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NXP Semiconductors MMA6821BKWR2
- Part No.:
- MMA6821BKWR2
- Manufacturer:
- NXP Semiconductors
- Category:
- Accelerometers
- Package:
- 16-QFN Exposed Pad
- Datasheet:
-
MMA6821BKWR2.pdf
- Description:
- ACCELEROMETER 120G/25G SPI 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,972
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Product details
Overview
MMA6821BKWR2 from NXP Semiconductors (formerly Freescale) is a dual-axis SPI inertial sensor designed for automotive airbag deployment systems. It delivers ±120g X-axis and ±25g Y-axis full-scale acceleration measurement, 10-bit signed/unsigned SPI output, and programmable low-pass filtering with 12 selectable cutoff frequencies from 50 Hz to 1000 Hz.
For engineers reviewing the MMA6821BKWR2 datasheet, MMA6821BKWR2 pinout, MMA6821BKWR2 application, or MMA6821BKWR2 equivalent, this page provides verified technical context, AEC-Q100 qualified specifications, automotive-grade arming logic, offset cancellation capability, and real-world airbag system integration guidance.
Technical Context
The MMA6821BKWR2 integrates two over-damped lateral g-cells with independent analog signal chains, each feeding a ΣΔ converter followed by SINC-based digital filtering and IIR compensation. Its internal 8 MHz oscillator is divided to generate precise timing for sampling, interpolation, and low-pass filter configuration.
It supports configurable arming outputs (ARM_X/ARM_Y) with open-drain active-high/low modes or PCM-encoded acceleration data output, and includes factory-trimmed OTP registers for device-specific calibration, serial number, and part identification - all validated under AEC-Q100 Rev. G for automotive safety-critical operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| X-Axis Range | ±120g - enables detection of high-deceleration frontal crash events in passenger vehicles and light trucks |
| Y-Axis Range | ±25g - optimized for side-impact sensing with higher resolution at lower acceleration levels |
| Digital Output | 10-bit signed or unsigned SPI - provides 1024-level resolution with configurable zero-g reference (0 or 512 LSB) |
| Low-Pass Filter | 12 options (50–1000 Hz) - allows tuning bandwidth to match vehicle structural response and reduce noise without compromising crash detection speed |
| Supply Voltage | 3.3 V or 5.0 V single supply - supports legacy 5V automotive microcontrollers and modern 3.3V domains without level-shifting |
| AEC-Q100 Grade | Qualified to Rev. G - certified for automotive safety applications including airbag control units requiring ASIL-B compliance support |
| Offset Cancellation | 6.29 s averaging period, <0.25 LSB/s slew rate - enables long-term drift correction while maintaining fast fault response during crash events |
Pinout & Package
Pb-free 16-pin QFN package (6 mm × 6 mm, Case 2086-01), thermally enhanced with exposed die attach pad connected internally to VSS.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREGA | Analog supply input | Provides regulated 2.5 V to analog circuitry; requires 1 μF ceramic capacitor to VSSA for stability |
| VSS / VSSA | Digital and analog ground | Separate ground returns prevent digital switching noise from corrupting sensitive analog acceleration measurements |
| ARM_X / ARM_Y | Configurable arming output | Open-drain output that asserts within 1.05 μs when acceleration exceeds programmable thresholds - directly drives airbag squib enable logic |
| MISO / MOSI / SCLK / CS | SPI interface | Full-duplex 4-wire SPI compliant with standard microcontroller peripherals; supports up to 8 MHz clock (tSCLK ≥ 120 ns) |
| TEST/VPP | Factory programming voltage | Must be tied to VSS in application; not user-accessible during normal operation |
Key Features
| Feature | Design Value |
|---|---|
| Independent axis arming | Each axis has dedicated programmable threshold, hysteresis, and averaging - enables asymmetric crash detection logic for front vs. side impact |
| Over-damped g-cell design | Natural frequency 10.8–15.9 kHz with damping ratio 2.46–9.36 - eliminates resonance-induced false triggers during high-frequency road vibration |
