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MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
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Micromachined Accelerometer
The XMMA series of silicon capacitive, micromachined accelerometers features; signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. The XMMA series of accelerometers is suitable for automotive crash detection and recording, vibration monitoring, automotive suspension control, appliance control systems, etc. Features * Minimum Full Scale Measurement 44g * Calibrated, Self-Test * Integral Signal Conditioning and 4-Pole Filter * Linear Output * Robust, High Shock Survivability * Ratiometric * G-Cell, Hermetically Sealed at Wafer Level * Two Packaging Options Available: 1) Plastic DIP for Z Axis Sensing (XMMA1000P) 2) Wingback for X Axis Sensing (XMMA2000W) Typical Applications * Automotive Crash Detection and Recording * Automotive Suspension Control * Vibration Monitoring and Recording * Appliance Control * Mechanical Bearing Monitoring * Computer Hard Drive Protection * Computer Mouse and Joysticks * Virtual Reality Input Devices * Sports Diagnostic Devices and Systems
XMMA1000P XMMA2000W
XMMA1000: Z AXIS SENSITIVITY XMMA2000: X AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 50g
10 9 12 11 14 13 16 15
78 56 34 12
DIP PACKAGE CASE 648C-03 XMMA1000P
1
2
3
4
5
6
WB PACKAGE CASE 456-03 XMMA2000W
SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM
VDD G-CELL SENSOR INTEGRATOR GAIN FILTER TEMP COMP VOUT
VST
SELF-TEST
CONTROL LOGIC & EPROM TRIM CIRCUITS
OSCILLATOR
CLOCK GEN. VSS
Senseon is a trademark of Motorola, Inc. Replaces MMA1000P/D
Motorola Sensor Device Data (c) Motorola, Inc. 1997
1
XMMA1000P XMMA2000W
MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
Rating Powered Acceleration (all axis) Unpowered Acceleration (all axis) Supply Voltage Drop Test(1) Storage Temperature Range Symbol Gpd Gupd VDD Ddrop Tstg Value 500 2000 -0.3 to +7.0 1.2 - 40 to +105 Unit g g V m C
OPERATING RANGE (These limits define the range of operation for which the part will meet specification.)
Characteristic Supply Voltage(2) Supply Current Operating Temperature Range Symbol VDD IDD TA Min 4.75 1.0 - 40 Typ 5.0 4.0 -- Max 5.25 5.0 +85 Unit V mA C
NOTES: 1. Dropped onto concrete surface from any axis. 2. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration.
ELECTRO STATIC DISCHARGE (ESD)
Due to the technological advancing semiconductor industry, it has now become increasingly important for semiconductor manufacturers, users of semiconductors and other electronic components to fully understand the nature and sources of ESD. More importantly, a thorough understanding of its impact on quality and reliability must be understood. Whereas the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over 2000 volts can accumulate on the human body or associated Automated Test Equipment (ATE). A charge of this magnitude can alter the performance or cause failure of the chip. When proper ESD precautions are followed the discharges will not be detrimental to the chips performance.
Q. What is the orientation of the g-force in relation to the output voltage? A. The accelerometer responds to g forces perpendicular to the plane of the package. For acceleration directed onto the top of the package, the output voltage will increase above the nominal 2.5 V. For acceleration directed away from the top of the package, the output will decrease below 2.5 V. Refer to the "Positive Acceleration Sensing Direction'' diagram on page 7. Q. What is the resonant frequency of the g-cell? A. The accelerometer's g-cell is overdamped. The first resonant mode of the package is 10 kHz for the DIP and 5 kHz for the Wingback. Q. What is ratiometricity? A. Ratiometricity is the sensors ability to track changes in supply voltage. This is a key feature when interfacing to a microcontroller or an A/D converter. Ratiometricity allows for system level cancellation of supply induced errors in the analog to digital conversion process. Refer to the Special Features section under the Principle of Operation for more information. Q. Is the accelerometer device sensitive to electrostatic discharge (ESD)? A. Yes . . . the SENSEON accelerometer should be handled like other CMOS technology devices. Q. Can the g-cell part "latch''? A. No, overrange stops have been designed into the g-cell to prevent latching. (Latching is when the middle plate of the g-cell sticks to either the upper or lower plate.)
