The DAC-8221 integrates two identical 12-bit multiplication digital-to-analog converters in a single CMOS chip. The device has similar electrical performance to the DAC-8212 with improved microprocessor interface timing performance in a narrow 0.300" DIP package. The single-chip structure provides good DAC-DAC matching and tracking capabilities over the entire operating temperature range. The DAC-8221 consists of two thin-film R-2R resistor trapezoidal networks, two 12-bit data latches, one 12-bit input buffer, and control logic. The DAC-8221 operates from a single supply with a voltage range of +5V to +15V. When the logic levels are 0V and +5V and the supply voltage is +5V, the maximum power consumption is less than 0.5mW. The DAC-8221 is based on an advanced oxide-isolated, silicon-gate CMOS process and is made with PMI's highly stable thin-film resistors. The PMI improved anti-latch design eliminates the need for external protection Schottky diodes.
A common 12-bit (TTL/CMOS compatible) input 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 systems or wider bus systems. When the WR and CS lines are logically low, the input data registers are transparent. This allows direct unbuffered data to flow directly to the DAC output selected by the DAC A/DAC B control input.