常见公司问题解答-技术
Q. What is an accelerometer?
A. Please refer to the Accelerometer primer for detailed information on an accelerometer.Q. What is the basic principle of the technology?
A. This MEMS sensor operation is predicated upon the thermal laws of natural convection, and operates like other accelerometers having a static component. The stationary component (i.e., static element, or 'proof mass') in the MEMSIC sensors is a gas (air). A single heat source, centered in the silicon chip, creates a thermal gradient and thus a density gradient of the gas in the sealed package. When external forces are applied to the device(ex: acceleration, deceleration, gravity, vibration, etc.), the gas moves accordingly within the package due to its miniscule inertial mass. The applied force is detected by sensing and measuring changes in temperature around the heat source.Q. What axes of sensitivity am I able to measure?
A. Two axes are available X, Y. If a Z axis is required we recommend mounting the device on a small PC board and placing the board on its side with the axis of sensitivity in the Z plane.Q. How does the part numbering system work?
A. New Part Numbering System is composed of 9 or 10 alphanumeric characters. The standard part numbering system format is as shown below. A detailed explanation can be found on the Part Numbering System webpage.
Q. What full scale g ranges am I able to measure?
A. The standard MEMSIC parts have a full g range of +/- 1g to +/- 10g. However, higher g range (several hundreds g's) measurements are obtainable with special orders from the company. Specific parts may be selected by application or by specification on this website. Please refer to the Product Selector webpage for more details on the available standard parts.Q. What types of output is available?
A. MEMSIC accelerometers provide the widest selection of outputs from Absolute analog, PWM, ratiometric, and I2C output interface.Q. What are the package pin definitions?
A. The pin definitions are defined below. Specific details of the pin definitions can be found on the device datasheets of interest.VDD - This is the supply input for the digital circuits and the sensor heater in the accelerometer. The DC voltage should be between 2.70 and 5.25 volts. Refer to the section on PCB layout and fabrication suggestions for guidance on external parts and connections.
VDA - This is the power supply input for the analog amplifiers in the accelerometer. VDA should always be connected to VDD. Refer to the section on PCB layout and fabrication suggestions for guidance on external parts and recommended connections.
Gnd - This is the ground pin for the accelerometer.
AOUTX - This pin is the output of the x-axis acceleration sensor. The user should ensure that the load impedance is sufficiently high as to not source/sink >100uA. While the sensitivity of this axis has been programmed by MEMSIC to be the same as the sensitivity for the y-axis, the accelerometer can be programmed for non-equal sensitivities on the x- and y-axes. Contact MEMSIC for additional information.
AOUTY - This pin is the output of the y-axis acceleration sensor. The user should ensure the load impedance is sufficiently high as to not source/sink >100uA. While the sensitivity of this axis has been programmed by MEMSIC to be the same as the sensitivity for the x-axis, the accelerometer can be programmed for non-equal sensitivities on the x- and y-axes. Contact MEMSIC for additional information.
TOUT - This pin is the buffered output of the temperature sensor. The analog voltage at TOUT is an indication of the die temperature. This voltage is useful as a differential measurement of temperature from ambient and not as an absolute measurement of temperature. After correlating the voltage at TOUT to 25 ambient, the change in this voltage due to changes in the ambient temperature can be used to compensate for the change over temperature of the accelerometer offset and sensitivity.
Sck - The standard product is delivered with an internal clock option (800kHz). This pin should be grounded when operating with the internal clock. An external clock option can be specially ordered from MEMSIC, allowing the user to input a clock signal between 400kHz and 1.6MHz.
Vref - A reference voltage is available from this pin. It is set at 2.50V typical and has 100mA of drive capability
Q. What absolute ratings should I be aware of?
A. The ABSOLUTE MAXIMUM RATINGS* are:Supply Voltage (VDD, VDA)--------- -0.5 to +7.0V
Storage Temperature --------- -65 to +150
Acceleration --------- 50,000 g
Q. What features of the device will be of interest to me?
A. FEATURES:- "No" mechanical resonances
- Dual axis accelerometer fabricated on a monolithic CMOS IC
- No moving parts
- Less than 2 milli-g resolution
- No sensitivity or zero g bias hysteresis
- 50,000 g shock survival rating
- 35 Hz bandwidth expandable to >100 Hz
- 2.70V to 5.25V single supply operation
- Low height (<2.0mm) surface mount package
- Continuous failure self test
- Independently programmable axes (factory special)
Q. Can I measure constant velocity with the accelerometer?
A. Not directly. However, if you have acceleration, integrating acceleration will give you velocity and integrating velocity will give you distance.Q. In what applications would I most likely use the accelerometer?
A. You would most likely use the accelerometer to measure tilt, inclination, inertial forces, shock, or vibration.Q. Who needs accelerometer products?
A. The following industries and applications would benefit from the use of accelerometers: Consumer Market- Car alarms
- Mobile phones
- Remote controls
- Navigations/GPS
- Appliance vibration control
- Sporting goods
- PDA's
- Read drives
- Optical drives
- Computer Peripherals
- Antenna steering
- Head mounted display (gaming)
- Industrial Market
- Elevator control
- Data recorders
- Shipping recorders
- Motor/pump/compressor monitoring
- Motion control
- Robotics
- Safety
- Fusing
- Guidance and Control
- Condition monitoring
- Personal navigation
- Patient monitoring/emergency call
- Patient activity and orientation
- Hospital bed control
- Physical therapy
