AD774B

The AD674B and AD774B are complete 12-bit successive approximation analog-to-digital converters with three-state output buffer circuitry for direct interface to 8- and 16-bit microprocessor busses. A high precision voltage reference and clock are included on chip, and the circuit requires only power supplies and control signals for operation.

The AD674B and AD774B are pin compatible with the industry standard AD574A, but offer faster conversion time and access speed than the AD574A and lower power consumption. The AD674B converts in 15 µs (maximum) and the AD774B converts in 8 µs (maximum).

The monolithic 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. Offset linearity and scaling errors are minimized by active trimming of thin-film resistors.

Five different grades are available. The J and K grades are specified for operation over the 0°C to +70°C temperature range. A and B grades are specified from -40°C to +85°C, the T is specified from -55°C to +125°C. The J and K grades are available in a 28-pin plastic DIP or 28-lead SOIC. All other grades are available in a 28-pin hermetically sealed ceramic DIP.

PRODUCT HIGHLIGHTS

1. Industry Standard Pinout: The AD674B and AD774B use the pinout established by the industry standard AD574A.
2. Analog Operation: The precision, laser-trimmed scaling and bipolar offset resistors provide four calibrated ranges: 0 V to 10 V and 0 V to 20 V unipolar; –5 V to +5 V and –10 V to +10 V bipolar. The AD674B and AD774B operate on +5 V and ±12 V or ±15 V power supplies.
3. Flexible Digital Interface: On-chip multiple-mode three-state output buffers and interface logic allow direct connection to most microprocessors. The 12 bits of output data can be read either as one 12-bit word or as two 8-bit bytes (one with 8 data bits, the other with 4 data bits and 4 trailing zeros).
4. The internal reference is trimmed to 10.00 V with 1% maximum error and 10 ppm/°C typical temperature coefficient. The reference is available externally and can drive up to 2.0 mA beyond the requirements of the converter and bipolar offset resistors.
5. The AD674B and AD774B are available in versions compliant with MIL-STD-883. Refer to the Analog Devices Military Products Databook or current AD674B / AD774B / 883B data sheet for detailed specifications.