ISL59451

Description

The ISL59451 is a 4-input, single-supply triple video multiplexer. It features a DC restore function that makes it ideally suited for single-supply AC-coupled component video applications where amplifier headroom is a concern. When logic 0 is applied to CLAMP, the sample-hold amplifier loop is closed and the DC level of the amplifier output is set to the corresponding reference level. This can occur during sync, or at any time that a black level is expected. When logic 1 is applied to CLAMP, the clamp is disabled and the correcting voltage is stored on each video amplifiers input coupling capacitor. This DC reference condition is maintained during the active video period. The restored DC voltage level can be adjusted over a range of 0V to +3V using external reference voltages applied to the REF_G and REF_RB pins. The device features a TTL/CMOS logic compatible gain select pin (AV2) of x1 or x2. When HIZ is pulled high, the outputs are put into high-impedance states and the video inputs are disconnected. This is an essential feature for power sensitive applications. The ISL59451 also features channel-switching at pixel rates to allow for video overlays. The ISL59451 operates from a single +5V supply and is ideal for +5V systems when used with sync separators such as the EL1883. The red and blue channels share a common reference pin (REF_RB) which can also be used to adjust chroma offsets in YPbPr systems. The green channel has a separate reference pin (REF_G), which can be used to accommodate sync-on-green or luma. The ISL59451 is comes in a 32 Ld QFN package and is specified for operation over the -40C to +85C extended temperature range.