The AD1674 is a complete， multipurpose， 12-bit analog-todigital converter， consisting of a user-transparent onboard sample-and-hold amplifier （SHA）， 10 volt reference， clock and three-state output buffers for microprocessor interface. The AD1674 is pin compatible with the industry standard AD574A and AD674A， but includes a sampling function while delivering a faster conversion rate. The on-chip SHA has a wide input bandwidth supporting 12-bit accuracy over the full Nyquist bandwidth of the converter. The AD1674 is fully specified for ac parameters （such as S/（N+D） ratio， THD， and IMD） and dc parameters （offset， full-scale error， etc.）。 With both ac and dc specifications， the AD1674 is ideal for use in signal processing and traditional dc measurement applications. The AD1674 design is implemented using Analog Devices’ BiMOS II process allowing high performance bipolar analog circuitry to be combined on the same die with digital CMOS logic. Five different temperature grades are available. The AD1674J and K grades are specified for operation over the 0°C to +70°C temperature range. The A and B grades are specified from –40°C to +85°C; the AD1674T grade is specified from –55°C to +125°C. The J and K grades are available in both 28-lead plastic DIP and SOIC. The A and B grade devices are available in 28-lead hermetically sealed ceramic DIP and 28-lead SOIC. The T grade is available in 28-lead hermetically sealed ceramic DIP.