| Self-test capability | Two-level electrostatic self-test (ΔSTLow/ΔSTHI) with cross-axis monitoring - verifies sensor integrity before vehicle startup and during periodic diagnostics |
| Offset monitor circuit | Detects >±100 LSB offset deviation (412–612 LSB range) and flags via DEVSTAT register - ensures calibration validity across temperature and lifetime |
| Power supply monitoring | Dual undervoltage/overvoltage detection on VREG (2.10–2.85 V) and VREGA (2.20–2.85 V) with 20–110 mV hysteresis - prevents operation outside safe analog/digital bias ranges |
Applications
| Frontal Crash Detection | Side-Impact Sensing |
|---|---|
Use Scenario: High-speed frontal collision where vehicle deceleration exceeds 40g within 15 ms. IC Role / Device Role / Timing Role: Primary X-axis acceleration sensor providing real-time crash pulse data to airbag ECU for squib firing decision. Use Value: ±120g range captures full crash profile without saturation; 400 Hz LPF option preserves pulse fidelity while rejecting engine and suspension noise. | Use Scenario: T-bone impact causing lateral acceleration >15g within 10 ms. IC Role / Device Role / Timing Role: Dedicated Y-axis sensor triggering side airbag and curtain deployment independently of frontal sensors. Use Value: ±25g range delivers 0.024g/LSB resolution for precise low-g event discrimination; independent arming avoids false triggers from rollover or pothole shocks. |
| Occupant Position Detection | Pre-Crash System Input |
Use Scenario: Detecting rear-seat occupant presence and position via low-level seat vibration and tilt. IC Role / Device Role / Timing Role: Low-noise Y-axis channel used in conjunction with seat belt and weight sensors for occupant classification. Use Value: RMS noise ≤0.5 LSB (400 Hz LPF) enables reliable sub-0.1g motion detection; offset cancellation maintains accuracy over 10+ year vehicle life. | Use Scenario: Early crash prediction using pre-impact braking and steering transients. IC Role / Device Role / Timing Role: High-bandwidth X-axis data fed to predictive algorithm to estimate time-to-collision and pre-tension seatbelts. Use Value: 1000 Hz LPF mode supports 1 kHz sampling for transient capture; <187 μs g-cell delay ensures minimal latency in critical control loop. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-axis automotive accelerometer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMA6823BKWR2 | ±120g X-axis, ±60g Y-axis - higher Y-axis range reduces resolution (8.192 LSB/g vs. 20.479 LSB/g) | Preferred for symmetric side-impact systems requiring equal X/Y sensitivity; less suitable for asymmetric front/side architectures | Select when Y-axis crash energy expectation exceeds 25g and system tolerates coarser Y-axis quantization |
| ADXL312WBRMZ-RL | 3-axis, 13-bit output, I²C/SPI, ±1.5g to ±12g range - no AEC-Q100 qualification, lower g-range, different interface timing | Targeted at non-safety industrial or consumer motion sensing; lacks automotive reliability validation and arming outputs | Only consider for non-safety prototyping or secondary sensing; not acceptable for airbag deployment path |
Compared with MMA6821BKWR2, MMA6823BKWR2 offers balanced dual-axis range but sacrifices Y-axis resolution needed for precise side-impact discrimination, while ADXL312WBRMZ-RL lacks AEC-Q100 certification, arming functionality, and required g-range - making MMA6821BKWR2 uniquely suited for primary airbag sensing in production vehicles.
Availability
MMA6821BKWR2 is available at Aetrix Electronics and suitable for automotive airbag control units, occupant classification systems, and pre-crash safety modules requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for MMA6821BKWR2 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 focused on secure connectivity solutions for automotive, industrial, and IoT applications.
The MMA68xx family was developed specifically for automotive safety systems, with emphasis on functional safety, crash pulse fidelity, and robustness against electromagnetic interference and mechanical shock in harsh vehicle environments.
FAQ
What is the full-scale acceleration range of the MMA6821BKWR2 on each axis?
