The MCP4131-503E/P from Microchip Technology is a single-channel digital potentiometer configured as a linear-taper potentiometer with 50 kOhm end-to-end resistance and 129 tap positions. Communication is over the SPI interface, and the wiper setting is held in volatile memory — on power-up the wiper defaults to the mid-scale position, which must be factored into the system initialization sequence. The 129 taps resolve the 50 kOhm range into steps of approximately 390.6 Ohm per tap, with a typical wiper resistance of 75 Ohm that adds in series at the extremes.
Supply voltage, temperature range, and package
The typical temperature coefficient of 150 ppm/°C means the resistance drifts about 7.5 Ohm per °C at the 50 kOhm full-scale setting — acceptable for bias and adjustment circuits but worth derating in precision divider applications.
Tolerance and wiper resistance — real-world margin
End-to-end resistance tolerance is ±20 %, so a 50 kOhm nominal part can measure between 40 kOhm and 60 kOhm at the factory. The wiper resistance is typically 75 Ohm but varies with supply voltage and temperature. For a calibration trim where the absolute resistance matters, the ±20 % tolerance means the system must accommodate the full spread or include a calibration step to measure the actual value.
Lifecycle and compliance
The part is RoHS3 compliant, which satisfies EU and most global environmental requirements for new builds.