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The inclusion of HDMI terminals in various locations on TVs and monitors has become more and more commonplace. This,along with the increasing size of screens, has in many cases made the distance between the image processor and the HDMI receiver farther, resulting in greater noise and EMI generation,necessitating buffer ICs, especially in large TVs (32″ to 40″ and above).

In many cases cables with lengths far exceeding 10m may be required for wall mounting thin-screen TVs or installing projectors on the ceiling. However, the longer the cable transmission length the greater the RF waveform decay, possibly resulting in incorrect transmission. In response to this ROHM integrates an equalizer that restores the deteriorated input waveform to its original state(Figure 1), enabling compatibility with 20m cables.

With HDMI transmission hot plug verification and code key exchange are performed approximately every two seconds.In addition, a content protection function called HDCP (High Bandwidth Digital Content Protection) is built in to prevent illegal copying. ROHM also integrates a DDC buffer that performs waveform shaping for stable HDCP operation and easy compliance(Figure 2).

HDMI requires high ESD resistance since it is an external interface and insertions and removals are relatively common. ROHM provides ESD resistance exceeding 10kV (HBM), reducing the number of components required.

As the number of HDMI-compatible devices increases comes a demand for more input terminals. ROHM meets this growing need by providing for a greater number of terminals. Memory is also integrated for recording image and sound metadata called EDID (Extended Display Identification Data), contributing to greater space savings.