129-tap digital rheostat with non-volatile wiper storage
The MCP4142-502E/P is a single-channel digital potentiometer configured as a rheostat, offering 129 tap points across a 5 kOhm resistance range with a linear taper. The SPI interface writes the wiper position, and the integrated non-volatile memory (WiperLock technology) retains that setting at power-off — no firmware recall routine needed on start-up.
SPI bus timing and wiper resistance budget
The 129-tap resolution gives approximately 39 ohms per step on the 5 kOhm element — enough granularity for fine adjustment of bias voltages, comparator thresholds, or sensor offset trim. The wiper resistance is 75 ohms typical, which sets the minimum end-to-end resistance when the wiper is at the bottom of the string; budget this into the divider ratio if the application needs a true zero-ohm endpoint. Tolerance is ±20% on the total resistance element, so the absolute step size varies by part. For ratiometric applications (voltage divider) the step accuracy is better than the absolute tolerance because the resistor string is monolithic. The linear taper means each tap step is an equal resistance increment — no pseudo-log compression at the low end. The 8-DIP package (0.300" body, 7.62 mm pitch) is through-hole, which simplifies breadboarding and hand-assembly but occupies more board area than a surface-mount alternative. The supplier device package is 8-PDIP; the lead pitch is compatible with standard 0.1-inch prototyping grids.