Intersil:ISL59451 - Triple 4:1 DC Restored Single Supply Video Multiplexing Amplifier

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 amplifier¡¯s 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 -40¡ãC to +85¡ãC extended temperature range.

• Complete Video Level DC Restoration System
• 250MHz Bandwidth (GAIN = 1)
• +5V Single Supply Operation
• Capable of Pixel Rate Channel Switching
• TTL/CMOS Compatible Keyed Clamp Control
• High Impedance Output Setting
• 150¦¸ Output Load Capability for Video Cable Driving
• Ideal for RGB/YPbPr/S-Video/Composite Video Signals
• Pb-Free (RoHS Compliant)