DAC8221:  Dual 12-Bit Buffered Multiplying CMOS D/A Converter

The DAC-8221 combines two identical 12-bit, multiplying, digital-to-analog converters into a single CMOS chip. This device is electrically similar to DAC-8212 with improved microprocessor interface timing and is packaged in a narrow 0.300" DIP. Monolithic construction offers excellent DAC-to-DAC matching and tracking over the full ioperating temperature range. The DAC-8221 consists of two thin-film R-2R resistor-ladder networks, two 12-bit data latches, one 12-bit input buffer, and control logic. The DAC-8221 operates on a single supply from +5V to +15V. Maximum power dissipation with 0V and +5V logic levels and a +5V supply is less than 0.5mW. The DAC-8221 is manufactured using PMI's highly-stable, thin film resistors on an advanced oxide-isolated, silicon-gate, CMOS process. PMI's improved latch-up resistant design eliminates the need for external protective Schottky diodes.

A common 12-bit (TTL/CMOS compatible) input port is used to load a 12-bit-wide word into either of the two DACs. This port, whose data loading is similar to that of a RAM's write cycle, interfaces directly with most 12-bit or wider bus systems. With WR and CS lines at logic LOW, the input data registers are transparent. This allows direct unbuffered data to flow directly to the DAC output selected by DAC A/DAC B control input.