Sunnyvale, Calif. Maxim Integrated Products Inc. claims that using this four-channel video switch instead of using traditional integrated audio/video switching devices can save money.
This device is actually a video buffer with switching on the input to switch between two video sources, and a reconstruction filter on the output, the company said.
The video switch filters and buffers composite video broadcast signal (CVBS) and RGB video signals, which makes it suited for European dual-standard audio/video TV connector (SCART) set-top boxes with a VCR loop-through.
Today, all audio and video switching in European set-top boxes (STBs) utilize a costly integrated audio/video (A/V) switch with high-end features, such as volume control and high audio drive capability. A more cost-effective alternative would be to use Maxim's video switch, along with low-cost standard analog switches for the audio switching. The cost of this latter approach is 50 percent less than using integrated A/V switching devices, according to Maxim.
The video switch is used in anti-aliasing and digital-to-analog converter (D/A converter)-smoothing video applications or wherever analog video is reconstructed from a digital data stream, such as cable/satellite/terrestrial STBs, DVD players, hard disk recorders (HDR), and personal video recorders (PVRs).
The device uses a continuous-time; Butterworth-type-response lowpass filter to
attenuate the sampling frequency of the D/A converter encoder. All video signal-timing extraction and clamping are done within the device.
The video switch operates from a single +5 V supply and has a flat
passband out to 5 MHz, which is practical for PAL video signals with a stopband of -41 dB at 27 MHz. The output buffer has a fixed gain of +6 dB capable of driving two standard video loads with a 2-V peak to peak signal. Output disable control is also through an external pin.
The MAX7457 is available in an extended temperature range (-40°C to +85°C), with prices starting at $1.62 (1,000 up, FOB USA). Click here for the MAX7457 data sheet.
Maxim Integrated Products, 1-800-998-8800, www.maxim-ic.com.