The MMA6821BKWR2 has an X-axis full-scale range of ±120g and a Y-axis full-scale range of ±25g. These values are fixed per the device variant and confirmed in the ordering information table of the Freescale MMA68xx datasheet Rev. 5. This asymmetric range supports differentiated crash detection requirements: high-g frontal impact on X and precision low-g side impact on Y. The MMA6821BKWR2 does not support reconfiguration of these ranges via software or external components.
Does the MMA6821BKWR2 support both signed and unsigned SPI output formats?
Yes, the MMA6821BKWR2 supports both 10-bit signed and unsigned SPI output formats. The format is selected by the SD bit (bit 3) in the DEVCFG register: when SD = 1, output is unsigned with 0g represented by 512 LSB; when SD = 0, output is signed with 0g at 0 LSB. This flexibility allows direct integration with microcontrollers expecting either format without external translation logic. The MMA6821BKWR2 implements this behavior per Section 3.1.6.3 of the datasheet.
How is the arming function implemented on the MMA6821BKWR2?
The MMA6821BKWR2 implements arming via dedicated ARM_X and ARM_Y pins, configurable through the DEVCFG and ARMCFGX/Y registers. Each pin can operate in open-drain active-low/high mode or as a PCM-encoded acceleration output. Arming activation time is ≤1.05 μs (typical) with 200 µA load, enabling deterministic squib enable timing. The MMA6821BKWR2 supports moving-average and count-based arming algorithms with programmable thresholds and hysteresis - all validated for AEC-Q100 automotive safety use.
Is the MMA6821BKWR2 qualified to AEC-Q100 standards?
Yes, the MMA6821BKWR2 is qualified to AEC-Q100 Revision G, as explicitly stated in the "Referenced Documents" section of the Freescale MMA68xx datasheet Rev. 5. This qualification covers stress testing for temperature cycling, humidity, mechanical shock, and ESD (±2000 V HBM), confirming suitability for automotive safety-critical applications including airbag control units. The MMA6821BKWR2's qualification status is part number-specific and documented in Freescale's official release.
What package type and dimensions does the MMA6821BKWR2 use?
The MMA6821BKWR2 uses a Pb-free 16-pin QFN package measuring 6 mm × 6 mm (Case 2086-01), with an exposed die attach pad internally connected to VSS. Pin layout and thermal characteristics are defined in Figures 4 and Table 2 of the MMA68xx datasheet Rev. 5. This package supports automated SMT assembly and provides low thermal resistance (θJC = 2.5 °C/W) for stable operation in under-hood environments. The MMA6821BKWR2's footprint is identical across the MMA68xx family.
MMA6821BKWR2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 16-QFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Digital
- Axis:
- X, Y
- Acceleration Range:
- ±120g, ±25g
- Sensitivity (LSB/g):
- 4.096 (X), 20.479 (Y)
- Sensitivity (mV/g):
- -
- Bandwidth:
- -
- Output Type:
- SPI
- Voltage - Supply:
- 3.135V ~ 5.25V
- Features:
- -
- Operating Temperature:
- -40°C ~ 105°C
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (6x6)
MMA6821BKWR2 FAQ
1.How can I place an order for MMA6821BKWR2 through Aetrix?
Please submit a Request for Quotation (RFQ) for MMA6821BKWR2 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MMA6821BKWR2 reliable?
The price and inventory of MMA6821BKWR2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMA6821BKWR2 is usually 5 days.
3.What payment methods are accepted for MMA6821BKWR2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMA6821BKWR2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMA6821BKWR2?
MMA6821BKWR2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMA6821BKWR2 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MMA6821BKWR2?
For technical support, including MMA6821BKWR2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMA6821BKWR2 requirements.
6.How does Aetrix verify that MMA6821BKWR2 is sourced from the original manufacturer or authorized distributors?
All MMA6821BKWR2 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MMA6821BKWR2 meets industry standards.
7.What is the process for return or replacement of MMA6821BKWR2?
All MMA6821BKWR2 units undergo pre-shipment inspection (PSI). If there is an issue with MMA6821BKWR2, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MMA6821BKWR2 part is unused and in its original packaging.
Return procedure for MMA6821BKWR2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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