Freescale Semiconductor Application Note Document Number: AN4992 Rev 1.0, 12/2014 Upgrading from the MMA7330L to the FXLN83xxQ Contents 1 Introduction 1 Introduction................................................................1 The FXLN83xxQ accelerometers expand Freescale's portfolio, adding best-in-class analog performance. These accelerometers are designed to support analog capability for industrial, medical, and tamper-detection applications. Additionally, these accelerometers provide interface compatibility and simplicity for low-voltage microcontrollers (MCUs). The FXLN83xxQ accelerometers are designed specifically for the Industrial market and are, therefore, part of Freescale's Longevity Program. 2 Key Benefits of using FXLN83xxQ..........................2 3 Upgrade Guide...........................................................3 The FXLN83xL analog accelerometer replaces the previous generation MMA73xxL Analog 3-axis accelerometer. This document describes the necessary steps to transition from the MMA73xxL 3-axis Analog Accelerometer family to the new FXLN83xxQ 3-Axis Analog Industrial Accelerometer to bring best-in-class power consumption and bandwidth to your analog applications. © 2014 Freescale Semiconductor, Inc. Key Benefits of using FXLN83xxQ 2 Key Benefits of using FXLN83xxQ Improved battery life in portable applications by reducing overall power consumption: Specification MMA7330L FXNL83xxQ Units Current consumption 400 180 μA Supply voltage range 2.2 – 3.6 1.71 – 3.6 V MMA7330L FXNL83xxQ Units 400 XY 2700 XY 300 Z 600 Z ±12 ±16 g Sensitivity @ ±4 g 308 114.51 mV/g Noise Density 350 200 XY, 280 Z (130 XY, 200 Z) μg/√Hz MMA7330L FXNL83xxQ Units Output Impedance 32 10 kΩ Nonratiometric output No Yes VBYP No Yes Enhanced user experience through performance improvements: Specification Max Bandwidth Max g-Range Hz 1. Can be improved by connecting VBYP to the VRefHigh input of your ADC Enhanced analog output performance: Specification Additional features and performance improvements: Specification Package MMA7330L FXNL83xxQ Units 3 x 5 x 1, 14-Pin LGA 3 x 3 x 1, 12-pin QFN mm Output at 0 g 1.4 0.75 V Cross-Axis Sensitivity ±5 ±4.2 % –40 to 85 –40 to 105 °C Operating Temperature A major feature of the FXLN83xxQ is its nonratiometric output. This means that VDD fluctuations, within the VDD specification for the part, will not change the output offset voltage or sensitivity. Therefore, a noisy power supply will not cause noisy output, thus resulting in a cleaner system. An additional benefit of nonratiometric output is that, when powered by a battery, the device will not suffer from signal drop off when the battery voltage drops as the stored energy is consumed. Previously with the MMA7330L, and with many other analog accelerometers currently on the market, the sensor's output was ratiometric to VDD. This meant that the output of the sensor was proportional to VDD and as the supply voltage fluctuated so did the output of the sensor. Using a ratiometric part required the user to monitor VDD and perform additional calculations to Upgrading from the MMA7330L to the FXLN83xxQ, Rev 1.0, 12/2014 2 Freescale Semiconductor, Inc. Upgrade Guide compensate for fluctuations or changes, such as the previously mentioned battery drop off. With the FXLN83xxQ, such extra effort is a thing of the past as the VBYP output on the FXLN83xxQ can be used as the full scale range input to the system ADC to improve performance. In general, the 0 g output from any of the XYZ axes will be equal to 1/2 of the VBYP output. 3 Upgrade Guide Upgrading to the FXLN83xxQ requires changes to the PCB, including adapting the layout to accept a 3x3x1 12-pin QFN package, rerouting the existing traces, and adding a trace for the VBYP pin. NC NC 1 XOUT YOUT 13 Self Test 2 12 NC 3 11 NC 14 NC NC 12 BYP 1 g-Select ZOUT 4 10 VSS 5 9 NC VDD 6 8 NC 7 11 10 XOUT VDD 2 9 YOUT ST 3 8 ZOUT EN 4 7 GND 5 6 g-Select GND Sleep MMA7330L FXLN83xxQ Table 1. Pinout Comparison MMA7330L Pin Name 2 XOUT 3 YOUT 4 FXLN83xxQ Function Pin Name X axis output voltage 10 XOUT X axis output voltage Y axis output voltage 9 YOUT Y axis output voltage ZOUT Z axis output voltage 8 ZOUT Z axis output voltage 6 VDD Power Supply Voltage 2 VDD Supply voltage 1,8,9,11, 12,14 NC No internal connection, leave floating 11-12 NC No internal connection 10 g-Select Logic input pin to select g level 5 g-Select 13 Self-test Input pin to initiate Self Test 3 ST 5 VSS 6-7 GND 7 Sleep 4 EN Power enable pin, enabled when logic high 1 VBYP1 Internal voltage regulator output capacitor connection Connect to Ground Sleep mode pin, enabled when logic low Function g-Range selection pin. Logic low: High-g mode, Logic High: Low-g mode Self-test enable pin, enabled when logic high Connect to Ground 1. The VBYP output on the FXLN83xxQ can be used as the full scale range input to an ADC to improve performance. The benefits of using this output are described in the section, Key Benefits of using FXLN83xxQ. Upgrading from the MMA7330L to the FXLN83xxQ, Rev 1.0, 12/2014 Freescale Semiconductor, Inc. 3 Upgrade Guide 3.1 Hardware Setup Based on Table 1, most of the traces will have to be rerouted to replace the MMA7330L with the FXLN83xxQ. The following should be considered when redesigning a PCB originally built for the MMA7330L: • The pin used for Sleep in the MMA7330L will be named EN and is enabled when logic high (connected to VDD). • The pin named VSS will be named GND and will continue to be connected to ground. • The addition of the VBYP pin will require a new trace. The single 0.1 µF capacitor between VDD and VSS/GND should be replaced with a 1.0 µF and a 0.1 µF (each with their own trace from Vdd to GND). 3.2 Capacitor Changes The capacitors on the XOUT, YOUT, and ZOUT branches are different on the FXLN83xxQ than on the MMA7330L. Use capacitors as recommended in Table 2. Table 2. Recommended Minimum Capacitance Specifications Part Number Bandwidth C4 (pF) C5 (pF) C6 (pF) Low 9100 9100 9100 FXLN8362Q Low 9100 9100 9100 FXLN8371Q High 8200 3300 3300 FXLN8372Q High 8200 3300 3300 FXLN8361Q XOUT C6 XOUT YOUT ZOUT GND 10 9 YOUT 8 7 C5 ZOUT C4 Upgrading from the MMA7330L to the FXLN83xxQ, Rev 1.0, 12/2014 4 Freescale Semiconductor, Inc. How to Reach Us: Home Page: freescale.com Web Support: freescale.com/support Information in this document is provided solely to enable system and software implementers to use Freescale products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document. Freescale reserves the right to make changes without further notice to any products herein. Freescale makes no warranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters that may be provided in Freescale data sheets and/or specifications can and do vary in different applications, and actual performance may vary over time. All operating parameters, including “typicals,” must be validated for each customer application by customer's technical experts. Freescale does not convey any license under its patent rights nor the rights of others. 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