AD ADXRS614BBGZ ±50â°/s yaw rate gyro Datasheet

±50°/s Yaw Rate Gyro
ADXRS614
FEATURES
GENERAL DESCRIPTION
Complete rate gyroscope on a single chip
Z-axis (yaw rate) response
High vibration rejection over wide frequency
2000 g powered shock survivability
Ratiometric to referenced supply
5 V single-supply operation
105°C operation
Self-test on digital command
Ultrasmall and light (<0.15 cc, <0.5 gram)
Temperature sensor output
RoHS compliant
The ADXRS614 is a complete angular rate sensor (gyroscope)
that uses the Analog Devices, Inc. surface-micromachining
process to create a functionally complete and low cost angular
rate sensor integrated with all required electronics on one chip.
The manufacturing technique for this device is the same high
volume BiMOS process used for high reliability automotive
airbag accelerometers.
The output signal, RATEOUT (1B, 2A), is a voltage proportional
to angular rate about the axis normal to the top surface of the
package. The output is ratiometric with respect to a provided
reference supply. A single external resistor between SUMJ and
RATEOUT can be used to lower the scale factor. An external
capacitor sets the bandwidth. Other external capacitors are
required for operation.
APPLICATIONS
Navigation systems
Inertial measurement units
Platform stabilization
Robotics
A temperature output is provided for compensation techniques.
Two digital self-test inputs electromechanically excite the sensor
to test proper operation of both the sensor and the signal
conditioning circuits. The ADXRS614 is available in a 7 mm ×
7 mm × 3 mm BGA chip scale package.
FUNCTIONAL BLOCK DIAGRAM
+5V
(ADC REF)
+5V
ST2
AVCC
100nF
ST1
SELF-TEST
TEMP
25kΩ
@ 25°C
VRATIO
100nF
ADXRS614
25kΩ
AGND
DEMOD
MECHANICAL
SENSOR
DRIVE
AMP
+5V
AC
AMP
VGA
200kΩ ±5%
VDD
CHARGE PUMP
AND VOLTAGE
REGULATOR
100nF
PGND
SUMJ
RATEOUT
100nF
22nF
22nF
COUT
06748-001
CP1 CP2 CP3 CP4 CP5
Figure 1. ADXRS614 Block Diagram
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
ADXRS614
TABLE OF CONTENTS
Features .............................................................................................. 1
Theory of Operation .........................................................................9
Applications....................................................................................... 1
Setting Bandwidth.........................................................................9
General Description ......................................................................... 1
Temperature Output and Calibration.........................................9
Functional Block Diagram .............................................................. 1
Calibrated Performance................................................................9
Revision History ............................................................................... 2
ADXRS614 and Supply Ratiometricity ......................................9
Specifications..................................................................................... 3
Null Adjustment ......................................................................... 10
Absolute Maximum Ratings............................................................ 4
Self-Test Function ...................................................................... 10
Rate Sensitive Axis ....................................................................... 4
Continuous Self-Test.................................................................. 10
ESD Caution.................................................................................. 4
Outline Dimensions ....................................................................... 11
Pin Configuration and Function Descriptions............................. 5
Ordering Guide .......................................................................... 11
Typical Performance Characteristics ............................................. 6
REVISION HISTORY
4/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 12
ADXRS614
SPECIFICATIONS
All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed.
@TA = −40°C to +105°C, VS = AVCC = VDD = 5 V, VRATIO = AVCC, angular rate = 0°/s, bandwidth = 80 Hz (COUT = 0.01 μF),
IOUT = 100 μA, ±1 g, unless otherwise noted.
Table 1.
