a
Octal, 13-Bit Voltage-Output DAC
with Parallel Interface
AD7838
FEATURES
Eight 13-Bit DACs in One Package
Full 13-Bit Performance without Adjustments
Buffered Voltage Outputs
Offset Adjust for Each DAC Pair
؎5 V Supply Operation
Unipolar or Bipolar Output Swing to ؎4.5 V
Output Settling to 1/2 LSB in 5 s
Double Buffered Digital Inputs
Microprocessor and TTL/CMOS Compatible
Asynchronous Load Facility using LDAC Inputs
Clear Function to User-Defined Voltage
Power-On-Reset, Outputs Power Up at DUTGND
44-Lead PLCC Package
Pin Compatible with MAX547
REF AB REF CD REF EF REF GH
AD7838
INPUT
LATCH A
DAC
LATCH A
INPUT
LATCH B
DAC
LATCH B
DAC B
INPUT
LATCH C
DAC
LATCH C
DAC C
INPUT
LATCH D
DAC
LATCH D
DAC D
INPUT
LATCH E
DAC
LATCH E
DAC E
INPUT
LATCH F
DAC
LATCH F
DAC F
INPUT
LATCH G
DAC
LATCH G
The AD7838 contains eight 13-bit, voltage-output digital-toanalog converters (DACs). The output voltages are provided
through on-chip precision output amplifiers into which an external offset voltage can be inserted via the DUTGND pins. The
AD7838 operates from a ± 5 V ± 5% supply. Bipolar output
voltages with up to ± 4.5 V voltage swing can be achieved with
no external components. The AD7838 has four separate reference inputs; each is connected to two DACs, providing different
scale output voltages for every DAC pair.
DAC G
INPUT
LATCH H
DAC
LATCH H
The AD7838 features double-buffered interface logic with a 13bit parallel data bus. Each DAC has an input latch and a DAC
latch. Data in the DAC latch sets the output voltage. The eight
input latches are addressed with three address lines. Data is
loaded to the input latch with a single write instruction. An
asynchronous LDAC input transfers data from the input latch to
the DAC latch. The four LDAC inputs each control two DACs,
and all DAC latches can be updated simultaneously by asserting
VOUT A
DAC A
DAC H
RY
A L
IN A
IM IC
EL HN
PR EC TA
T DA
APPLICATIONS
Process Control
Automatic Test Equipment
General Purpose Instrumentation
Digital Offset and Gain Adjustment
Arbitrary Function Generators
Avionics Equipment
GENERAL DESCRIPTION
FUNCTIONAL BLOCK DIAGRAM
DUTGND
AB
VOUT B
VOUTC
DUTGND
CD
VOUT D
D12
D0
CS
WR
LDACAB
LDACCD
LDACEF
LDACGH
VOUT F
VOUT G
DUTGND
GH
VOUT H
POWER ON
RESET
CONTROL LOGIC
A0–A2
VOUT E
DUTGND
EF
CLR
VSS
VDD
GND
all LDAC pins. An asynchronous clear input resets the output
of all eight DACs to the relevant DUTGND. Asserting CLR
resets both the DAC and the input latch to bipolar zero (1000
Hex). On power-up, reset circuitry performs the same function
as CLR. All logic inputs are TTL/CMOS compatible.
The AD7838 is available in a 44-lead PLCC package.
REV. 0
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: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