FREQUENTLY ASKED QUESTIONS
Q. What is the g-cell? A. The g-cell is the acceleration transducer within the accelerometer device. It is hermetically sealed at the wafer level to ensure a contaminant free environment, resulting in superior reliability performance. Q. What does the output typically interface with? A. The accelerometer device is designed to interface with an analog to digital converter available on most microcontrollers. The output has a 2.5 V DC offset, therefore positive and negative acceleration is measurable.
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Motorola Sensor Device Data
XMMA1000P XMMA2000W
OPERATING CHARACTERISTICS
(Unless otherwise noted: -40
v TA v +85, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1))
Symbol S S VOFF VOFF G VN Min 37.2 7.36 2.2 0.44 VDD 44 -- -- 360 20 -- 3.7 30 -- -- 0.3 -- -- -- -- -- -- Typ 40 8.0 2.5 0.5 VDD 50 -- 2.0 400 25 -- -- 60 2.0 0.2 -- -- 300 Max 42.8 8.64 2.8 0.56 VDD -- 3.5 -- 440 30 1.4 -- 120 -- -- VDD Unit mV/g mV/V/g V V g mVrms mVpk Hz g V V A ms ms V pF % FSO degrees % FSO kHz
Characteristic Sensitivity (TA = 25C, VDD = 5.0 V)(2) Sensitivity(2) Zero Accel Output(3) (VDD = 5.0 V) Zero Accel Output Acceleration Range(4) Noise (10 Hz to 400 Hz)(5) Clock Noise(6) Filter Cut Off Frequency Self-Test Output Response Self-Test Input Low Self-Test Input High Self-Test Input Loading(7) Self-Test Response Time(8) Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(10) Output Impedance Nonlinearity Alignment Error Transverse Sensitivity(11) Package Resonance (DIP/WB)
F
*3dB
GST VIL VIH IIN tST --
VNC
VFSO CL ZO -- -- -- --
*0.3
100 -- -- -- -- --
"3.0
3.0 10/5
1.0
NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.01 F capacitor to ground. 2. The device is calibrated at 20g. 3. The device can measure both + and acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 4. Refer to the Principle of Operation section for a sample g range calculation. 5. Refer to the Principle of Operation section for a sample rms to peak to peak calculation. 6. At clock frequency 65 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60) to guarantee output amplifier stability. 11. A measure of the devices ability to reject an acceleration applied 90 from the true axis of sensitivity.
*
^
Motorola Sensor Device Data
3
XMMA1000P XMMA2000W
Pinout description for the Wingback package:
1 2 3 4 5
6
Pin # 1 2 3 4 5 6 --
Pin Name -- ST VOUT -- VSS VDD Wings No internal connection, tie to VSS Logic input pin to initiate self test Output voltage No internal connection, tie to VSS Signal ground Supply voltage (5 V)
Description
Support pins, internally connected to lead frame. Tie to VSS.
10 9 12 11 14 13 16 15
Pinout description for the DIP package:
78 56 34 12
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Pin Name -- -- -- ST VOUT -- VSS VDD Trim 1 Trim 2 Trim 3 Trim 4 Trim 5 -- -- -- No internal connection, tie to VSS No internal connection, tie to VSS No internal connection, tie to VSS Logic input pin to initiate self test Output voltage No internal connection, tie to VSS Signal ground Supply voltage (5 V) Used for factory trim, tie to VSS Used for factory trim, tie to VSS
Description
Used for factory trim, MUST tie to VDD Used for factory trim, tie to VSS Used for factory trim, tie to VSS No internal connection, tie to VSS No internal connection, tie to VSS No internal connection, tie to VSS
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Motorola Sensor Device Data
XMMA1000P XMMA2000W
PRINCIPLE OF OPERATION
The Motorola accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (G-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined "cap'' wafer. The G-Cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It consists of two stationary plates with a moveable plate in-between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 1). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The G-Cell plates form two back-to-back capacitors (Figure 2). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, is the dielectric constant, and D is the distance between the plates. The CMOS ASIC uses switched capacitor techniques to measure the G-Cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Table 1.
