NXP Semiconductors FRDMKL25-A8491

Overview

FRDMKL25-A8491 from NXP Semiconductors is a FRDM-KL25Z-based evaluation board designed to host and demonstrate the MMA8491Q 3-axis digital accelerometer. It provides I²C interface, push-pull tilt outputs (Xout/Yout/Zout), ±8 g full-scale range, 14-bit resolution with 1 mg/LSB sensitivity, and supports both 45° tilt detection and raw acceleration data acquisition. The board enables rapid prototyping for tamper-detect and orientation-sensing applications in smart grid and white goods systems.

For engineers reviewing the FRDMKL25-A8491 datasheet, FRDMKL25-A8491 pinout, FRDMKL25-A8491 application, or FRDMKL25-A8491 equivalent, this page delivers verified mechanical integration details, confirmed I²C address (0x55), validated power sequencing (EN pulse timing, Byp capacitor requirement), tilt threshold (0.688 g / 43.5°), and functional mode behavior (ACTIVE/STANDBY/SHUTDOWN) - all directly extracted from NXP's official MMA8491Q documentation and FRDM-KL25Z platform specifications.

Technical Context

The FRDMKL25-A8491 integrates the MMA8491Q accelerometer onto the Freedom KL25Z development platform, leveraging the MKL25Z128VLK4 MCU's I²C peripheral and GPIOs to interface with Xout/Yout/Zout and EN. The board implements the required 0.1 μF bypass capacitor on the Byp pin and uses pull-up resistors on SDA/SCL per I²C Fast Mode (400 kHz) compliance.

It supports dual operational modes: tilt-sensing mode (push-pull logic outputs active at |a| > 0.688 g) and digital-output mode (14-bit I²C-accessible data). Power management follows the MMA8491Q's enable-driven sequencing - EN pulsed high for one-shot sampling, with turn-on time ≤ 720 μs and shutdown current ≤ 68 nA.

Key Specifications

Availability

FRDMKL25-A8491 is available at Aetrix Electronics and suitable for smart grid tamper detection, anti-theft orientation monitoring, white goods tilt sensing, and remote control gesture recognition requiring stable component supply and rapid evaluation capability.

Supply support for FRDMKL25-A8491 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

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with core expertise in sensor fusion, microcontrollers, and embedded security.

The FRDMKL25-A8491 belongs to NXP's Freedom Development Platform family, engineered to accelerate prototyping of low-power motion-sensing applications using integrated accelerometers like the MMA8491Q alongside Kinetis L-series MCUs.

FAQ

What is the primary function of the FRDMKL25-A8491 evaluation board?

The FRDMKL25-A8491 evaluation board hosts the MMA8491Q 3-axis accelerometer on the FRDM-KL25Z platform to demonstrate both 45° tilt detection (via Xout/Yout/Zout push-pull outputs) and high-resolution digital acceleration measurement (via I²C). It provides validated hardware layout, power conditioning, and firmware-ready interfaces - enabling immediate testing of tamper-detect logic, orientation state machines, and low-power wake-up triggers without custom PCB design. The FRDMKL25-A8491 is not a standalone sensor but a fully integrated evaluation system.

Does the FRDMKL25-A8491 support direct connection to a host MCU without level-shifting?

Yes. The FRDMKL25-A8491 operates at 3.3 V and uses push-pull outputs for Xout/Yout/Zout and open-drain I²C lines (SDA/SCL) with onboard 4.7 kΩ pull-ups - matching the KL25Z MCU's I/O voltage and drive strength. No level-shifting is required when interfacing with the onboard MKL25Z or other 3.3 V microcontrollers. The FRDMKL25-A8491's EN pin accepts 1.95–3.6 V logic, ensuring compatibility with standard GPIOs.

What is the exact tilt detection threshold implemented on the FRDMKL25-A8491?

The FRDMKL25-A8491 implements the MMA8491Q's factory-calibrated tilt threshold of 0.688 g (typical), corresponding to ±43.5° from horizontal across all axes. This value is specified over –40°C to +85°C (0.577–0.784 g) and is independent of I²C communication - activated solely by the EN pulse. The FRDMKL25-A8491 preserves this hardwired analog comparator behavior, delivering deterministic HIGH/LOW transitions on Xout/Yout/Zout without firmware intervention.

How does power management work on the FRDMKL25-A8491?

Power management on the FRDMKL25-A8491 follows the MMA8491Q's enable-driven architecture: the KL25Z drives the EN pin to initiate one-shot sampling. When EN is low, the MMA8491Q draws ≤ 68 nA (shutdown mode); when pulsed high, it enters ACTIVE mode (≤ 720 μs turn-on), then auto-transitions to STANDBY for data readout. The FRDMKL25-A8491 includes the mandatory 0.1 μF capacitor on the Byp pin to stabilize the internal 1.8 V regulator - critical for achieving sub-μA quiescent current.

Can the FRDMKL25-A8491 be used for continuous acceleration data logging?

No - the FRDMKL25-A8491 is optimized for event-triggered, low-duty-cycle operation. The MMA8491Q does not support continuous streaming; it acquires one sample per EN pulse and holds results in registers until read via I²C. For sustained data capture, external firmware must repeatedly assert EN and poll STATUS (0x00) before reading OUT_X_MSB (0x01) through OUT_Z_LSB (0x06). The FRDMKL25-A8491 provides no onboard memory or real-time clock - making it unsuitable for autonomous long-duration logging without host MCU coordination.