Microchip MCP4021T-103E/MC Digital Potentiometer: Features, Application Circuit, and Configuration Guide

The Microchip MCP4021T-103E/MC is a 7-bit (128 wiper steps) non-volatile digital potentiometer designed to provide a compact and reliable digital alternative to traditional mechanical potentiometers and trimmers. As part of the MCP4021 family, this device integrates a resistor array and wiper switching circuitry, controlled via a simple up/down (U/D) interface. Its non-volatile memory ensures that the wiper position is retained even when power is removed, making it ideal for applications requiring stable, repeatable settings after power cycles.

Key Features

The MCP4021T-103E/MC offers several standout characteristics. It features a 10kΩ end-to-end resistance with 128 linearly spaced taps. The device operates from a wide voltage range of 2.7V to 5.5V, making it suitable for both 3.3V and 5V systems. Its low wiper resistance (typically 52Ω) and low temperature coefficient ensure stable performance across varying conditions. Communication is handled through a simple two-wire incremental up/down (U/D) interface, minimizing the number of required MCU GPIO pins. Furthermore, the integrated non-volatile memory (EEPROM) saves the wiper position at shutdown, enabling immediate recall of the last setting at power-up.

Application Circuit

A typical application circuit for the MCP4021T-103E/MC is straightforward. The device is configured as a variable resistor by leaving terminal A (V_A) unconnected or tied to the wiper (V_W), and using terminal B (V_B) as the other endpoint. The U/D and CS (Chip Select) pins are controlled by a microcontroller. To increase the wiper position (and thus the resistance between V_W and V_B), the U/D pin is held high and the CS pin is toggled low-high. To decrease the resistance, U/D is held low during the CS toggle. A simple push-button interface can also be implemented for manual control without a microcontroller. Decoupling capacitors (e.g., 0.1µF) should be placed close to the VDD and VSS pins for stable operation.

Configuration Guide

Configuring the MCP4021T-103E/MC is primarily about controlling its two digital inputs: Chip Select (CS) and Up/Down (U/D). The wiper position is incremented or decremented by one step each time CS is brought high while the U/D pin is in a stable state. Holding U/D high during the CS low-to-high transition increases the resistance. Conversely, holding U/D low decreases it. The non-volatile memory is updated automatically whenever the wiper setting is changed, ensuring the value is stored for the next power cycle. For applications requiring a specific startup value, the wiper can be preset by cycling power after setting the desired value.

ICGOOFind Summary

ICGOOFind: The MCP4021T-103E/MC digital potentiometer is a highly integrated, easy-to-use solution for digital resistance control. Its non-volatile memory, simple two-wire interface, and compact package make it an excellent choice for replacing mechanical pots in applications like gain adjustment, sensor calibration, and programmable voltage references in portable devices, automotive systems, and industrial controls.

Keywords: Digital Potentiometer, Non-Volatile Memory, Up/Down Interface, 10kΩ Resistance, Wiper Control.