The MCP41XXX and MCP42XXX devices are 256- position， digital potentiometers available in 10 k?， 50 k? and 100 k? resistance versions. The MCP41XXX is a single-channel device and is offered in an 8-pin PDIP or SOIC package. The MCP42XXX contains two independent channels in a 14-pin PDIP， SOIC or TSSOP package. The wiper position of the MCP41XXX/42XXX varies linearly and is controlled via an industry-standard SPI interface. The devices consume 《1 μA during static operation. A software shutdown feature is provided that disconnects the “A” terminal from the resistor stack and simultaneously connects the wiper to the “B” terminal. In addition， the dual MCP42XXX has a SHDN pin that performs the same function in hardware. During shutdown mode， the contents of the wiper register can be changed and the potentiometer returns from shutdown to the new value. The wiper is reset to the mid-scale position （80h） upon power-up. The RS （reset） pin implements a hardware reset and also returns the wiper to mid-scale. The MCP42XXX SPI interface includes both the SI and SO pins， allowing daisy-chaining of multiple devices. Channel-to-channel resistance matching on the MCP42XXX varies by less than 1%. These devices operate from a single 2.7 - 5.5V supply and are specified over the extended and industrial temperature ranges.