AD5255

The AD5255 is a dual channel, digitally controlled variable resistor (VR) with resolutions of 1024 positions. This device
performs the same electronic adjustment function as a potentiometer or variable resistor. The AD5255's versatile programming via a Micro Controller allows multiple modes of operation and adjustment. The basic mode of adjustment is the increment and decrement from the present setting of the Wiper position setting (RDAC) register. An internal scratch pad RDAC register can be moved UP or DOWN, one step of the nominal terminal resistance between A-and-B. This linearly changes the wiper to B terminal resistance (R_WB) by one position segment of the device's end-to-end resistance (R_AB). For non-linear changes in wiper setting a left/right shift command adjusts levels in 6dB steps for sound and light alarm applications. In the direct program mode a predetermined setting of the RDAC register can be loaded directly from the micro controller. The third mode allows the RDAC register to be refreshed with the present nonvolatile data previously stored in the EEMEM register. When changes are made to the RDAC register to establish a new wiper position, the value of the setting can be saved into the EEMEM by executing an EEMEM save operation. Once settings are saved in the EEMEM register, these values will always be transferred to the wiper position (RDAC) register at system power ON by the internal preset strobe and it can be accessed externally as well.

The AD5255 is available in the thin TSSOP-16 package. All parts are guaranteed to operate over the extended industrial temperature range of -40°C to +85°C.