The DAC-8222 is a dual-channel 12-bit dual-buffered CMOS digital-to-analog converter. The device has a 12-bit wide data port that supports direct loading of 12-bit data words. This design allows for faster throughput times in standalone systems or when interfaced with 16-bit processors. A common 12-bit input TTL/CMOS-compatible data port is used to load a 12-bit wide data word into one of the two DACs. The data loading structure of this port is similar to the write cycle of RAM and interfaces directly with most 12-bit and 16-bit bus systems. (See PMI DAC-8248 for a complete 8-bit data bus interface product.) The common bus design allows the DAC-8222 to be available in a 24-pin 0.3" DIP narrow body package, which helps save PCB space.
The DAC is controlled by two signals, WR and LDAC. At these inputs, when the logic is low, the DAC registers become transparent. This allows direct unbuffered data to flow directly to the DAC output selected by DAC A/DAC B. In addition, the DAC's dual buffered digital inputs allow two DACs to update simultaneously.
DAC8222 single-chip construction provides good DAC-DAC matching and tracking capabilities over the entire operating temperature range. The chip consists of two thin-film R-2R resistor trapezoidal networks, four 12-bit registers, and DAC control logic circuitry. The device is configured with independent reference input and feedback resistors for each DAC and operates from a single supply with a voltage range of +5 V to +15 V. When the supply voltage is +5 V and the logic level is zero or VDD, the power consumption is less than 0.5 mW.
DAC8222 is based on an advanced oxide-isolated, silicon gate CMOS process made with PMI's highly stable thin-film resistors. The PMI improved anti-latch design eliminates the need for external protection Schottky diodes.