a
FEATURES
Low Cost
Replaces Eight Potentiometers
Eight Individually Programmable Outputs
Three-Wire Serial Input
Power Shutdown ≤ 25 W Including IDD and IREF
Midscale Preset, AD8801
Separate V REFL Range Setting, AD8803
+3 V to +5 V Single Supply Operation
Octal 8-Bit TrimDAC
with Power Shutdown
AD8801/AD8803
FUNCTIONAL BLOCK DIAGRAM
(DACs 2–7 Omitted for Clarity)
VREFH
AD8801/AD8803
8
VDD
CK RS
DAC
SELECT
APPLICATIONS
Automatic Adjustment
Trimmer Potentiometer Replacement
Video and Audio Equipment Gain and Offset Adjustment
Portable and Battery Operated Equipment
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3
CS
O1
8
1
11-BIT
SERIAL 8
LATCH
SDI
D
CK RS
8
GENERAL DESCRIPTION
Easily programmed by serial interfaced microcontroller ports,
the AD8801 with its midscale preset is ideal for potentiometer
replacement where adjustments start at a nominal value. Applications such as gain control of video amplifiers, voltage controlled frequencies and bandwidths in video equipment,
geometric correction and automatic adjustment in CRT computer graphic displays are a few of the many applications ideally
suited for these parts. The AD8803 provides independent control of both the top and bottom end of the potentiometer divider
allowing a separate zero-scale voltage setting determined by the
VREFL pin. This is helpful for maximizing the resolution of devices with a limited allowable voltage control range.
DAC 1 VOUT
VREFL
8
ADDRESS
CLK
The AD8801/AD8803 provides eight digitally controlled dc
voltage outputs. This potentiometer divider TrimDAC® allows
replacement of the mechanical trimmer function in new designs.
The AD8801/AD8803 is ideal for dc voltage adjustment
applications.
VREFH
8-BIT
LATCH
GND
VREFL
8-BIT 8
LATCH
CK RS
RS
VREFH
DAC 8 VOUT
VREFL
O8
8
SHDN
Internally the AD8801/AD8803 contain eight voltage output
digital-to-analog converters, sharing a common reference voltage input.
Each DAC has its own DAC register that holds its output state.
These DAC registers are updated from an internal serial-to-parallel shift register that is loaded from a standard three-wire serial
input digital interface. Eleven data bits make up the data word
clocked into the serial input register. This data word is decoded
where the first 3 bits determine the address of the DAC register
to be loaded with the last 8 bits of data. The AD8801/AD8803
consumes only 5 µA from 5 V power supplies. In addition, in
shutdown mode reference input current consumption is also reduced to 5 µA while saving the DAC latch settings for use after
return to normal operation.
The AD8801/AD8803 is available in 16-pin plastic DIP and the
1.5 mm height SO-16 surface mount packages.
See the AD8802/AD8804 for a twelve channel version of this product.
TrimDAC is a registered trademark of Analog Devices, Inc.
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