Parameter
SENSITIVITY (Ratiometric) 1
Measurement Range 2
Initial and Over Temperature
Temperature Drift 3
Nonlinearity
NULL (Ratiometric)1
Null
Linear Acceleration Effect
NOISE PERFORMANCE
Rate Noise Density
FREQUENCY RESPONSE
Bandwidth 4
Sensor Resonant Frequency
SELF-TEST (Ratiometric)1
ST1 RATEOUT Response
ST2 RATEOUT Response
Logic 1 Input Voltage
Logic 0 Input Voltage
Input Impedance
TEMPERATURE SENSOR (Ratiometric)1
VOUT at 25°C
Scale Factor 5
Load to VS
Load to Common
TURN-ON TIME
OUTPUT DRIVE CAPABILITY
Current Drive
Capacitive Load Drive
POWER SUPPLY
Operating Voltage (VS)
VRATIO Input
Supply Current
TEMPERATURE RANGE
Specified Performance
Conditions
Clockwise rotation is positive output
Full-scale range over specifications range
Min
ADXRS614BBGZ
Typ
Max
±50
22.5
Unit
Best fit straight line
±75
25
±3
0.1
−40°C to +105°C
Any axis
2.5
0.1
V
°/sec/g
TA = 25°C
0.04
°/sec/√Hz
1
27.5
1000
14.5
ST1 pin from Logic 0 to Logic 1
ST2 pin from Logic 0 to Logic 1
−1.9
1.9
0.8 × VRATIO
0.2 × VRATIO
To common
50
Load = 100 MΩ
@25°C, VRATIO = 5 V
2.35
V
V
V
V
kΩ
Power on to ±½°/sec of final
50
For rated specifications
200
1000
μA
pF
5.25
VS
5.0
V
V
mA
+105
°C
5.00
3.5
–40
1
2.65
Hz
kHz
V
mV/°C
kΩ
kΩ
ms
4.75
3
2.5
9
25
25
°/sec
mV/°/sec
%
% of FS
Parameter is linearly ratiometric with VRATIO.
The maximum range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies.
From +25°C to −40°C or from +25°C to +105°C.
4
Adjusted by external capacitor, COUT.
5
For a change in temperature from 25°C to 26°C. VTEMP is ratiometric to VRATIO. See the Temperature Output and Calibration section for more details.
2
3
Rev. 0 | Page 3 of 12
ADXRS614
ABSOLUTE MAXIMUM RATINGS
RATE SENSITIVE AXIS
Parameter
Acceleration (Any Axis, 0.5 ms)
Unpowered,
Powered
VDD, AVCC
VRATIO
Output Short-Circuit Duration
(Any Pin to Common)
Operating Temperature Range
Storage Temperature
Rating
2000 g
2000 g
–0.3 V to +6.0 V
AVCC
Indefinite
–55°C to +125°C
–65°C to +150°C
Stresses above those listed under the Absolute Maximum
Ratings may cause permanent damage to the device. This is a
stress rating only; functional operation of the device at these or
any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
The ADXRS614 is a Z-axis rate-sensing device (also called a
yaw rate sensing device). It produces a positive going output
voltage for clockwise rotation about the axis normal to the
package top, that is, clockwise when looking down at the
package lid.
RATE
AXIS
RATE OUT
VCC = 5V
LONGITUDINAL
AXIS
4.75V
+
VRATIO/2
7
RATE IN
A1
ABCDE FG
1
LATERAL AXIS
0.25V
GND
Figure 2. RATEOUT Signal Increases with Clockwise Rotation
ESD CAUTION
Drops onto hard surfaces can cause shocks of greater than
2000 g and can exceed the absolute maximum rating of the
device. Exercise care during handling to avoid damage.
Rev. 0 | Page 4 of 12
06748-002
Table 2.
ADXRS614
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
VDD
PGND
CP5
CP3
CP4
7
6
ST1
CP1
5
ST2
CP2
4
AVCC
3
TEMP
2
AGND
`
G
F
VRATIO
NC
SUMJ
E
D
C
RATEOUT
B
A
06748-003
1
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No.
6D, 7D
6A, 7B
6C, 7C
5A, 5B
4A, 4B
3A, 3B
1B, 2A
1C, 2C
1D, 2D
1E, 2E
1F, 2G
3F, 3G
4F, 4G
5F, 5G
6G, 7F
6E, 7E
Mnemonic
CP5
CP4
CP3
CP1
CP2
AVCC
RATEOUT
SUMJ
NC
VRATIO
AGND
TEMP
ST2
ST1
PGND
VDD
Description
HV Filter Capacitor (0.1 nF).
Charge Pump Capacitor (22 nF).
Charge Pump Capacitor (22 nF).
