LC2MOS
Quad 14-Bit DAC
a
AD7834/AD7835
FEATURES
GENERAL DESCRIPTION
Four 14-Bit DACs in One Package
AD7834—Serial Loading
AD7835—Parallel 8-/14-Bit Loading
Voltage Outputs
The AD7834 and AD7835 contain four 14-bit DACs on one
monolithic chip. The AD7834 and AD7835 have output volt-
ages in the range of ±8.192 V with a maximum span of 14 V.
The AD7834 is a serial input device. Data is loaded in 16-bit
format from the external serial bus, MSB first after two leading
0s, into one of the input latches via DIN, SCLK and FSYNC.
The AD7834 has five dedicated package address pins, PA0–
PA4, that can be wired to AGND or VCC to permit up to 32
AD7834s to be individually addressed in a multipackage
application.
Power-On Reset Function
Max/Min Output Voltage Range of +/–8.192 V
Maximum Output Voltage Span of 14 V
Common Voltage Reference Inputs
User Assigned Device Addressing
Clear Function to User-Defined Voltage
Surface Mount Packages
The AD7835 can accept either 14-bit parallel loading or
double-byte loading, where right-justified data is loaded in one
8-bit and one 6-bit byte. Data is loaded from the external bus
into one of the input latches under the control of the WR, CS,
BYSHF and DAC channel address pins, A0–A2.
AD7834—28-Pin SO, DIP and Cerdip
AD7835—44-Pin PQFP and PLCC
APPLICATIONS
Process Control
Automatic Test Equipment
General Purpose Instrumentation
With either device, the LDAC signal can be used to update
either all four DAC outputs simultaneously or individually,
on reception of new data. In addition, for either device, the
asynchronous CLR input can be used to set all signal outputs,
VOUT1–VOUT4, to the user-defined voltage level on the Device
Sense Ground pin, DSG. On power-on, before the power sup-
plies have stabilized, internal circuitry holds the DAC output
voltage levels to within ±2 V of the DSG potential. As the sup-
plies stabilize, the DAC output levels move to the exact DSG
potential (assuming CLR is exercised).
The AD7834 is available in 28-pin 0.3" SO and 0.6" DIP pack-
ages, and the AD7835 is available in a 44-pin PQFP package
and a 44-pin PLCC package.
AD7835 FUNCTIONAL BLOCK DIAGRAM
AD7834 FUNCTIONAL BLOCK DIAGRAM
V
(–)A
V
V
V
V
(+)A
REF
V
V (–)
V
REF
V
V
(+)
DSG A
REF
CC
DD
SS
CC
DD
SS
REF
INPUT
REGISTER
1
INPUT
REGISTER
1
AD7835
AD7834
DAC 1
LATCH
DAC 1
LATCH
DAC 1
DAC 2
DAC 1
DAC 2
BYSHF
PAEN
X1
X1
X1
X1
V
1
2
V
1
2
OUT
OUT
14
DB13
DB0
PA0
PA1
PA2
PA3
PA4
INPUT
BUFFER
INPUT
REGISTER
2
INPUT
REGISTER
2
DAC 2
LATCH
DAC 2
LATCH
CONTROL
LOGIC
V
V
OUT
OUT
WR
CS
&
ADDRESS
DECODE
INPUT
REGISTER
3
INPUT
REGISTER
3
DAC 3
LATCH
DAC 3
LATCH
DAC 3
DAC 4
DAC 3
DAC 4
X1
X1
V
3
4
X1
X1
V
3
4
OUT
OUT
FSYNC
A0
A1
A2
INPUT
REGISTER
4
INPUT
REGISTER
4
ADDRESS
DECODE
DAC 4
LATCH
DAC 4
LATCH
SERIAL-TO-
PARALLEL
CONVERTER
DIN
V
V
OUT
OUT
CLR
SCLK
CLR
AGND
DGND
DSG
LDAC
DSG B
(+)B
REF
AGND
V
V (–)B
REF
DGND
LDAC
REV. A
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.
© Analog Devices, Inc., 1995
One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A.
Tel: 617/329-4700 Fax: 617/326-8703