SILICON DESIGNS, INC
SENSOR: Capacitive Micromachined
Nitrogen Damped Hermetically Sealed ___ Low Noise: 5 g/Hz typical for 2g Full Scale Version Internal Temperature Sensor ±4V Differential Output or 0.5V to 4.5V Single Ended Output Fully Calibrated Responds to DC & AC Acceleration -55 to +125 °C Operation +5 VDC, 8 mA Power (typical) Non-Standard g Ranges Available Integrated Sensor & Amplifier LCC or J-Lead Surface Mount Package Serialized for Traceability Pin Compatible with Model 1210
Model 1221 LOW NOISE ANALOG ACCELEROMETER
ORDERING INFORMATION
Full Scale Acceleration ±2 g ±5 g ±10 g ±25 g ±50 g ±100 g ±200 g ±400 g Hermetic Packages 20 pin LCC 20 pin JLCC 1221L-002 1221J-002 1221L-005 1221J-005 1221L-010 1221J-010 1221L-025 1221J-025 1221L-050 1221J-050 1221L-100 1221J-100 1221L-200 1221J-200 1221L-400 1221J-400
'(6&5,37,21
The Model 1221 is a low-cost, integrated accelerometer for use in zero to medium frequency instrumentation applications that require extremely low noise. The 2g version is ideally suited for seismic applications. Each miniature, hermetically sealed package combines a micro-machined capacitive sense element and a custom integrated circuit that includes a sense amplifier and differential output stage. It is relatively insensitive to temperature changes and thermal gradients. Each device is marked with a serial number on its bottom surface for traceability. An optional calibration test sheet (1221-TST) is also available which lists the measured bias, scale factor, linearity, operating current and frequency response.
23(5$7,21
The Model 1221 produces two analog output voltages which vary with acceleration as shown in the figure below. The outputs can be used either in differential or single ended mode referenced to +2.5 volts. Two reference voltages, +5.0 and +2.5 volts (nominal), are required; the output scale factor is ratiometric to the +5 volt reference voltage, and both outputs at zero acceleration are equal to the +2.5 volt reference. The sensitive axis is perpendicular to the bottom of the package, with positive acceleration defined as a force pushing on the bottom of the package.
$33/,&$7,216
Seismic Monitoring Earthquake Detection Security Systems Machine Control Modal Analysis Instrumentation Appliances Robotics Crash Testing Vibration Monitoring Vibration Analysis Vehicle Dynamics
Silicon Designs, Inc. 1445 NW Mall Street, Issaquah, WA 98027-5344 web site: www.silicondesigns.com [page 1]
Phone: 425-391-8329
Fax: 425-391-0446 Aug 05
Model 1221 Low Noise Analog Accelerometer
6,*1$/'(6&5,37,216
VDD and GND (power): Pins (9,11,14) and (2,5,6,18,19) respectively. Power (+5 Volts DC) and ground. AOP and AON (output): Pins 12 and 16 respectively. Analog output voltages proportional to acceleration. The AOP voltage increases (AON decreases) with positive acceleration; at zero acceleration both outputs are nominally equal to the +2.5 volt reference. The device experiences positive (+1g) acceleration with its lid facing up in the earth’s gravitational field. Either output can be used individually or the two outputs can be used differentially but differential mode is recommended for both lowest noise and highest accuracy operation. Voltages can be measured ratiometrically to VR for good accuracy without requiring a precision reference voltage. (See plot.) DV (input): Pin 4. Deflection Voltage. Normally left open. A test input that applies an electrostatic force to the sense element, simulating a positive acceleration. The nominal voltage at this pin is ½ VDD. DV voltages higher than required to bring the output to positive full scale may cause device damage. VR (input): Pin 3. Voltage Reference. Tie directly to VDD for ratiometric measurements or to a +5V reference for better absolute accuracy. A 0.1 F bypass capacitor is recommended at this pin. 2.5 Volt (input): Pin 17. Voltage Reference. Tie to a resistive voltage divider from +5 volts or to a +2.5 volt reference voltage. IT (output): Pin 8. Temperature dependent current source. (May be tied to VDD; see full description on page 5).
