The AD7846 is a 16-bit DAC constructed with the Analog Devices， Inc.， LC2 MOS process. It has VREF+ and VREF? reference inputs and an on-chip output amplifier. These can be configured to give a unipolar output range （0 V to +5 V， 0 V to +10 V） or bipolar output ranges （±5 V， ±10 V）。 The DAC uses a segmented architecture. The four MSBs in the DAC latch select one of the segments in a 16-resistor string. Both taps of the segment are buffered by amplifiers and fed to a 12-bit DAC， which provides a further 12 bits of resolution. This architecture ensures 16-bit monotonicity. Excellent integral linearity results from tight matching between the input offset voltages of the two buffer amplifiers. In addition to the excellent accuracy specifications， the AD7846 also offers a comprehensive microprocessor interface. There are 16 data I/O pins， plus control lines （CS， R/W， LDAC and CLR）。 R/W and CS allow writing to and reading from the I/O latch. This is the readback function， which is useful in ATE applications. LDAC allows simultaneous updating of DACs in a multi-DAC system and the CLR line will reset the contents of the DAC latch to 00…000 or 10…000 depending on the state of R/W.