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Electronic Design

Chip Minimizes Reflections And Compensates For Signal Loss

The High Definition Multimedia Interface (HDMI) is the most commonly used interface to connect HDTV sets and other HD products like DVD players and personal video recorders (PVRs). It uses special connectors and a cable up to 20 meters at speeds to 1.65 Gbits/s. This allows HDTV signals to be transmitted without compression, helping to maintain maximum resolution and fidelity.

The Digital Video Interface (DVI) is an older HDTV video interface for PCs that is still used. The problem is that the relatively long cable and its connectors produce reflections, as does any transmission line. They also introduce significant signal losses. Maxim Integrated Products’ MAX3814 is designed to overcome these problems.

The chip is a cable and pc-board equalizer plus a cable driver for HDMI/DVI digital video inputs and transmission-minimized differential-signaling (TMDS) outputs. Developed by Silicon Image, TDMS is the basis for the HDMI and DVI interface outputs. It can transfer video data at rates up to 165 Mpixels per second.

The MAX3814 absorbs output reflections and compensates for signal losses on 80 inches of FR-4 pc board or up to 20 meters of #24 AWG cable. It also provides 15 dB of signal loss compensation for long cables or pc-board traces. Its 50% higher current mode enables the use of 200-Ω back termination resistors. The equalization technology is the same as that used in the MAX3815.

The chip is fully compatible with HDMI standard 1.3. It includes 50-Ω input terminations. Output amplitude is 1.05 V p-p differential. Jitter is less than 0.2 UI p-p. Because of the MAX3814's 5- by 5-mm size, it can be located right at the HDMI or DVI interface, eliminating the need to separate the input and output connectors for their interface IC as required in other drivers. All four inputs and outputs are identical, simplifying pin assignment and pc-board layout.

The MAX3814 comes in a 32-pin thin quad flat no-lead (TQFN) package. Prices begin at $1.95 for quantities of 1000 or more.

Maxim Integrated Products

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