Nominal Peak to Peak Value 2.0 3.0 4.0 5.0 6.0 6.6 rms rms rms rms rms rms % Confidence Level 68% 87% 95.40% 98.80% 99.73% 99.90%
Noise rms = 3.5mVrms Noise peak to peak at a 99.9% confidence level: 3.5mVrms* 6.6 = 23.1mVpp Self-Test XMMA sensors provide a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth "plate'' is used in the g-cell as a self- test plate. This plate is fixed and is located under an extended portion of the center (moveable) plate. When the user applies a logic high input to the self-test pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection, is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the sensor are functioning. Ratiometricity The XMMA1000P and XMMA2000W are designed to be "ratiometric''. That is, their transfer function will be proportional to the applied supply voltage. This feature allows easy interfacing to common microcontrollers that use ratiometric A/D converters for system cost benefits. In operation, a ratiometric sensor's gain or "sensitivity'' will change 1:1 with applied supply voltage and the zero signal output will be at midsupply. (2.5 V for a 5 V VDD and 2.625 V for a 5.25 VDD). Minimum G Range Calculation To calculate the minimum g range values of an accelerometer several factors have to be taken into consideration. These considerations include, the supply voltage, the device's sensitivity, offset voltage and output rail. A sample calculation for the minimum g range is shown below. To complete the calculation the rail and offset voltages must be subtracted from the supply voltage, then divided by the supply voltage multiplied by the device's worst case (highest) sensitivity.
V DD 0.56V DD 0.3V V DD(8.64mV V g)
Acceleration
Figure 1.
Figure 2.
SPECIAL FEATURES
Filtering The Motorola accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cut-off frequency. Noise Calculation The noise for the Motorola accelerometer is specified as an rms value which is a statistical value of a gaussian noise source. To convert the rms values to a peak to peak value at a particular confidence level refer to Table 1. A sample calculation at a 99.9% confidence level is shown.
*
*
* 0.3V + 0.44V(0.00864) + V
DD DD
50.93
* 34.72 V
DD
g
Using the standard five volt power supply, the minimum g range is calculated to be: 50.926
* 34.722 + 43.98 [ 44g 5.00
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Motorola Sensor Device Data
XMMA1000P XMMA2000W
BASIC CONNECTIONS
Circuit Schematic Figure 3 shows the recommended connection diagram for operating the accelerometer. Figure 3 (a) shows the 16 pin DIP package version, the XMMA1000P, while (b) shows the 6 pin Wingback package version, the XMMA2000W. For the XMMA1000P, pins 1, 2, 3, 6, 14, 15, and 16 have no internal connections, and pins 9 through 13 are used for calibration and trimming in the factory. These pins should all be connected to VSS, except pin 11 which must be connected to VDD. For the XMMA2000W, pins 1 and 4, and the wings (supporting pins) should be connected to VSS.
VDD XMMA1000P LOGIC INPUT 4 ST 8 VDD C1 0.1 F 11 TRIM 3 7 VSS (a) VOUT 5 R1 1 k NOTES: OUTPUT SIGNAL * Use a .1 F capacitor on VDD to decouple the power source.
PCB Layout
ACCELEROMETER MICROCONTROLLER ST VOUT VSS VDD R 1 k C 0.1 F VRH C 0.1 F C 0.01 F P0 A/D IN
VSS C 0.1 F VDD
POWER SUPPLY
C2 0.01 F
VDD
XMMA2000W LOGIC INPUT 2 ST 6 VDD VOUT 3 R1 1 k
OUTPUT SIGNAL
C1 0.1 F 5 VSS (b)
C2 0.01 F
Figure 3. Accelerometers with Recommended Connection Diagram
* Physical coupling distance of the accelerometer to the microcontroller should be minimal. * Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown above. * Use independent supply traces for the A/D reference (microcontroller) and the accelerometer. * Use an RC filter of 1 k and 0.01 F on the output of the accelerometer to minimize induced errors. * PCB layout of power and ground should not couple power supply noise. * Accelerometer and microcontroller should not be a high current path. * For ratiometricity purposes the accelerometer VDD and microcontroller A/D reference pin should be on the same trace. * A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors.
