Low-Power Video Switches for Dual SCART Connectors

Active: In Production.

The MAX9655/MAX9656 dual SCART switches route video signals between a set-top box decoder chip and two external SCART connectors. Under the control of the TV_SEL logic input, the MAX9655 selects whether the CVBS and RGB signals from the encoder or the VCR SCART are routed to the TV SCART. The CVBS signal from the encoder is always routed to the VCR SCART.

The MAX9656 is similar to the MAX9655 except that under the control of the VCR_SEL logic input, the MAX9656 selects whether the CVBS signal from the encoder or the TV SCART is routed to the VCR SCART. The MAX9656 also features a low-power shutdown mode, in which quiescent current falls to 35µA.

The incoming video signals must be AC-coupled to the inputs, which have sync-tip clamps to set the internal DC level. After the input stages, multiplexers select which video signals are routed to the reconstruction filters and output amplifiers. The reconstruction filters are optimized for standard-definition signals and typically have ±1dB passband flatness out to 9.5MHz and 47dB attenuation at 27MHz.

The amplifiers have 2V/V gain, and the outputs can be DC-coupled to a 75Ω load, which is the equivalent of two video loads, or AC-coupled to a 150Ω load.

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