LC2MOS
16-Bit Voltage Output DAC
AD7846
FUNCTIONAꢀ BꢀOCK DIAGRAM
FEATURES
V
V
CC
DD
16-bit monotonicity over temperature
2 ꢀSBs integral linearity error
Microprocessor compatible with readback capability
Unipolar or bipolar output
Multiplying capability
ꢀow power (100 mW typical)
21
4
V
REF+
7
AD7846
R
R
R
R
R
6
5
R
IN
A2
A1
16
SEGMENT
SWITCH
MATRIX
V
A3
OUT
12-BIT DAC
12
23
CS
V
REF–
8
DAC LATCH
12
22
25
24
4
R/W
CONTROL
LOGIC
LDAC
CLR
I/O LATCH
9
10
3
20
V
DB15 DB0
DGND
SS
Figure 1.
GENERAꢀ DESCRIPTION
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).
W
to 00…000 or 10…000 depending on the state of R/ . 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.
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.
PRODUCT HIGHꢀIGHTS
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.
In addition to the excellent accuracy specifications, the AD7846
also offers a comprehensive microprocessor interface. There are
3. Power Dissipation
CS W LDAC
CLR
16 data I/O pins, plus control lines ( , R/
,
and
allow writing to and reading from the I/O latch.
This is the readback function, which is useful in ATE applications.
).
Power dissipation of 100 mW makes the AD7846 the
lowest power, high accuracy DAC on the market.
W
CS
R/ and
LDAC
allows simultaneous updating of DACs in a multi-DAC
CLR
system and the
line will reset the contents of the DAC latch
Rev. G
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