A three-channel, 12-bit Contact Image Sensor (CIS) or Charged Coupled Device (CCD) signal processor, with the lowest cost design and lowest noise performance available for consumer and mass market scanners and copiers, has been introduced by EXAR Corporation .

The XRD9827 includes a high-speed 12-bit A/D converter for low-cost, high-throughput operation. The conversion rate of 6 MSPS is the fastest available, while the three-channel input for RGB 600, 1000 or 1,200 DPI MUX is faster than any available today. The selectable 6- or 8-bit data bus permits optimal I/O interconnects to the ASIC or DSP. The device is ideal for color sheet-fed and flatbed scanners, multifunction products (scanners combining copier and fax functions), digital color copiers, and other low-cost data acquisition devices. With the prior announcement of the XRD9812 (4/20/98), Exar now has two families of high-performance video imaging subsystems available.

According to John Sramek, group vice president and general manager of EXAR's Video and Imaging Division, "Reducing both the number of CDS and PGA components and pin counts have enabled us to improve both the speed and performance of the XRD9827. We are able to bring it to market for less than any other competitive device available. In addition, it requires less external components. The part is another in our growing portfolio of CIS/CCD processors that increase the resolution, speed and functional integration of devices in the cost-sensitive scanner market."

According to compiled material by the Government of Taiwan, estimates show that the number of scanners shipped will grow from 6 million units in 1996 to 27 million units in 2000, for a compound annual growth rate in excess of 45 percent.

The XRD9827 at 200 mW at typical 5V, making it ideal for Universal Serial Bus (USB) devices. Market research firm Dataquest estimates that 5 percent of scanners reaching the market in 1998 will have the USB, increasing to 25 percent in 1999, a 500 percent increase year-to-year.

Technical Description

The XRD9827 is optimized for interfacing a CIS sensor to an ASIC or DSP, with no redundant functions, and has very flexible and programmable input coupling and black level correction capabilities.

In CIS mode, input can be AC coupled, enabling CIS signals with black levels to be referenced to ground and then level-shifted internally to correspond to VRB. For CIS sensors without black reference, the clamp switch can be disabled in the DC coupled mode. The CIS signal is level-shifted to VRB in order to use the full range of the A/D. The CIS DC coupled mode can also be used in other A/D applications that do not require a CDS function, but require programmable gain and offset.

In CCD mode, an internal clamp sets the proper black level for CCD outputs. The outputs are TTL and CMOS compatible. The device can be operated in the 10-12 MHz range.

Remember that most of the marketing in color scanner equipment is hype before you go read specifications of products involved in that market. If you have been following these pages you will know that a 12-bit ADC in the channel will inevitably end up as an 8-bit data stream for the PC as it goes down to 10 for processing and then to 8 through the gamma lookup tables to suit most of the manipulation software that is out there.

The same is true of resolutions. Most users will reduce their scans to 150 dpi simply because of the throughput time of processing and the I/O of the PC itself -- an impossible-to-control number from outside the computer.

However, there is a market for the really top end stuff -- but not the 27 million units for the Year 2000 -- if you get away from the $69 machines that are currently on offer in the market. And this part is right up there in challenging that end of the market. For that market this would be an extremely low-priced part with 12-bit, 1200 dpi and 6-MHz processing. But, of course, that is not the market that Exar is aiming for: The parts will simply not be used to their full potential but will provide fodder for the carton that the OEM ships the low-cost scanner in, hoping to distance himself from his competitors by somewhere from a few to ten dollars a box.

The XRD9827 is in production in a 20-pin SOIC and is priced at $2.50 in 1000-piece lots.