Analog Devices introduced the AD9483, a triple 8-bit analog-to-digital converter (ADC) that has been optimized for digitizing RGB graphics signals from personal computers and workstations. With a 140-MSPS encode rate and full-power analog bandwidth of 300 MHz, the AD9483 can support display resolutions up to 1280 x 1024 at 75 Hz, with sufficient input bandwidth to accurately acquire and digitize each pixel. These features, along with a 1-volt peak-to-peak analog input range and low power dissipation (less than 1.5 watt at +5.0 V) makes the AD9483 perfect for RGB graphics processing for LCD monitors, graphics projectors, and plasma display panels.

To minimize the user's system cost and power dissipation, the AD9483 includes an internal +2.5 V reference and track-and-hold circuit. All the user has to do is provide +5 V and an encode clock - that means that no external reference or additional drive circuitry will be needed for many applications.

The encode input of the AD9483 interfaces directly to TTL, CMOS, or positive-ECL logic, and will operate with single-ended or differential inputs. The digital outputs are three-state CMOS and may be powered from either a +3.3-V or a +5-V supply. Depending on the conversion rate required, the user may select either dual-channel or single-channel outputs. The dual (demultiplexed) mode interleaves ADC data through two 8-bit channels at one-half the clock rate. This mode reduces the speed and cost of external digital interfaces while allowing the ADC to be clocked up to the full 140 MSPS conversion rate. The AD9483 also provides users with clock outputs to minimize clock-data skew at these high conversion rates. In the single (non-demultiplexed) mode, all data is piped at the full clock rate to the channel A outputs with a maximum conversion rate of 100 MSPS.

This part looks expensive but when you think about the individual-channel way of doing this conversion you will, in fact, be saving a lot. The specs are exactly what you need for the job: 1-V input, 140-MHz sampling, 300-MHz bandwidth; no messing with scaling inputs, no worrying about decisions to limit scanning standards. The dual-/single-channel output system used here is one we have seen from Analog before and it has been well accepted as an easy method of limiting external data rates while still getting conversions at a high enough speed to get the job done right.

With the internal reference and track-and-hold the OEM designer will have a simple time incorporating this part into his display system. The fact that it is triple-channeled will also ensure that any variations in channel performance -- between R, G and B -- will not likely come from conversion problems. This will be a very profitable part for the company.

The AD9483 is in a 100-pin PQFP and is priced at $25.50 in 1000-piece lots.