The AD5253/AD5254 are quad-channel， I2 C?， nonvolatile mem-ory， digitally controlled potentiometers with 64/256 positions， respectively. These devices perform the same electronic adjust-ment functions as mechanical potentiometers， trimmers， and variable resistors. The parts’ versatile programmability allows multiple modes of operation， including read/write access in the RDAC and EEMEM registers， increment/decrement of resistance， resistance changes in ±6 dB scales， wiper setting readback， and extra EEMEM for storing user-defined information， such as memory data for other components， look-up table， or system identification information.

　　The AD5253/AD5254 allow the host I2 C controllers to write any of the 64-/256-step wiper settings in the RDAC registers and store them in the EEMEM. Once the settings are stored， they are restored automatically to the RDAC registers at system power-on; the settings can also be restored dynamically