a 3.3V Single and Dual Axis Automotive iMEMS Accelerometers AD22300, AD22301, AD22302 FEATURES * * * * * * * * * * * * * * * * * Complete Acceleration Measurement System on a Single Monolithic IC 35g, 70g and 70g/35g Ranges Available Smallest Available Package Footprint For Automotive Safety Applications 8 pin Leadless Chip Carrier Full Differential Sensor & Circuitry for High Resistance to EMI/RFI Environmentally robust packaging Complete Mechanical and Electrical Self-test on Digital Command Output Ratiometric to Supply Sensitive Axes in the Plane of the Chip High Linearity (0.2% of Full-scale) Frequency Response Down To DC Supply Voltage (3.3V) Low-Power Consumption (1.3 mA single and dual axis) Tight Sensitivity Tolerance and Zero g Offset capability Higher Output Drive Current Largest available pre-filter clipping headroom 400 Hz, 2 pole Bessel Filter GENERAL DESCRIPTION The AD22300, AD22301, and AD22302 are derivative products of the fourth generation ADXL78 family surface micromachined iMEMS accelerometers from Analog Devices with enhanced performance and lower cost. Designed for use in airbag applications, these products also provide complete cost-effective solutions useful for a wide variety of other applications. The AD22300 and AD22301 are single-axis accelerometers with g-ranges of 37g or 70g. The AD22302 is a monolithic two-axis (XY) version with the sensor axes orthogonal (90) to each other and in the plane of the chip. The AD22302 X-axis has a g-range of 70g and its Y-axis has a g-range of 37g. It can be used for sensing crashes in the front or side of the vehicle and to determine the angle of impact. The AD22300, AD22301, and AD22302 are temperature stable and accurate over the automotive temperature range, with a self-test feature that fully exercises all the mechanical and electrical elements of the sensor with a digital signal applied to a single pin. Vs AD22302 AD22300/1 Vdd Vdd2 Vs Timing Generator Vdd Exc Exc Demod Amp 400Hz Bessel Filter 400Hz Bessel Filter X OUT Demod Amp 400Hz Bessel Filter Y OUT Timing Generator XOUT Exc Self Test Demod Amp Vdd2 Vdd3 Differential Sensor Differential Sensor Differential Sensor Self Test http://www.analog.com/iMEMS All minimum and maximum specifications are guaranteed; typical values are not guaranteed nor tested. Product characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev. 03 1 AD22300, AD22301 - AUTOMOTIVE GRADE SPECIFICATIONS ( @ TA = -40C to +105C, 3.3V DC 5%, Acceleration = 0g; unless otherwise noted) AD22300 typ AD22301 Conditions min max min IOUT 100A 37 70 IOUT 250A 35 67 typ max units Sensor Output Full Scale Range 0.2 Nonlinearity -5 Cross-axis sensitivity Vdd=3.3V, 100Hz, 25C 33.94 Vdd=3.3V5%, 100Hz, temp 10.28 5 -5 38.66 6.5 -6.5 11 11.72 5.05 6.5 -6.5 -6.5 16.66 % degree 5 24 36.3 -6.5 2 1 24 Resonant frequency g 0.2 1 Package alignment error Sensitivity, Ratiometric 2 g % kHz 17.82 18.98 5.4 5.75 mV/V/gee 6.5 % 6.5 mV/g % Offset Zero-g output voltage Vdd=3.3V, 25C 1.51 error over temp -42.42 1.65 1.79 1.56 42.42 -27.27 1.65 1.74 27.27 V mV/V Noise Noise density 10Hz-400Hz, 3.3V 1.67 Frequency Response 2.7 5.3 3.3 mg/rt Hz mV p-p 2 pole Bessel 360 -3dB frequency -3dB frequency drift 4.6 3.3 Clock Noise 25 deg C to TMIN or TMAX 400 440 360 6 400 440 6 Hz Hz Self Test Output change (cubic vs. Vdd) Vdd=3.3V 108 158 212 Vdd-0.8 Logic input high 60 90 to 90% of final value Input resistance pull-down resistor to ground 0.8 1 30 50 30 mV V 0.8 Logic input low Turn on time 120 Vdd-0.8 V 1 ms 50 k Output Amplifier Output voltage swing Capacitive load drive IOUT 100A 0.1 Vdd-0.1 0.1 Vdd-0.1 V IOUT 250A 0.25 Vdd-0.25 0.25 Vdd-0.25 V 1000 Pre-filter Headroom CFSR Power Supply (Vdd) 3.135 Functional Voltage Range 3.135 Supply current 0.4 Temperature Range -40 1000 pF 210 420 5 3 3.3 0.8 3.465 3.135 6 3.135 2 0.4 105 -40 3.3 0.8 g V/V 3.465 V 6 V 2 105 All minimum and maximum specifications are guaranteed; typical values are not guaranteed nor tested. Product characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev. 03 mA deg C 2 AD22302 - AUTOMOTIVE GRADE SPECIFICATIONS ( @ TA = -40C to +105C, 3.3V DC 5%, Acceleration = 0g; unless otherwise noted) AD22302 min typ Conditions Sensor Output Full Scale Range IOUT 100A IOUT 250A Nonlinearity Package alignment error Sensor to sensor alignment error Cross-axis sensitivity Resonant frequency Sensitivity, Ratiometric x axis: y axis: x axis: y axis: -5 x: y: Vdd=3.3V 5%, 100Hz, temp x: y: Offset Zero-g output voltage Noise Noise density Clock Noise Frequency Response -3dB frequency -3dB frequency drift Self Test Output change (cubic vs. Vdd) Logic input high Logic input low Turn on time Input resistance Output Amplifier Output voltage swing Capacitive load drive Pre-filter Headroom CFSR Power Supply (Vdd) Functional Voltage Range Supply current Temperature Range 70 37 67 35 0.2 1 0.1 Vdd=3.3V, 100Hz, 25C Vdd=3.3V, 25C error over temp Vdd=3.3V, 25C error over temp 10Hz-400Hz, 3.3V x: y: max 16.66 -6.5 33.94 -6.5 5.05 -6.5 10.28 -6.5 1.56 -27.27 1.51 -42.42 x: y: x / y: 18.98 6.5 38.66 6.5 5.75 6.5 11.72 6.5 g g g g % degree degree % kHz mV/g % mV/g % mV/V/gee % mV/g % 1.74 27.27 1.79 42.42 V mV/V V mV/V 2 5 24 17.82 36.3 5.4 11 1.65 1.65 units 2.7 1.67 3.3 5.3 4.6 mg/rt Hz mg/rt Hz mV p-p 360 400 6 440 Hz Hz 60 108 Vdd-0.8 90 158 120 212 mV mV V V ms k 2 pole Bessel 25 deg C to TMIN or TMAX Vdd=3.3V x: y: 0.8 to 90% of final value pull-down resistor to ground IOUT 100A IOUT 250A 30 x/y: x/y: 1 50 0.1 0.25 1000 x: y: x: y: 3.135 3.135 0.6 -40 420 210 3 6 3.3 1.0 Vdd-0.1 V Vdd-0.25 V pF g V/V 3.465 6 2 105 V V mA deg C All minimum and maximum specifications are guaranteed; typical values are not guaranteed nor tested. Product characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev. 03 3 ABSOLUTE MAXIMUM RATINGS* Acceleration (Any Axis, Unpowered and Powered) Supply Voltage Vs Output Short Circuit Duration (Vout, to Ground) Storage Temperature Soldering Temperature Range (Soldering 10 sec) Drop Test Operating Temp Range 4000 g -0.3 to 7.0V Indefinite -65C to 150C 245C 1.2 m -55C to 125C * Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; the functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this specification is not implied. Absolute maximum ratings apply individually only, not in combination. ORDERING GUIDE Standard Devices AD22300 AD22301 AD22302 G Range Branding 35g 70g 70g X, 35g Y AD22300 AD22301 AD22302 PIN FUNCTION DESCRIPTIONS 8-Pin LCC Pin 1 2 3 4 5 6 7 8 AD22300/01 NC NC COM Self-Test NC Xout Vdd Vdd2 Description No internal connection No internal connection Common (connected to package lid) Self Test Input No internal connection Voltage Output X Power Supply Power Supply Pin 1 2 3 4 5 6 7 8 AD22302 Vdd3 Yout COM Self-Test NC Xout Vdd Vdd2 Description Power Supply Voltage Output Y Common(connected to package lid) Self Test Input No internal connection Voltage Output X Power Supply Power Supply Z (Dimensions are nominal only. For tolerances, see the Package Outline Drawing for this part.) All minimum and maximum specifications are guaranteed; typical values are not guaranteed nor tested. Product characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev. 03 4 Theory of Operation The ADXL78 family provides a fully differential sensor structure and circuit path, resulting in the industry's highest resistance to EMI/RFI effects. This latest generation uses electrical feedback with zero force feedback for improved accuracy and stability. The sensor resonant frequency is significantly higher than the signal bandwidth set by the on-chip filter, avoiding the signal analysis problems caused by resonant peaks near the signal bandwidth. Figure 1 is a simplified view of one of the differential sensor elements. Each sensor includes several differential capacitor unit cells. Each cell is composed of fixed plates attached to the substrate, and movable plates attached to the frame. Displacement of the frame changes the differential capacitance, which is measured by the on-chip circuitry. ANCHOR MOVABLE FRAME ACCELERATION PLATE CAPACITORS FIXED PLATES UNIT SENSING CELL UNIT FORCING CELL MOVING PLATE ANCHOR Figure 1. Simplified View of Sensor Under Acceleration Complementary 400kHz square waves drive the fixed plates (200 kHz for the ADXL278). Electrical feedback adjusts the amplitudes of the square waves such that the AC signal on the moving plates is zero. The feedback signal is linearly proportional to the applied acceleration. This unique feedback technique ensures that there is no net electrostatic force applied to the sensor. The differential feedback control signal is also applied to the input of the filter, where it is filtered and converted to a single-ended signal. Self-Test The fixed fingers in the forcing cells are normally kept at the same potential as that of the movable frame. When the self-test digital input is activated, the voltage on the fixed fingers on one side of the moving plate in the forcing cells is changed. This creates an attractive electrostatic force, which causes the frame to move towards those fixed fingers. The entire signal channel is active, so the sensor displacement causes a change in Vout. The ADXL78 self-test function is a comprehensive method of verifying the operation of the accelerometer. Because electrostatic force is independent of the polarity of the voltage across capacitor plates, a positive voltage is applied in half of the forcing cells, and its complement in the other half of the forcing cells. Activating self-test causes a step function force to be applied to the sensor, while the capacitive coupling term is canceled. The ADXL78 has improved selftest functionality including excellent transient response and high-speed switching capability. Arbitrary force waveforms can be applied to the sensor by modulating the self-test input, such as test signals to measure the system frequency response, or even crash signals to verify algorithms within the limits of the selftest swing. All minimum and maximum specifications are guaranteed; typical values are not guaranteed nor tested. Product characteristics and specifications are subject to change without notice. Analog Devices assumes no obligation regarding future manufacturing unless otherwise agreed to in writing. Patents pending. Rev. 03 5