AD22301 - Analog Devices - Datasheet.Directory

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

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.

400Hz

Bessel

Filter

Differential

Sensor

Self Test

AD22300/1

XOUT

Exc

Timing

Generator

Vdd

Demod

Amp

Vdd2

400Hz

Bessel

Filter

Differential

Sensor

Self Test

AD22302

YOUT

Exc

Timing

Generator

Vdd

Demod

Amp

Vdd2

Vs 400Hz

Bessel

Filter

Differential

Sensor

XOUT

Exc Demod

Amp

Vdd3

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 2

AD22300, AD22301 - AUTOMOTIVE GRADE SPECIFICATIONS

( @ TA = -40°C to +105°C, 3.3V DC ± 5%, Acceleration = 0g; unless otherwise noted)

AD22300 AD22301

Conditions min typ max min typ max units

Sensor

Output Full Scale Range IOUT≤ ±100µA ±37 ±70 g

IOUT ≤ ±250µA ±35 ±67 g

Nonlinearity 0.2 2 0.2 2 %

Package alignment error 1 1 degree

Cross-axis sensitivity -5 5 -5 5 %

Resonant frequency 24 24 kHz

Sensitivity, Ratiometric Vdd=3.3V, 100Hz, 25C 33.94 36.3 38.66 16.66 17.82 18.98 mV/g

-6.5 6.5 -6.5 6.5 %

Vdd=3.3V±5%, 100Hz, temp 10.28 11 11.72 5.05 5.4 5.75 mV/V/gee

-6.5 6.5 -6.5 6.5 %

Offset

Zero-g output voltage Vdd=3.3V, 25C 1.51 1.65 1.79 1.56 1.65 1.74 V

error over temp -42.42 42.42 -27.27 27.27 mV/V

Noise

Noise density 10Hz-400Hz, 3.3V 1.67 4.6 2.7 5.3 mg/rt Hz

Clock Noise 3.3 3.3 mV p-p

Frequency Response 2 pole Bessel

-3dB frequency 360 400 440 360 400 440 Hz

-3dB frequency drift 25 deg C to TMIN or TMAX 6 6 Hz

Self Test

Output change (cubic vs. Vdd) Vdd=3.3V 108 158 212 60 90 120 mV

Logic input high Vdd-0.8 Vdd-0.8 V

Logic input low 0.8 0.8 V

Turn on time to 90% of final value 1 1 ms

Input resistance pull-down resistor to ground 30 50 30 50 kΩ

Output Amplifier

Output voltage swing IOUT≤ ±100µA 0.1 Vdd-0.1 0.1 Vdd-0.1 V

IOUT ≤ ±250µA 0.25 Vdd-0.25 0.25 Vdd-0.25 V

Capacitive load drive 1000 1000 pF

Pre-filter Headroom 210 420 g

CFSR 5 3 V/V

Power Supply (Vdd) 3.135 3.3 3.465 3.135 3.3 3.465 V

Functional Voltage Range 3.135 6 3.135 6 V

Supply current 0.4 0.8 2 0.4 0.8 2 mA

Temperature Range -40 105 -40 105 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

AD22302 - AUTOMOTIVE GRADE SPECIFICATIONS

( @ TA = -40°C to +105°C, 3.3V DC ± 5%, Acceleration = 0g; unless otherwise noted)

AD22302

Conditions min typ max units

Sensor

Output Full Scale Range IOUT≤ ±100µA x axis:

y axis:

±70

±37

IOUT ≤ ±250µA x axis:

y axis:

±67

±35

Nonlinearity 0.2 2 %

Package alignment error 1 degree

Sensor to sensor alignment error 0.1 degree

Cross-axis sensitivity -5 5 %

Resonant frequency 24 kHz

Sensitivity, Ratiometric Vdd=3.3V, 100Hz, 25C x: 16.66 17.82 18.98 mV/g

-6.5 6.5 %

y: 33.94 36.3 38.66 mV/g

-6.5 6.5 %

Vdd=3.3V± 5%, 100Hz, temp x: 5.05 5.4 5.75 mV/V/gee

-6.5 6.5 %

y: 10.28 11 11.72 mV/g

-6.5 6.5 %

Offset

Zero-g output voltage Vdd=3.3V, 25C x: 1.56 1.65 1.74 V

error over temp -27.27 27.27 mV/V

Vdd=3.3V, 25C y: 1.51 1.65 1.79 V

error over temp -42.42 42.42 mV/V

Noise

Noise density 10Hz-400Hz, 3.3V x: 2.7 5.3 mg/rt Hz

y: 1.67 4.6 mg/rt Hz

Clock Noise x / y: 3.3 mV p-p

Frequency Response 2 pole Bessel

-3dB frequency 360 400 440 Hz

-3dB frequency drift 25 deg C to TMIN or TMAX 6 Hz

Self Test

Output change (cubic vs. Vdd) Vdd=3.3V x: 60 90 120 mV

y: 108 158 212 mV

Logic input high Vdd-0.8 V

Logic input low 0.8 V

Turn on time to 90% of final value 1 ms

Input resistance pull-down resistor to ground 30 50 kΩ

Output Amplifier

Output voltage swing IOUT≤ ±100µA x / y : 0.1 Vdd-0.1 V

IOUT ≤ ±250µA x / y : 0.25 Vdd-0.25 V

Capacitive load drive 1000 pF

Pre-filter Headroom x:

420

210

CFSR x:

V/V

Power Supply (Vdd) 3.135 3.3 3.465 V

Functional Voltage Range 3.135 6 V

Supply current 0.6 1.0 2 mA

Temperature Range -40 105 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 4

ABSOLUTE MAXIMUM RATINGS*

Acceleration (Any Axis, Unpowered and Powered) 4000 g

Supply Voltage Vs -0.3 to 7.0V

Output Short Circuit Duration (Vout, to Ground) Indefinite

Storage Temperature -65°C to 150°C

Soldering Temperature Range (Soldering 10 sec) 245°C

Drop Test 1.2 m

Operating Temp Range -55°C to 125°C

* 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 G Range Branding

AD22300 ± 35g AD22300

AD22301 ± 70g AD22301

AD22302 ± 70g X, ± 35g Y AD22302

PIN FUNCTION DESCRIPTIONS

8-Pin LCC

(Dimensions are nominal only. For tolerances, see the Package Outline Drawing for this part.)

Pin AD22300/01 Description

1 NC No internal connection

2 NC No internal connection

3 COM Common (connected to package lid)

4 Self-Test Self Test Input

5 NC No internal connection

6 Xout Voltage Output X

7 Vdd Power Supply

8 Vdd2 Power Supply

Pin AD22302 Description

1 Vdd3 Power Supply

2 Yout Voltage Output Y

3 COM Common(connected to package lid)

4 Self-Test Self Test Input

5 NC No internal connection

6 Xout Voltage Output X

7 Vdd Power Supply

8 Vdd2 Power Supply

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

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.

MOVABLE

FRAME

ACCELERATION

Figure 1. Simplified View of Sensor Under Acceleration

UNIT FORCING

CELL

UNIT SENSING

CELL

MOVING

PLATE

FIXED

PLATES

PLATE

CAPACITORS

ANCHOR

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 self-

test 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.