1-/2-/4-Channel
Digital Potentiometers
AD8400/AD8402/AD8403
FUNCTIONAL BLOCK DIAGRAM
256-position variable resistance device
Replaces 1, 2, or 4 potentiometers
1 kΩ, 10 kΩ, 50 kΩ, 100 kΩ
Power shutdown—less than 5 μA
3-wire,SPI-compatible serial data input
10 MHz update data loading rate
2.7 V to 5.5 V single-supply operation
Qualified for automotive applications
AD8403
VDD
8-BIT 8
LATCH
DAC
SELECT
DGND
CK RS
1
2
8-BIT
LATCH
3
A1, A0 4
10-BIT
SERIAL
LATCH
APPLICATIONS
SDI
Mechanical potentiometer replacement
Programmable filters, delays, time constants
Volume control, panning
Line impedance matching
Power supply adjustment
8
D
SHDN
8
CK RS
2
8-BIT
LATCH
RDAC2
SHDN
8
CK RS
CK Q RS
CLK
8-BIT 8
LATCH
CS
RDAC1
RDAC3
SHDN
RDAC4
CK RS
SHDN
RS
A1
W1
B1
AGND1
A2
W2
B2
AGND2
A3
W3
B3
AGND3
A4
W4
B4
AGND4
SHDN
SDO
01092-001
FEATURES
Figure 1.
GENERAL DESCRIPTION
100
RWA
RWB
75
50
25
0
0
64
128
CODE (Decimal)
192
255
01092-002
RWA(D), RWB(D) (% of Nominal RAB)
The AD8400/AD8402/AD8403 provide a single-, dual-, or
quad-channel, 256-position, digitally controlled variable resistor
(VR) device. 1 These devices perform the same electronic adjustment function as a mechanical potentiometer or variable
resistor. The AD8400 contains a single variable resistor in the
compact SOIC-8 package. The AD8402 contains two independent
variable resistors in space-saving SOIC-14 surface-mount
packages. The AD8403 contains four independent variable
resistors in 24-lead PDIP, SOIC, and TSSOP packages. Each
part contains a fixed resistor with a wiper contact that taps the
fixed resistor value at a point determined by the digital code
loaded into the controlling serial input register. The resistance
between the wiper and either endpoint of the fixed resistor
varies linearly with respect to the digital code transferred into
the VR latch. Each variable resistor offers a completely
programmable value of resistance between the A terminal and
the wiper or the B terminal and the wiper. The fixed A-to-B
terminal resistance of 1 kΩ, 10 kΩ, 50 kΩ, or 100 kΩ has a ±1%
channel-to-channel matching tolerance with a nominal
temperature coefficient of 500 ppm/°C. A unique switching
circuit minimizes the high glitch inherent in traditional
switched resistor designs, avoiding any make-before-break
or break-before-make operation.
Figure 2. RWA and RWB vs. Code
(continued on Page 3)
1
The terms digital potentiometer, VR, and RDAC are used interchangeably.
Rev. E
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
© 2010 Analog Devices, Inc. All rights reserved.