! # # - by Model:
MODEL NUMBER
VDD=VR=5.0 VDC, TC=25°C. 1221x-002 1221x-005 1221x-010 1221x-025 1221x-050 1221x-100 1221x-200 1221x-400 UNITS ±5 ±10 ±25 ±50 ±100 ±200 ±400 g 0 - 600 0 - 1000 0 - 1500 0 - 2000 0 - 2500 0 - 3500 0 - 4000 Hz 800 400 160 80 40 20 10 mV/g 7 10 25 50 100 200 400 g/(root Hz) 2000 g Note 1: Single ended sensitivity is half of values shown.
Input Range ±2 Frequency Response (Nominal, 3 dB) 0 - 400 2000 Sensitivity (Differential) 1 Output Noise (Differential, RMS, typical) 5 Max. Mechanical Shock (0.1 ms)
! # # - all Models:
PARAMETER Cross Axis Sensitivity Bias Calibration Error 2 Bias Temperature Shift (TC= -55 to +125°C) 2
Unless otherwise specified VDD=VR=5.0 VDC, TC=25°C, Differential Mode. MIN -002 -005 thru -200 -002 -005 thru -200 -250 TYP 2 2 1 100 50 1 MAX 3 4 2 300 200 2 250 0.5 1.0 2.0 UNITS % % of span (ppm of span)/°C % ppm/°C
Scale Factor Calibration Error 2, 3 Scale Factor Temperature Shift (TC= -55 to +125°C) 2 -002 thru -050 Non-Linearity -100 & -200 (-90 to +90% of Full Scale) 2, 3 -400 Power Supply Rejection Ratio Output Impedance Operating Voltage Operating Current (IDD+IVR) 2 Mass: ‘L’ package (add 0.06 grams for ‘J’ package) Note 2: Tighter tolerances available on special order.
0.3 0.5 % of span 1.0 25 dB 90 Ohms 4.75 5.0 5.25 Volts 8 10 mA 0.62 grams Note 3: 100g and greater versions are tested from -65 to +65g.
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
Silicon Designs, Inc. 1445 NW Mall Street, Issaquah, WA 98027-5344 web site: www.silicondesigns.com [page 2]
Phone: 425-391-8329
Fax: 425-391-0446 Aug 05
Model 1221 Low Noise Analog Accelerometer
$%62/87(0$;,0805$7,1*6 *
Case Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to +125°C Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -55 to +125°C Acceleration Over-range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2000g for 0.1 ms Voltage on VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to 6.5V Voltage on Any Pin (except DV) to GND 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.5V to VDD+0.5V Voltage on DV to GND 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±15V Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mW Note 4: Voltages on pins other than DV, GND or VDD may exceed 0.5 volt above or below the supply voltages provided the current is limited to 1 mA.. Note 5: The application of DV voltages higher than required to bring the output to positive full scale may cause device damage.
* NOTICE: Stresses greater than those listed above may cause permanent damage to the device. These are stress ratings only. Functional operation of the device at or above these conditions is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
PINOUT RECOMMENDED CONNECTIONS
(LCC & JLCC PACKAGES)
The 2.5V reference input (pin 17) may be driven from either a precision voltage source by the capacitively bypassed resistive divider shown above.
DEFLECTION VOLTAGE (DV) TEST INPUT: This test input applies an electrostatic force to the sense element, simulating a positive acceleration. It has a nominal input impedance of 32 k$ and a nominal open circuit voltage of ½ VDD. For best accuracy during normal operation, this input should be left unconnected or connected to a voltage source equal to ½ of the VDD supply. The change in differential output voltage (AOP - AON) is proportional to the square of the difference between the voltage applied to the DV input (VDV) and ½ VDD. Only positive shifts in the output voltage may be generated by applying voltage to the DV input. When voltage is applied to the DV input, it should be applied gradually. The application of DV voltages greater than required to bring the output to positive full scale may cause device damage. The proportionality constant (k) varies for each device and is not characterized.
1 ∆ ( A O P − A O N ) ≈ k (V D V − 2 V D D ) 2
ESD and LATCH-UP CONSIDERATIONS: The model 1221 accelerometer is a CMOS device subject to damage from large electrostatic discharges. Diode protection is provided on the inputs and outputs but care should be exercised during handling to assure that the device is placed only on a grounded conductive surface. Individuals and tools should be grounded before coming in contact with the device. Do not insert the model 1221 into (or remove it from) a powered socket.
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
Silicon Designs, Inc. 1445 NW Mall Street, Issaquah, WA 98027-5344 web site: www.silicondesigns.com [page 3]
Phone: 425-391-8329
Fax: 425-391-0446 Aug 05
Model 1221 Low Noise Analog Accelerometer
%,$667$%,/,7
