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a
AD5200/AD5201
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FUNCTIONAL BLOCK DIAGRAM
SER
REG
PWR-ON
PRESET
A
W
B
RDAC
REG
Dx
8/6
CS
CLK
SDI
AD5200/AD5201
V
SS
V
DD
GND
SHDN
256-Position and 33-Position
Digital Potentiometers
FEATURES
AD5200—256-Position
AD5201—33-Position
10 k, 50 k
3-Wire SPI-Compatible Serial Data Input
Single Supply 2.7 V to 5.5 V or
Dual Supply 2.7 V for AC or Bipolar Operations
Internal 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
GENERAL DESCRIPTION
The AD5200 and AD5201 are programmable resistor devices,
with 256 positions and 33 positions respectively, that can be digi-
tally controlled through a 3-wire SPI serial interface. The terms
programmable resistor, variable resistor (VR), and RDAC are
commonly used interchangeably to refer to digital potentiometers.
These devices perform the same electronic adjustment function
as a potentiometer or variable resistor. Both AD5200/AD5201
contain a single variable resistor in the compact
package. Each device contains a fixed wiper resistance at the
wiper contact that taps the programmable resistance at a point
determined by a digital code. The code is loaded in the serial
input register. The resistance between the wiper and either end
point of the programmable 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 10 kΩ or 50 kΩ
has a nominal temperature coefficient of 500 ppm/°C. The VR
has a VR latch that holds its programmed resistance value. The
VR latch is updated from an SPI-compatible serial-to-parallel
shift register that is loaded from a standard 3-wire serial-input
digital interface. Eight data bits for the AD5200 and six data
bits for the AD5201 make up the data word that is clocked into
the serial input register. The internal preset forces the wiper to
the midscale position by loading 80
H
and 10
H
into AD5200 and
AD5201 VR latches respectively. The SHDN pin forces the
resistor to an end-to-end open-circuit condition on the A terminal
and shorts the wiper to the B terminal, achieving a microwatt
power shutdown state. When SHDN is returned to logic high,
the previous latch setting puts the wiper in the same resistance
setting prior to shutdown. The digital interface is still active dur-
ing shutdown so that code changes can be made that will produce
a new wiper position when the device is returned from shutdown.
All parts are guaranteed to operate over the extended industrial
temperature range of –40°C to +85°C.
