a
FEATURES
Four 10-Bit DACs in One Package
Serial and Parallel Loading Facilities Available
AD7804 Quad 10-Bit Serial Loading
AD7805 Quad 10-Bit Parallel Loading
AD7808 Octal 10-Bit Serial Loading
AD7809 Octal 10-Bit Parallel Loading
+3.3 V to +5 V Operation
Power-Down Mode
Power-On Reset
Standby Mode (All DACs/Individual DACs)
Low Power All CMOS Construction
10-Bit Resolution
Double Buffered DAC Registers
Dual External Reference Capability
APPLICATIONS
Optical Disk Drives
Instrumentation and Communication Systems
Process Control and Voltage Setpoint Control
Trim Potentiometer Replacement
Automatic Calibration
GENERAL DESCRIPTION
+3.3 V to +5 V Quad/Octal 10-Bit DACs
AD7804/AD7805/AD7808/AD7809*
FUNCTIONAL BLOCK DIAGRAMS
AV
DD
DV
DD
REFOUT
REFIN
AV
DD
DIVIDER
COMP
CHANNEL D
CONTROL REG
DATA
REGISTER
V
BIAS
DAC C
DAC
REGISTER
MUX
1.23V REF
AGND DGND
V
OUT
F*
POWER ON
RESET
AD7804/
AD7808
V
BIAS
DAC D
V
OUT
E*
V
OUT
D
MUX
V
OUT
C
CHANNEL C
CONTROL REG
DATA
REGISTER
V
BIAS
MUX
DAC
REGISTER
DAC B
V
OUT
B
CHANNEL B
CONTROL REG
DATA
REGISTER
V
BIAS
DAC
REGISTER
MUX
DAC A
V
OUT
A
PD**
CHANNEL A
CONTROL REG
SYSTEM
CONTROL REG
DATA
REGISTER
DAC
REGISTER
V
OUT
H*
The AD7804/AD7808 are quad/octal 10-bit digital-to-analog
converters, with serial load capabilities, while the AD7805/AD7809
are quad/octal 10-bit digital-to-analog converters with parallel
load capabilities. These parts operate from a +3.3 V to +5 V
(±10%) power supply and incorporates an on-chip reference.
These DACs provide output signals in the form of V
BIAS
±
V
SWING
.
V
SWING
is derived internally from V
BIAS
. On-chip control registers
include a system control register and channel control registers.
The system control register has control over all DACs in the
package. The channel control registers allow individual control
of DACs. The complete transfer function of each individual
DAC can be shifted around the V
BIAS
point using an on-chip
Sub DAC. All DACs contain double buffered data inputs,
which allow all analog outputs to be simultaneously updated
using the asynchronous LDAC input.
Control Features
Hardware Clear
System Control
Power Down
1
System Standby
2
System Clear
Input Coding
Channel Control
Channel Standby
2
Channel Clear
V
BIAS
Channels Controlled
All
All
All
All
All
Selective
Selective
Selective
Main DAC
Sub DAC
FSIN
CLKIN
SDIN
INPUT SHIFT
REGISTER &
CONTROL LOGIC
V
OUT
G*
CLR LDAC
**ONLY
AD7804 SHOWN FOR CLARITY
**SHOWS
ADDITIONAL CHANNELS ON THE AD7808
**PIN ON THE AD7808 ONLY
AV
DD
DV
DD
REFOUT
REFIN
AV
DD
DIVIDER
COMP
CHANNEL D
CONTROL REG
1.23V REF
AGND DGND
V
OUT
F*
POWER ON
RESET
AD7805/
AD7809
V
BIAS
DAC D
V
OUT
E*
MUX
V
OUT
D
DATA
REGISTER
V
BIAS
DAC
REGISTER
MUX
DAC C
V
OUT
C
CHANNEL C
CONTROL REG
DATA
REGISTER
V
BIAS
MUX
DAC
REGISTER
DAC B
V
OUT
B
CHANNEL B
CONTROL REG
DATA
REGISTER
V
BIAS
MUX
DAC
REGISTER
DAC A
V
OUT
A
PD**
CHANNEL A
CONTROL REG
SYSTEM
CONTROL REG
DATA
REGISTER
DAC
REGISTER
V
OUT
H*
INPUT
REGISTER
V
OUT
G*
CS
WR
CONTROL
LOGIC
NOTES
1
Power-down function powers down all internal circuitry including the reference.
2
Standby functions power down all circuitry except for the reference.
MODE A0 A1 A2**
DB9 DB2 DB1 DB0
CLR LDAC
**ONLY
AD7805 SHOWN FOR CLARITY
**SHOWS
ADDITIONAL CHANNELS ON THE AD7809
**PIN ON THE AD7809 ONLY
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.
*Patent
pending.
Index on Page 26.
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., 1998
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