AD5233

The AD5231/AD5232/AD5233 family provides a single- /dual-/quad-channel, digitally controlled variable resistor (VR) with resolutions of 1024/256/64 positions respectively. These devices perform the same electronic adjustment function as a potentiometer or variable resistor. The AD523X's versatile programming via a Micro Controller allows multiple modes of operation and adjustment.

In the direct program mode a predetermined setting of the RDAC register can be loaded directly from the micro controller. Another key mode of operation allows the RDAC register to be refreshed with the setting 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 the settings are saved in the EEMEM register these values will be transferred automatically to the RDAC register to set the wiper position at system power ON. Such operation is enabled by the internal preset strobe and the preset can also be accessed externally.

The basic mode of adjustment is the increment and decrement command controlling 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 terminals A-and-B. This linearly changes the wiper to B terminal resistance (RWB) by one position segment of the device's end-to-end resistance (RAB). For exponential/logarithmic changes in wiper setting, a left/right shift command adjusts levels in +/-6dB steps, which can be useful for sound and light alarm applications.