The AD664 is a monolithic IC that integrates four complete 12-bit, voltage-output DACs. Each DAC features a dual-buffer input latch and data readback. All DAC read/write operations are done through a single-ended microprocessor-compatible I/O port.
This I/O port can handle 4-bit, 8-bit, or 12-bit parallel words, allowing for easy interfacing with a variety of microprocessors. The device has a reset-to-zero control pin that allows the user to reset all DAC outputs to zero at the same time, regardless of what's in the input latch. Any or all DACs can be placed in transparency mode so that the output can react immediately to the input data.
The analog portion of the AD664 consists of 4 DAC units, 4 output amplifiers, 1 control amplifier, and multiple switches. Each DAC unit is of the reversed-phase R-2R type. The output current of each DAC is switched to the on-chip application resistor and output amplifier. The output range of each DAC unit is programmed via a digital I/O port and can be set to a unipolar or bipolar range with a gain of 1x or 2 times the reference voltage. All DACs operate on an external reference.
The AD664's comprehensive capabilities are the result of using Analog Devices' BiMOS II process combined with laser-adjusted thin film resistors and double-layer metal interconnects.