2-8 Accelerometer – Amplified
Model 3255
PC Board Mountable Accelerometer
0.5 to 4.5 VDC Output
Integral Temperature Compensated
Low Cost
Frontal Impact Air Bag Systems
Side Impact Air Bag Systems
Vibration/Shock Monitoring
Crash Recorder
Aerospace
FEATURES
Surface Mount Package
±0.5% Non-linearity (Typical)
Self Test Function
Dc Response
Built-in Damping
Built-in Overrange Stops
STANDARD RANGES
Range g
±25 ●
±50 ●
±100 ●
±250 ●
±500 ●
DESCRIPTION
The Model 3255 is a two-chip accelerometer designed for low
cost surface mount applications. The package can be mounted
in one of two orientations, allowing the measurement axis to be
either parallel or perpendicular to the mounting surface without
the use of costly brackets.
This accelerometer consists of a micro machined silicon
mass suspended by multiple beams from a silicon frame.
Piezoresistors located in the beams change their resistance as the
motion of the suspended mass changes the strain in the beams.
Silicon caps on the top and bottom of the device are added to
provide over-range stops. This design provides for a very low
profile, high shock resistance, durability and built-in damping
over a wide usable bandwidth. Each sensor is individually
serialized.
A patented self-test feature is also built into the sensor. By
applying a voltage to the self-test pin, an electrostatic force is
created that attracts the seismic mass towards the top cap,
simulating an acceleration and allowing proper sensor function
to be verified.
DIMENSIONS
PC Board Mountable Accelerometer Model 3255
Accelerometer – Amplified 2-9
June 2001
PERFORMANCE SPECIFICATIONS
Supply Current: 5.0 VDC
Ambient Temperature: 25°C (Unless otherwise specified)
Notes
1. The output voltage increases from the Zero Acceleration Output for
positive acceleration and decreases for negative acceleration.
2. Best Fit Straight Line.
3. Output is ratio metric with supply voltage in the range of (5.0 ± 0.5) V.
4. Includes effects over operating temperature range.
5. 1 Hz to 10 kHz.
6. Applying the self-test input voltage simulates an acceleration. The
sensor output is proportional to the square of the voltage difference
between the self-test input and the positive supply. When not using the
self-test function, the self-test input pin should be connected to the
positive supply voltage. For detailed description refer to Technical Note
TN010.
7. Self-test input voltage is with respect to supply voltage. For example, if
supply voltage is 5 VDC then Vst = -5 V is equivalent to ground.
8. The useful frequency range is defined as the range of frequencies over
which the device sensitivity is within ±5% of the DC value.
9. The alarm output is a digital output which is 0 V during normal operation
and 5 V when the output voltage of the accelerometer die is outside the
normal range. This is the case if there is a malfunction of the
accelerometer or a broken wire bond to the sensor.
ORDERING INFORMATION CONNECTIONS
PARAMETERS
RANGE
UNITS NOTES±25G ±50G ±100G
Bandwidth (MIN) 0-1000 0-1000 0-1500 Hz 8
Sensitivity (MIN / TYP/ MAX) 76.0/80.0/84.0 38.0/40.0/42.0 19.0/20.0/21.0 mV/g 1, 4
PARAMETERS
RANGE
UNITS NOTES±250G ±500G
Bandwidth (MIN) 0-2000 0-2400 Hz 8
Sensitivity (MIN / TYP/ MAX) 7.6/8.0/8.4 3.8/4.0/4.2 mV/g 1, 4
PARAMETERS
ALL RANGES
UNITS NOTESMIN TYP MAX
Zero Acceleration Output 2.3 2.5 2.7 Vo lt s 1, 4
Non-Linearity 0.2 1.0 ±% Span 2
Transverse Sensitivity 1 3 ±% Span
Supply Voltage 4.5 5.0 7.0 Volts 3
Supply Current 10 mA
Output Noise 10 mV p-p 5
Self-Test Input Voltage -30 0Vo lt s 6, 7
Self-Test Response (Vst = -5V) -0.89 -1.48 -2.07 G 6, 7
Self-Test Input Current (Vst = -5V) 0.1 mA 6, 7
Self-Test Accuracy -5 5 % 4, 6, 7
Output Source Current (load to ground) 1.0 mA
Output Sink Current (supply to load) 0.5 mA
Acceleration Limits 2000 G
Operating Temperature -40°C to +85°C
Storage Temperature -40°C to +125°C
Weight 1.5 Grams
PAD FUNCTION
1Alarm Function
2 Signal Output
3Ground
4+5V Supply
5Self Test
6 thru 11 No Electrical Connection
Feel free to contact customer service with any questions at
Toll free 1(800)745-8008; Phone (757)766-1500; Fax (757)766-4297