a pair of I2C interface signals (SCL/SDA), and four TMDS channels supporting data rates up to 2.25 Gbps. The 5-V power indicator and the hot plug detector are pulled down with internal resistors, forcing a low state on these pins until receiving a valid high signal. The I2C interface is constructed by an I2C repeater circuit to isolate the capacitance form both ends of the buses. TMDS receivers integrate 50-termination resistors pulled up to VCC, which eliminates the need for external terminations. An 8-dB input equalization cooperates to each TMDS receiver inputs to optimize system performance through 5-meter or longer DVI or HDMI compliant cables.

A precision resistor is connected externally from the VSADJ pin to ground, for setting the differential output voltage to be compliant with the TMDS standard for all TMDS driver outputs. The PRE pin controls the TMDS output to be operated under either a standard TMDS mode or an AC de-emphasis mode. When PRE = high, a 3-dB AC de-emphasis TMDS output swing is selected to pre-condition the output signals to overcome signal impairments that may exist between the output of the TMDS442 and the HDMI receiver placed at a remote location.Read more