a
FEATURES
256 Position
Multiple Independently Programmable Channels
AD5204鈥?-Channel
AD5206鈥?-Channel
Potentiometer Replacement
10 k , 50 k , 100 k
3-Wire SPI-Compatible Serial Data Input
+2.7 V to +5.5 V Single Supply; 2.7 V Dual Supply
Operation
Power ON Midscale Preset
APPLICATIONS
Mechanical Potentiometer Replacement
Instrumentation: Gain, Offset Adjustment
Programmable Voltage-to-Current Conversion
Programmable Filters, Delays, Time Constants
Line Impedance Matching
CS
CLK
4-/6-Channel
Digital Potentiometers
AD5204/AD5206
FUNCTIONAL BLOCK DIAGRAMS
AD5204
EN
A2
A1
A0
D7
ADDR
DEC
D0
D7
RDAC
LATCH
#1
R
V
DD
A1
W1
B1
SDO
DO
SER
REG
D7
SDI
DI
D0
8
POWER-
ON
PRESET
RDAC
LATCH
#4
D0
R
A4
W4
B4
SHDN
V
SS
PR
GND
GENERAL DESCRIPTION
The AD5204/AD5206 provides four-/six-channel, 256 position
digitally-controlled Variable Resistor (VR) devices. These de-
vices perform the same electronic adjustment function as a
potentiometer or variable resistor. Each channel of the AD5204/
AD5206 contains a fixed resistor with a wiper contact that taps
the fixed resistor value at a point determined by a digital code
loaded into the SPI-compatible serial-input register. The resis-
tance between the wiper and either endpoint of the fixed resistor
varies linearly with respect to the digital code transferred into
the VR latch. The variable resistor offers a completely program-
mable 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 10 k鈩? 50 k鈩? or 100 k鈩?has a nominal tempera-
ture coefficient of 700 ppm/擄C.
Each VR has its own VR latch which holds its programmed
resistance value. These VR latches are updated from an internal
serial-to-parallel shift register that is loaded from a standard
3-wire serial-input digital interface. Eleven data bits make up
the data word clocked into the serial input register. The first
three bits are decoded to determine which VR latch will be
loaded with the last eight bits of the data word when the
CS
strobe is returned to logic high. A serial data output pin at
the opposite end of the serial register (AD5204 only) allows
simple daisy-chaining in multiple VR applications without
additional external decoding logic.
CS
CLK
EN
A2
A1
A0
D7
ADDR
DEC
D0
D7
AD5206
V
DD
A1
W1
RDAC
LATCH
#1
R
B1
SER
REG
D7
SDI
DI
D0
8
POWER-
ON
PRESET
D0
RDAC
LATCH
#6
R
V
SS
A6
W6
B6
GND
An optional reset (PR) pin forces all the AD5204 wipers to the
midscale position by loading 80
H
into the VR latch.
The AD5204/AD5206 is available in both surface mount
(SOL-24), TSSOP-24 and the 24-lead plastic DIP package. All
parts are guaranteed to operate over the extended industrial
temperature range of 鈥?0擄C to +85擄C. For additional single,
dual, and quad channel devices, see the AD8400/AD8402/
AD8403 products.
REV. 0
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.
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
漏 Analog Devices, Inc., 1999
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