AD8803_15 Datasheet, PDF (1/16 Pages) Analog Devices – Octal 8-Bit TrimDAC with Power Shutdown

a
Octal 8-Bit TrimDAC
with Power Shutdown
AD8801/AD8803
FEATURES
Low Cost
Replaces Eight Potentiometers
Eight Individually Programmable Outputs
Three-Wire Serial Input
Power Shutdown ≤ 25 ␮W Including I_DD and I_REF
Midscale Preset, AD8801
Separate V_REFL Range Setting, AD8803
+3 V to +5 V Single Supply Operation
APPLICATIONS
Automatic Adjustment
Trimmer Potentiometer Replacement
Video and Audio Equipment Gain and Offset Adjustment
Portable and Battery Operated Equipment
GENERAL DESCRIPTION
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.
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. Appli-
cations such as gain control of video amplifiers, voltage con-
trolled frequencies and bandwidths in video equipment,
geometric correction and automatic adjustment in CRT com-
puter graphic displays are a few of the many applications ideally
suited for these parts. The AD8803 provides independent con-
trol of both the top and bottom end of the potentiometer divider
allowing a separate zero-scale voltage setting determined by the
V_REFL pin. This is helpful for maximizing the resolution of de-
vices with a limited allowable voltage control range.
FUNCTIONAL BLOCK DIAGRAM
(DACs 2–7 Omitted for Clarity)
VREFH
VREFL
VDD
GND
SDI
CLK
CS
AD8801/AD8803
1
DAC
SELECT
8
ADDRESS
3
11-BIT
SERIAL ₈
LATCH
D
CK RS
8 8-BIT
LATCH
CK RS
8 ^8-BIT 8
LATCH
CK RS
V_REFH
DAC 1 ^VOUT
O1
V_REFL
8
......
V_REFH
DAC 8 ^VOUT
O8
V_REFL
8
RS
SHDN
Internally the AD8801/AD8803 contain eight voltage output
digital-to-analog converters, sharing a common reference volt-
age input.
Each DAC has its own DAC register that holds its output state.
These DAC registers are updated from an internal serial-to-par-
allel 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 re-
duced 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.
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