Document
Low Cost, ±2 g Dual Axis Accelerometer with Analog Outputs
MXA2312A
FEATURES
Dual axis accelerometer fabricated on a monolithic CMOS IC On-chip mixed mode signal processing Resolution better than 2 milli-g 50,000 g shock survival rating 30 Hz bandwidth expandable to >160 Hz 2.70V to 5.25V single supply operation Small (5mm x 5mm x 2mm) surface mount package Continuous self test Independent axis programmability (special order)
Sck (optional)
Internal Oscillator Temperature Sensor Voltage Reference Continous Self Test
Tout
CLK
Vref
Heater Control
X axis
Low Pass Filter
Aout X
APPLICATIONS
Automotive – Vehicle Security/Active Suspension/ABS HED Angle Control/Tilt Sensing Security – Gas Line/Elevator/Fatigue Sensing Office Equipment – Computer Peripherals/PDA’s/Mouse Smart Pens/Cell Phones Gaming – Joystick/RF Interface/Menu Selection/Tilt Sensing White Goods – Spin/Vibration Control
2-AXIS SENSOR
Factory Adjust Offset & Gain Low Pass Filter
Y axis
Aout Y
Vdd
Gnd
Vda
MXA2312A FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION The MXA2312A is a very low cost, dual axis accelerometer fabricated on a standard, submicron CMOS process. The MXA2312A measures acceleration with a full-scale range of ±2 g and a sensitivity of 312mV/g at 25°C. (The MEMSIC accelerometer product line extends from ±1 g to ±10 g with custom versions available above ±10 g.) It can measure both dynamic acceleration (e.g., vibration) and static acceleration (e.g., gravity). The MXA2312A 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 up to 50,000 g, leading to significantly lower failure rates and lower loss due to handling during assembly. The MXA2312A provides an absolute analog output (ref. other MEMSIC data sheets for ratiometric, analog or digital outputs). The typical noise floor is 0.75 mg/ Hz allowing
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.
signals below 2 milli-g to be resolved at 1 Hz bandwidth. The 3dB rolloff of the device occurs at 30 Hz but is expandable to >160 Hz (refernce Application Note AN00MX-003). The MXA2312A is available in a low profile LCC surface mount package (5mm x 5mm x 2mm height). It is hermetically sealed and are operational over a -40°C to +105°C temperature range. Due to the standard CMOS structure of the MXA2312A, additional circuitry can easily be incorporated into custom versions for high volume applications. Contact the factory for more information.
MEMSIC, Inc. 100 Burtt Road, Andover, MA 01810 Tel: 978.623.8188 Fax: 978.623.9945 www.memsic.com
www.DataSheet.in
MXA2312A SPECIFICATIONS (Measurements @ 25°C, Acceleration = 0 g unless otherwise noted; VDD, VDA = 5.0V
unless otherwise specified)
Parameter SENSOR INPUT Measurement Range1 Nonlinearity Alignment Error2 Transverse Sensitivity3 SENSITIVITY Sensitivity, Analog Outputs at pins AOUTX and AOUTY6 Change over Temperature (uncompensated)4 Change over Temperature (compensated) 4 ZERO g BIAS LEVEL 0 g Offset6 0 g Voltage6 0 g Offset over Temperature NOISE PERFORMANCE Noise Density, rms FREQUENCY RESPONSE 3dB Bandwidth - uncompensated 3dB Bandwidth - compensated5 TEMPERATURE OUTPUT Tout Voltage Sensitivity VOLTAGE REFERENCE VRef Change over Temperature Current Drive Capability SELF TEST Continuous Voltage at AOUTX, AOUTY under Failure Continuous Voltage at AOUTX, AOUTY under Failure AOUTX and AOUTY OUTPUTS Normal Output Range Current Turn-On Time POWER SUPPLY Operating Voltage Range Supply Current Supply Current6,7 TEMPERATURE RANGE Operating Range NOTES
Guaranteed by measurement of initial offset and sensitivity. 2 Alignment error is specified as the angle between the true and indicated axis of sensitivity. 3 Transverse sensitivity is the algebraic sum of the alignment and the inherent sensitivity errors. 4 The sensitivity change over temperature for thermal accelerometers is based on variations in heat transfer that are governed by the laws of physics and it is highly consistent from device to device. Please refer to the section in this data sheet titled “Compensation for the Change of Sensitivity over Temperature” for more information. 5 External circuitry is required to extend the 3dB bandwidth.
1
Conditions Each Axis Best fit straight line
Min ±2.0
MXA2312A Typ
Max
Units g % of FS degrees %
1.0 ±1.0 ±2.0
2.0
Each Axis @5.0V supply ∆ from 25°C, at –40°C ∆ from 25°C, at +105°C ∆ from 25°C, –40°C to +105°C Each Axis ∆ from 25°C ∆ from 25°C, based on 312mV/g Without frequency compensation 280 -47 <3.0 -0.5 1.09 0.00 1.25 ±2.0 ±0.62 0.75 30 >160 1.15 4.6 @2.7V-5.0V supply Source @5.0V Supply, output rails to supply volta.