LCMOS 16-Bit Voltage Output DAC

The AD7846 is a 16-bit DAC constructed with the Analog Devices, Inc., LC2MOS 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.

This means that the DAC output can be reset to 0 V in both the unipolar and bipolar configurations.

The AD7846 is available in 28-lead plastic, ceramic, and PLCC packages.

Product Highlights

* 16-Bit Monotonicity

The guaranteed 16-bit monotonicity over temperature makes the AD7846 ideal for closed-loop applications.

* Readback

The ability to read back the DAC register contents minimizes software routines when the AD7846 is used in ATE systems.

* Power Dissipation

Power dissipation of 100 mW makes the AD7846 the lowest power, high accuracy DAC on the market.

* 16-bit monotonicity over temperature

* ±2 LSBs integral linearity error

* Microprocessor compatible with readback capability

* Unipolar or bipolar output

* Multiplying capability

* Low power (100 mW typical)