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 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. FEATURES A patented self-test feature is also built into the sensor. By Surface Mount Package applying a voltage to the self-test pin, an electrostatic force is 0.5% Non-linearity (Typical) created that attracts the seismic mass towards the top cap, Self Test Function Dc Response Built-in Damping Built-in Overrange Stops simulating an acceleration and allowing proper sensor function to be verified. DIMENSIONS STANDARD RANGES 2-8 Range g 25 50 100 250 500 Accelerometer - Amplified Model 3255 PC Board Mountable Accelerometer PERFORMANCE SPECIFICATIONS Supply Current: 5.0 VDC Ambient Temperature: 25C (Unless otherwise specified) RANGE PARAMETERS Bandwidth (MIN) Sensitivity (MIN / TYP/ MAX) 25G 50G 100G UNITS 0-1000 0-1000 0-1500 Hz NOTES 8 76.0/80.0/84.0 38.0/40.0/42.0 19.0/20.0/21.0 mV/g 1, 4 NOTES RANGE PARAMETERS 250G 500G UNITS Bandwidth (MIN) 0-2000 0-2400 Hz 8 7.6/8.0/8.4 3.8/4.0/4.2 mV/g 1, 4 UNITS NOTES Sensitivity (MIN / TYP/ MAX) ALL RANGES PARAMETERS MIN TYP MAX Zero Acceleration Output 2.3 2.5 2.7 Volts 1, 4 0.2 1.0 % Span 2 1 3 % Span 5.0 7.0 Volts 10 mA Non-Linearity Transverse Sensitivity Supply Voltage 4.5 Supply Current Output Noise 10 Self-Test Input Voltage Self-Test Response (Vst = -5V) -30 -0.89 Self-Test Accuracy mV p-p 5 Volts 6, 7 -2.07 G 6, 7 0.1 mA 6, 7 5 % 4, 6, 7 0 -1.48 Self-Test Input Current (Vst = -5V) -5 Output Source Current (load to ground) 1.0 mA Output Sink Current (supply to load) 0.5 mA Acceleration Limits Operating Temperature 3 2000 G -40C to +85C Storage Temperature -40C to +125C Weight 1.5 Grams Notes 1. The output voltage increases from the Zero Acceleration Output for positive acceleration and decreases for negative acceleration. 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. 2. Best Fit Straight Line. 8. 3. Output is ratio metric with supply voltage in the range of (5.0 0.5) V. The useful frequency range is defined as the range of frequencies over which the device sensitivity is within 5% of the DC value. 4. Includes effects over operating temperature range. 9. 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. 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 PAD FUNCTION 1 Alarm Function 2 Signal Output 3 Ground 4 +5V Supply 5 6 thru 11 Self Test No Electrical Connection June 2001 Accelerometer - Amplified Feel free to contact customer service with any questions at Toll free 1(800)745-8008; Phone (757)766-1500; Fax (757)766-4297 2-9