MXD7202NL

Low Cost, Low Noise ±2 g Dual Axis Accelerometer with Digital Outputs MXD7202GL/HL/ML/NL FEATURES Low cost Resolution better than 1 milli-g Dual axis accelerometer fabricated on a monolithic CMOS IC On chip mixed signal processing No moving parts; No loose particle issues >50,000 g shock survival rating 5mm X 5mm X 2mm LCC package 2.7V to 5.25V single supply continuous operation Compensated for Sensitivity over temperature Ultra low initial Zero-g Offset No adjustment needed outside APPLICATIONS Security – Gas Line/Elevator/Fatigue Sensing Information Appliances – Computer Peripherals/PDA’s/Mouse Smart Pens/Cell Phones Gaming – Joystick/RF Interface/Menu Selection/Tilt Sensing GPS – electronic Compass tilt Correction Consumer – LCD projectors, pedometers, blood pressure Monitor, digital cameras GENERAL DESCRIPTION The MXD7202GL/HL/ML/NL is a low cost, dual axis accelerometer fabricated on a standard, submicron CMOS process. It is a complete sensing system with on-chip mixed signal processing. The MXD7202GL/HL/ML/NL measures acceleration with a full-scale range of ±2 g and a sensitivity of 12.5%/g @5V. It can measure both dynamic acceleration (e.g. vibration) and static acceleration (e.g. gravity). The MXD7202GL/HL/ML/NL design is based on heat convection and requires no solid proof mass. This eliminates stiction and particle problems associated with competitive devices and provides shock survival greater than 50,000 g, leading to significantly lower failure rate and lower loss due to handling during assembly and at customer field application. Information furnished by MEMSIC is believed to be accurate and reliable. However, no responsibility is assumed by MEMSIC for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of MEMSIC. MXD7202GL/HL/ML/NL FUNCTIONAL BLOCK DIAGRAM The MXD7202GL/HL/ML/NL provides two digital outputs that are set to 50% duty cycle at zero g acceleration. The outputs are digital with duty cycles (ratio of pulse width to period) that are proportional to acceleration. The duty cycle outputs can be directly interfaced to a microprocessor. The typical noise floor is 0.3 mg/ Hz allowing signals below 1 milli-g to be resolved at 1 Hz bandwidth. The MXD7202GL/HL/ML/NL is packaged in a hermetically sealed LCC surface mount package (5 mm x 5 mm x 2 mm height) and is operational over a 0°C to 70°C(GL/HL) or a 40°C to +85°C(ML/NL) temperature range. MEMSIC, Inc. 800 Turnpike St., Suite 202, North Andover, MA 01845 Tel: 978.738.0900 Fax: 978.738.0196 www.memsic.co MEMSIC MXD7202GL/HL/ML/NL Page 1 of 10 2003.08.04 MXD7202GL/HL/ML/NL SPECIFICATIONS (Measurements @ 25°C, Acceleration = 0 g unless otherwise noted; VDD = 5.0V unless otherwise specified) MXD7202GL/H Parameter SENSOR INPUT Measurement Range Nonlinearity Alignment Error 2 1 MXD7202ML/N Max Min. L Typ. ±2.0 g 0.5 ±1.0 0.01 ±0.5 % of FS degrees Degrees % Max. Units Conditions Each Axis Min L Typ. ±2.0 Best fit straight line 0.5 ±1.0 X Sensor to Y Sensor 3 Alignment Error Cross Axis Sensitivity SENSITIVITY Duty cycle per g Duty cycle per g Sensitivity Change over Temperature4 ZERO g BIAS LEVEL 0 g Duty cycle 0 g Duty cycle 0 g Duty cycle 0 g Duty cycle 0 g Offset vs. Temperature NOISE PERFORMANCE Noise Density, rms FREQUENCY RESPONSE 3dB Bandwidth DUTY CYCLE OUTPUT STAGE Output High Voltage Output Low Voltage Current T25 Drift vs. Temperature Rise/Fall Time POWER SUPPLY Operating Voltage Range Quiescent Supply Current Quiescent Supply Current Turn-On Time TEMPERATURE RANGE Operating Range 4 0.01 ±0.5 Each Axis VDD=5.0V VDD=3.0V Delta from 25°C Each Axis VDD=5.0V VDD=5.0V VDD=3.0V VDD=3.0V Delta from 25°C @25°C 47 -0.24 46 -0.32 50 0.00 50 0.00 1.5 53 0.24 54 0.32 47 -0.24 46 -0.32 50 0.00 50 0.00 1.5 53 0.24 54 0.32 % g % g mg/°C 11.5 11.3 12.5 12.5 13.5 13.7 10 11.5 11.3 12.5 12.5 13.5 13.7 15 %/g %/g % 0.3 0.8 0.3 0.8 mg/ Hz Hz V 19 Vs-0.2V 0.2 Source or sink @ 3.0V- 5.0V Supply -900 -750 200 -600 -900 250 Vs-0.2V 19 0.2 250 -750 200 -600 V uA ppm/°C ns 2.7 @5.0V @3.0V Level (0g) 3.0 3.4 100 5.25 3.8 4.3 2.7 3.0 3.4 100 5.25 3.8 4.3 V mA mA mS °C 0 3 +70 -40 +85 NOTES 1 2 Guaranteed by measurement of initial offset and sensitivity. Cross axis sensitivity is the algebraic sum of the alignment and the inherent sensitivity errors. 4 Defined as the output change from ambient to maximum temperature or ambient to minimum temperature. 5 Duty cycle period Alignment error is specified as the angle between the true and indicated axis of sensitivity. MEMSIC MXD7202GL/HL/ML/NL Page 2 of 10 2003.08.04 ABSOLUTE MAXIMUM RATINGS* Supply Voltage (VDD) ………………...-0.5 to +7.0V Storage Temperature ……….…………-65°C to +150°C Acceleration ……………………………………..50,000 g *Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; the functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Pin Description: LCC-8 Package Pin Name Description 1 NC Do Not Connect 2 TP Connected to ground 3 COM Common 4 Yout Y Channel Duty Cycle Output 5 Xout X Channel Duty Cycle Output 6 NC Do Not Connect 7 NC Do Not Connect 8 VDD 2.7V to 5.25V Ordering Guide Model MXD7202GL MXD7202HL MXD7202ML MXD7202NL PWM Frequency THEORY OF OPERATION The MEMSIC device is a complete dual-axis acceleration measurement system fabricated on a monolithic CMOS IC process. The device operation is based on heat transfer by natural convection and operates like other accelerometers having a proof mass. The stationary element, or ‘proof mass’, in the MEMSIC sensor is a gas. A single heat source, centered in the silicon chip is suspended across a cavity. Equally spaced aluminum/polysilicon thermopiles (groups of thermocouples) are located equidistantly on all four sides of the heat source (dual axis). Under zero acceleration, a temperature gradient is symmetrical about the heat source, so that the temperature is the same at all four thermopiles, causing them to output the same voltage. Acceleration in any direction will disturb the temperature profile, due to free convection heat transfer, causing it to be asymmetrical. The temperature, and hence voltage output of the four thermopiles will then be different. The differential voltage at the thermopile outputs is directly proportional to the acceleration. There are two identical acceleration signal paths on the accelerometer, one to measure acceleration in the x-axis and one to measure acceleration in the y-axis. Please visit the MEMSIC website at www.memsic.com for a picture/graphic description of the free convection heat transfer principle. Temperature Range 0 to 70°C 0 to 70°C -40 to +85°C -40 to +85°C Device Weight