16-Bit Voltage Output DAC

AD7846

Rev. G

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FEATURES

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)

FUNCTIONAL BLOCK DIAGRAM

A2

A1

A3

16

SEGMENT

SWITCH

MATRIX

R

R

R

12-BIT DAC

DAC LATCH

I/O LATCH

CONTROL

LOGIC

AD7846

R

21

4

7

8

9

6

5

23

22

25

24

R

DGND

CLR

LDAC

R/W

CS

4

12

12

DB15 DB0

10

3

20

Figure 1.

GENERAL DESCRIPTION

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

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

1.

16-Bit Monotonicity

The guaranteed 16-bit monotonicity over temperature

makes the AD7846 ideal for closed-loop applications.

2.

Readback

The ability to read back the DAC register contents

minimizes software routines when the AD7846 is used in

ATE systems.

3.

Power Dissipation

Power dissipation of 100 mW makes the AD7846 the

lowest power, high accuracy DAC on the market.