WMS7170 / 7171

        The WMS7170 / 7171 is a single channel 100-tap non-volatile linear digital potentiometer available in 10K, 50K and 100K resistance. The device consists of Up/Down serial interface, tap register,decoder, resistor array, wiper switches, NV memory and control logics.The WMS7170 device can be configured as a two-terminal variable resistor or a three-terminal voltage divider without an output buffer, but the WMS7171 device, which has a built-in output buffer, can only be configured as a three-terminal voltage divider. Both devices can be used in a wide variety of applications.The output of the potentiometer is determined by its wiper position, which varies linearly between its end terminals, RA/VA and RB/VB. The wiper position, Rw/Vw, is controlled by Up/Down serial interface (CS, INC and U/D) through the Tap Register (TR). In addition, the wiper position can also be stored into a non-volatile memory location (NVMEM0), which is then automatically recalled upon power up.
       The WMS7170 / 7171 has 12 features.The first one is Drop-in replacement for many popular parts.The second one is Single linear-taper channel.The third one is 100 taps.The fourth one is 10K, 50K and 100K end-to-end resistance.The fifth one is VSS to VDD terminal voltages.The sixth one is Automatic recall of wiper position when power-on.The seventh one is Potentiometer control through Up/Down (3-wire) serial interface.The eighth one is Endurance 100,000 cycles.The ninth one is Data retention 100 years.The tenth one is Package options:8-pin PDIP, SOIC or MSOP.The eleventh one is Industrial temperature range: -40° to 85°C.The twelfth one is Single supply operation : 2.7V to 5.5V.
      The WMS7170 / 7171 device can operate as either a two-terminal variable resistor or a three-terminal voltage divider without an output buffer. However, the WMS7171 can only operate in a three-terminal voltage divider with an output buffer.In the rheostat mode, the WMS7170 can be configured as a two-terminal resistive element, where one terminal is connected to one end of the resistor (RA or RB) and the other terminal is the wiper (RW).The moving direction of the wiper depends upon the setting of U/Dcontrol signal. When the U/D is set to Up, then the wiper moves towards RA. Conversely, when the U/D is set to Down, then the wiper moves towards RB. The wiper movement to either direction is controlled by toggling the INC signal from HIGH to LOW.This configuration controls the resistance between the wiper and either end. The wiper resistance of the WMS7170 / 7171 can be adjusted by either changing the wiper position or loading a stored wiper position value from NVMEM0 upon power up.