NXP Semiconductors MMA1251KEG

Overview

MMA1251KEG from Freescale Semiconductor is a low-g, silicon capacitive micromachined accelerometer with integrated signal conditioning, 2nd-order Bessel low-pass filter, and factory-calibrated self-test. It delivers ratiometric analog output (±1g range, 80 mV/g sensitivity), operates from 4.75–5.25 V, draws 2.1 mA typical, and is qualified to AEC-Q100 Grade 2 (–40°C to +105°C) for automotive and industrial vibration monitoring.

For engineers reviewing the MMA1251KEG datasheet, MMA1251KEG pinout, MMA1251KEG application, or MMA1251KEG equivalent, this page provides verified technical context, SOIC-16 pin mapping, real-world use scenarios in hard drive protection and appliance control, and validated alternative parts with documented functional differences.

Technical Context

The MMA1251KEG implements a surface-micromachined polysilicon g-cell with back-to-back capacitors, read via switched-capacitor CMOS ASIC. Its on-chip 2-pole Bessel filter (f_−3dB = 400 Hz typ.) ensures linear phase response and pulse shape integrity without external components.

Self-test is activated by a logic-high ST input, applying electrostatic force to deflect the movable plate; the resulting ΔV_ST = 0.25 V/V output verifies mechanical and electrical integrity. Fault detection latches STATUS high on EPROM parity error, clock failure, or low-voltage condition-resettable via ST pulse.

Key Specifications

Pinout & Package

Package: 16-lead SOIC (Case 475-01), Pb-free, hermetically sealed at wafer level for high reliability in harsh environments.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-g analog accelerometer applications.

Compared with ADXL326BCPZ and MMA8451Q, the MMA1251KEG uniquely combines analog output, factory-calibrated self-test, STATUS fault latch, and AEC-Q100 qualification in a single SOIC-16 package - making it optimal for safety-aware analog-signal-path designs where deterministic hardware-level diagnostics are required.

Availability

MMA1251KEG is available at Aetrix Electronics and suitable for computer hard drive protection, appliance control, vibration monitoring and recording, and computer mouse and joystick applications requiring stable component supply across automotive and industrial production lifecycles.

Supply support for MMA1251KEG 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) was a leading designer of embedded processors, sensors, and analog ICs, with core expertise in automotive, industrial, and consumer microelectromechanical systems.

The MMA1251KEG belongs to Freescale's legacy MMA series of silicon capacitive accelerometers, engineered specifically for high-reliability, low-g analog sensing in safety-critical and maintenance-sensitive applications such as airbag readiness checks and predictive equipment health monitoring.

FAQ

What is the operating supply voltage range for the MMA1251KEG?

The MMA1251KEG operates from 4.75 V to 5.25 V. Within this range, the device functions as a fully calibrated linear accelerometer. Operation outside these limits may yield linear output but voids factory calibration guarantees. The datasheet specifies 2.1 mA typical supply current at 5.0 V and 25°C, and the VDD pin requires a 0.1 μF ceramic decoupling capacitor placed close to the package per recommended PCB layout.

Does the MMA1251KEG provide built-in self-test functionality, and how is it activated?

Yes, the MMA1251KEG includes a calibrated self-test feature. It is activated by applying a logic-high signal to the ST pin (Pin 8). This applies electrostatic force to the movable g-cell plate, producing a predictable output shift of 0.25 V/V (e.g., ~1.25 V at 5 V supply). The STATUS pin reflects self-test activity and faults, and the self-test can be triggered at any time - before or after installation - to verify mechanical and electronic integrity of the MMA1251KEG.

What does the STATUS pin indicate, and how is it reset?

The STATUS pin on the MMA1251KEG is an open-drain output that latches high upon occurrence of EPROM parity error, internal clock frequency failure, or supply undervoltage. It also goes high during active self-test. To reset the latch, a rising edge ≥100 μs must be applied to the ST pin - unless the underlying fault persists. The STATUS pin is not valid immediately after power-up until at least one ST edge has occurred, ensuring reliable initialization sequencing for the MMA1251KEG.

Is the MMA1251KEG RoHS-compliant and qualified for automotive use?

Yes, the MMA1251KEG is RoHS-compliant and Pb-free, packaged in a 16-lead SOIC (Case 475-01). It is qualified to AEC-Q100 Grade 2, meaning it is tested and guaranteed to operate reliably from –40°C to +105°C - suitable for under-hood and other demanding automotive environments. Its wafer-level hermetic seal and 1500 g powered shock survivability further reinforce its suitability for automotive and industrial applications where long-term stability is critical for the MMA1251KEG.

What is the output configuration and noise performance of the MMA1251KEG?

The MMA1251KEG provides a ratiometric analog voltage output (VOUT, Pin 4) centered at VDD/2, spanning ±0.4 VDD for ±1g input. At 5.0 V supply, this yields 2.5 V ± 2.0 V output. Its RMS noise is 2.0 mV_rms over 0.1–1.0 kHz, corresponding to ~250 μg noise floor - ideal for precision low-g measurements. An external 1 kΩ + 0.1 μF RC filter is required on VOUT to suppress switched-capacitor clock noise, as specified in the MMA1251KEG datasheet.