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters which may be provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer.
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Motorola Sensor Device Data
XMMA1000P XMMA2000W
Positive Acceleration Sensing Direction
DIP PACKAGE
WINGBACK PACKAGE
12 16 9
7
1
8 1 6
* *
* When positioned as shown, the Earth's gravity will result in a positive 1g output
Drilling Patterns
WB PACKAGE DRILLING PATTERN
.000 .100 .200 .300 .400 .500 0.088 0.588 .045 2X
.095 2X .13 .000 .030 6X PIN 1
.627
Measurement in inches
ORDERING INFORMATION
Device XMMA1000P XMMA2000W Temperature Range -40 to +85C -40 to +85C Case No. Case 648C-03 Case 456-03 Package Plastic DIP Plastic Wingback
Motorola Sensor Device Data
7
XMMA1000P XMMA2000W
PACKAGE DIMENSIONS
-A-
16 9
L
-B-
1 8
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. INTERNAL LEAD CONNECTION BETWEEN 4 AND 5, 12 AND 13.
M
NOTE 5
J C -T-
SEATING PLANE
16 PL M
0.13 (0.005) K
TB
S
N F E G D 16 PL 0.13 (0.005)
M
TA
S
CASE 648C-03 ISSUE C DIP PACKAGE
DIM A B C D E F G J K L M N
INCHES MIN MAX 0.740 0.840 0.240 0.260 0.145 0.185 0.015 0.021 0.050 BSC 0.040 0.70 0.100 BSC 0.008 0.015 0.115 0.135 0.300 BSC 0_ 10_ 0.015 0.040
MILLIMETERS MIN MAX 18.80 21.34 6.10 6.60 3.69 4.69 0.38 0.53 1.27 BSC 1.02 1.78 2.54 BSC 0.20 0.38 2.92 3.43 7.62 BSC 0_ 10_ 0.39 1.01
-A- C
12 7 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. INCHES MIN MAX 0.618 0.638 0.250 0.270 0.130 0.135 0.015 0.021 0.328 0.368 0.112 0.120 0.100 BSC 0.050 BSC 0.009 0.012 0.125 0.140 0.063 0.070 0.015 0.025 0.036 0.044 0.110 0.120 0.025 0.035 MILLIMETERS MIN MAX 15.70 16.21 6.35 6.86 3.30 3.43 0.38 0.53 8.33 9.35 2.84 3.05 2.54 BSC 1.27 BSC 0.23 0.30 3.18 3.56 1.60 1.78 0.38 0.64 0.91 1.12 2.79 3.05 0.64 0.89
-B-
1 6
K M G E H 0.13 (0.005)
M
L
D
6 PL
J
M
TA
B
M
S N P
DIM A B C D E F G H J K L M N P S
F
-T-
CASE 456-03 ISSUE D WB PACKAGE
Mfax is a trademark of Motorola, Inc. How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 5405, Denver, Colorado 80217. 1-303-675-2140 or 1-800-441-2447 Customer Focus Center: 1-800-521-6274 MfaxTM: RMFAX0@email.sps.mot.com - TOUCHTONE 1-602-244-6609 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, Motorola Fax Back System - US & Canada ONLY 1-800-774-1848 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852-26629298 - http://sps.motorola.com/mfax/ HOME PAGE: http://motorola.com/sps/ JAPAN: Nippon Motorola Ltd.: SPD, Strategic Planning Office, 4-32-1, Nishi-Gotanda, Shinagawa-ku, Tokyo 141, Japan. 81-3-5487-8488
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Motorola SensorXMMA1000P/D Device Data

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