AD5200/AD5201,pdf datasheet (D

The AD5200 and AD5201 are programmable resistor devices,
with 256 positions and 33 positions respectively, that can be digitally
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 μSOIC-10
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