The AD7249 DACPORT contains a pair of 12-bit， voltageoutput， digital-to-analog converters with output amplifiers and Zener voltage reference on a monolithic CMOS chip. No external trims are required to achieve full specified performance. The output amplifiers are capable of developing +10 V across a 2 k? load. The output voltage ranges with single supply operation are 0 V to +5 V or 0 V to +10 V， while an additional bipolar ±5 V output range is available with dual supplies. The ranges are selected using the internal gain resistor. Interfacing to the AD7249 is serial， minimizing pin count and allowing a small package size. Standard control signals allow interfacing to most DSP processors and microcontrollers. The data stream consists of 16 bits， DB15 to DB13 are don’t care bits， the 13th bit （DB12） is used as the channel select bit and the remaining 12 bits （DB11 to DB0） contain the data to update the DAC. The 16-bit data word is clocked into the input register on each falling SCLK edge. The data format is natural binary in both unipolar ranges， while either offset binary or twos complement format may be selected in the bipolar range. A CLR function is provided which sets the output to 0 V in both unipolar ranges and in the twos complement bipolar range， while with offset binary data format， the output is set to –REFIN. This function is useful as a power-on reset as it allows the outputs to be set to a known voltage level. The AD7249 features a serial interface which allows easy connection to both microcomputers and 16-bit digital signal processors with serial ports. The serial data may be applied at rates up to 2 MHz allowing a DAC update rate of 125 kHz. The AD7249 is fabricated on linear compatible CMOS （LC2 MOS）， an advanced， mixed technology process. It is packaged in 16-lead DIP and 16-lead SOIC packages.