NXP Semiconductors DEMOMPR031

Overview

DEMOMPR031 from Freescale Semiconductor is a proximity capacitive touch sensor controller IC optimized for managing up to three electrode inputs via I²C interface, delivering 6 µA supply current with 32 ms response time and active-low open-drain IRQ output, used in mobile phone front-panel touch interfaces and lighting control panels.

For engineers reviewing the DEMOMPR031 datasheet, DEMOMPR031 pinout, DEMOMPR031 application, or DEMOMPR031 equivalent, key selection considerations include its 2×2 mm µDFN-8 package, 1.71–2.75 V operation, 0x4A I²C address, 3-electrode support with IRQ/ELE2 multiplexing, and integrated baseline calibration eliminating host-side capacitance compensation.

Technical Context

The MPR03X architecture integrates a 10-bit ADC, three-stage digital filtering (sample, average, debounce), and self-calibrating baseline tracking per electrode. It supports two operational modes: Run1 (independent electrode monitoring) and Run2 (area-detection mode with internally connected electrodes).

Its analog front end uses programmable charge current (16 µA default), configurable charge time (0.5 µs default), and REXT-based reference (75 kΩ ±1% to VSS). The IRQ pin functions as either interrupt output or third electrode input depending on Electrode Configuration Register (0x44) settings.

Key Specifications

Pinout & Package

Package: 2 mm × 2 mm × 0.65 mm 8-pin µDFN (Case 1944), exposed thermal pad (not electrically connected), moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar capacitive touch sensor controller applications.

Compared with MPR032EPR2, DEMOMPR031 offers identical performance in a single-device configuration with fixed 0x4A addressing; compared with AT42QT1070-MAHR, it delivers lower supply voltage operation, smaller footprint, and simpler external component count at the cost of channel count scalability.

Availability

DEMOMPR031 is available at Aetrix Electronics and suitable for mobile phone UIs, lighting control panels, PC peripherals, and remote controls requiring stable component supply across long-lifecycle consumer electronics programs.

Supply support for DEMOMPR031 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) is a fabless semiconductor company specializing in microcontrollers, sensors, and analog interface ICs for automotive, industrial, and consumer applications.

The MPR03X product line was designed specifically for ultra-low-power capacitive touch sensing in space-constrained portable devices, emphasizing minimal external components, adaptive baseline calibration, and I²C simplicity.

FAQ

What is the I²C address of the DEMOMPR031 and how does it differ from MPR032?

The DEMOMPR031 uses a fixed 7-bit I²C slave address of 0x4A. This differs from the MPR032, which uses 0x4B. Both share identical pinout, electrical specifications, and register map-enabling dual-device configurations on the same I²C bus for up to six total electrodes without conflict. The DEMOMPR031 address is hardwired and not software-configurable.

Can the DEMOMPR031 support three electrodes while maintaining interrupt functionality?

No-the DEMOMPR031 cannot simultaneously support three electrodes and use the IRQ output. Pin 8 (IRQ/ELE2) is multiplexed: when configured for three-electrode operation (ELE0, ELE1, ELE2), the pin serves exclusively as ELE2 input and IRQ is disabled. To retain IRQ, only two electrodes (ELE0 and ELE1) may be enabled, with pin 8 functioning as the active-low open-drain interrupt output.

What external components are mandatory for DEMOMPR031 operation?

The DEMOMPR031 requires exactly three external components: a 75 kΩ ±1% resistor from pin 5 (REXT) to VSS, a 10 µF bypass capacitor between pins 4 (VDD) and 3 (VSS), and a 4.7 kΩ pull-up resistor on pin 8 (IRQ/ELE2) if used as an interrupt output. No additional timing or filtering components are needed-the DEMOMPR031 integrates all signal conditioning internally.

How does the DEMOMPR031 handle environmental drift such as temperature or humidity changes?

The DEMOMPR031 implements continuous self-calibration of each electrode's baseline capacitance using a third-level digital filter. This baseline value is updated in real time and stored in dedicated registers (0x1A–0x1C), enabling robust touch detection across −40°C to +85°C and varying humidity without host intervention. The system automatically compensates for slow drift while preserving fast response to intentional touch events.

What is the minimum detectable capacitance change supported by the DEMOMPR031?

At nominal conditions (VDD = 1.8 V, 16 µA charge current, 0.5 µs charge time), the DEMOMPR031 achieves ~0.02 pF sensitivity per ADC count near mid-range (512 counts), corresponding to sub-0.1 pF resolution for small electrodes (~21 pF). Sensitivity improves at lower capacitance values due to the inverse relationship between measured capacitance and ADC output-making it ideal for compact PCB trace electrodes.