a
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)
V
REF +
R
LC MOS
16-Bit Voltage Output DAC
AD7846
FUNCTIONAL BLOCK DIAGRAM
V
CC
V
DD
2
AD7846
A2
16
SEGMENT
SWITCH
MATRIX
R
R
R
IN
R
A3
12-BIT DAC
A1
12
DAC LATCH
V
OUT
R
V
REF –
4
CS
CONTROL
LOGIC
R/
W
LDAC
CLR
12
I/O LATCH
V
SS
DB15 DB0
DGND
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
The AD7846 is a 16-bit DAC constructed with Analog Devices’
LC
2
MOS process. It has V
REF+
and V
REF–
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 4 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 applica-
tions.
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.
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.
REV. E
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
AD [ ANALOG DEVICES ]
