AD7837 Datasheet, PDF (1/13 Pages) Analog Devices – LC2MOS Complete, Dual 12-Bit MDACs

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LC²MOS
Complete, Dual 12-Bit MDACs
AD7837/AD7847
FEATURES
Two 12-Bit MDACs with Output Amplifiers
4-Quadrant Multiplication
Space-Saving 0.3", 24-Lead DIP and 24-Terminal
SOIC Package
Parallel Loading Structure: AD7847
(8 + 4) Loading Structure: AD7837
APPLICATIONS
Automatic Test Equipment
Function Generation
Waveform Reconstruction
Programmable Power Supplies
Synchro Applications
GENERAL DESCRIPTION
The AD7837/AD7847 is a complete, dual, 12-bit multiplying
digital-to-analog converter with output amplifiers on a mono-
lithic CMOS chip. No external user trims are required to
achieve full specified performance.
Both parts are microprocessor compatible, with high speed data
latches and interface logic. The AD7847 accepts 12-bit parallel
data which is loaded into the respective DAC latch using the
WR input and a separate Chip Select input for each DAC. The
AD7837 has a double-buffered 8-bit bus interface structure
with data loaded to the respective input latch in two write opera-
tions. An asynchronous LDAC signal on the AD7837 updates
the DAC latches and analog outputs.
The output amplifiers are capable of developing ± 10 V across a
2 kΩ load. They are internally compensated with low input off-
set voltage due to laser trimming at wafer level.
The amplifier feedback resistors are internally connected to
V_OUT on the AD7847.
The AD7837/AD7847 is fabricated in Linear Compatible CMOS
(LC²MOS), an advanced, mixed technology process that com-
bines precision bipolar circuits with low power CMOS logic.
A novel low leakage configuration (U.S. Patent No. 4,590,456)
ensures low offset errors over the specified temperature range.
FUNCTIONAL BLOCK DIAGRAMS
V_DD
AD7837
V_REFA
V_REFB
DB0
DB7
LDAC
CS
WR
A0
A1
CONTROL
LOGIC
DGND
MS INPUT
LATCH
LS INPUT
LATCH
4
8
DAC LATCH A
12
DAC A
DAC B
12
DAC LATCH B
4
8
MS INPUT
LATCH
LS INPUT
LATCH
R_FBA
V_OUTA
AGNDA
R_FBB
V_OUTB
AGNDB
V_SS
V_DD
AD7847
V_REFA
V_REFB
DB0
DB11
WR
CSA
CSB
CONTROL
LOGIC
DAC LATCH A
DAC A
DAC B
DAC LATCH B
V_OUTA
AGNDA
V_OUTB
AGNDB
DGND
V_SS
PRODUCT HIGHLIGHTS
1. The AD7837/AD7847 is a dual, 12-bit, voltage-out MDAC
on a single chip. This single chip design offers considerable
space saving and increased reliability over multichip designs.
2. The AD7837 and the AD7847 provide a fast versatile inter-
face to 8-bit or 16-bit data bus structures.
REV. C
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© Analog Devices, Inc., 2000