Charge Pump Capacitor (22 nF).
Charge Pump Capacitor (22 nF).
Positive Analog Supply.
Rate Signal Output.
Output Amp Summing Junction.
No Connect.
Reference Supply for Ratiometric Output.
Analog Supply Return.
Temperature Voltage Output.
Self-Test for Sensor 2.
Self-Test for Sensor 1.
Charge Pump Supply Return.
Positive Charge Pump Supply.
Rev. 0 | Page 5 of 12
ADXRS614
TYPICAL PERFORMANCE CHARACTERISTICS
N > 1000 for all typical performance plots, unless otherwise noted.
18
35
16
30
% OF POPULATION
% OF POPULATION
14
12
10
8
6
25
20
15
10
4
VOLTS
06748-007
0
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
0
5
06748-004
2
–10–9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10
DRIFT (%)
Figure 4. Null Output at 25°C (VRATIO = 5 V)
Figure 7. Sensitivity Drift over Temperature
30
40
35
25
% OF POPULATION
% OF POPULATION
30
20
15
10
25
20
15
10
5
–0.6 –0.5 –0.4 –0.3 –0.2 –0.1
0
0.1
0.2
0.3
0.4
0.5
0
0.6
º/s/ºC
06748-008
06748-005
0
5
–2.5 –2.4 –2.3 –2.2 –2.1 –2 –1.9 –1.8 –1.7 –1.6 –1.5 –1.4 –1.3
VOLTS
Figure 5. Null Drift over Temperature (VRATIO = 5 V)
Figure 8. ST1 Output Change at 25°C (VRATIO = 5 V)
50
40
45
35
40
% OF POPULATION
30
25
20
15
25
20
15
10
10
0
22 22.5 23 23.5 24 24.5 25 25.5 26 26.5 27 27.5 28
mV/º/s
06748-009
5
0
5
06748-006
% OF POPULATION
30
35
1.3 1.4 1.5 1.6 1.7 1.8 1.9
2
2.1 2.2 2.3 2.4 2.5
VOLTS
Figure 6. Sensitivity at 25°C (VRATIO = 5 V)
Figure 9. ST2 Output Change at 25°C (VRATIO = 5 V)
Rev. 0 | Page 6 of 12
14
40
12
35
30
10
% OF POPULATION
8
6
4
20
15
10
5
06748-010
2
0
25
50
54
58
62
66
70
74
78
82
86
90
94
0
98
2.40 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 2.58 2.60
º/s
VOLTS
Figure 10 .Measurement Range
06748-013
% OF POPULATION
ADXRS614
Figure 13. VTEMP Output at 25°C (VRATIO = 5 V)
2.5
3.3
2
3.1
1.5
2.9
1
2.7
VOLTS
0
–0.5
2.5
2.3
2.1
–1
1.9
–1.5
–20
0
20
40
60
80
100
256 PARTS
1.5
–40
120
–20
0
20
40
60
80
100
120
06748-014
–2.5
–40
1.7
06748-011
–2
850
06748-015
VOLTS
0.5
TEMPERATURE (°C)
TEMPERATURE (ºC)
Figure 14. VTEMP Output over Temperature (VRATIO = 5 V)
Figure 11. Typical Self-Test Change over Temperature
30
60
REF
50
25
Y
X
+45°
–45°
g OR °/s
30
15
20
10
10
0
5
06748-012
0
–10
–20
750
2.5
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
4.0
4.1
4.2
4.3
4.4
4.5
% OF POPULATION
40
20
(mA)
770
790
810
830
TIME (ms)
Figure 12. Current Consumption at 25°C (VRATIO = 5 V)
Figure 15. g and g × g Sensitivity for a 50 g, 10 ms Pulse
Rev. 0 | Page 7 of 12
ADXRS614
1.6
0.10
1.4
1.2
0.05
(°/s)
(°/s)
1.0
0.8
0
0.6
–0.05
0.4
LAT
LONG
0.2
(Hz)
–0.10
06748-016
10k
1k
0
20
40
60
80
100
120
140
TIME (Hours)
06748-019
RATE
0
100
Figure 19. Typical Shift in 90 sec Null Averages Accumulated
over 140 Hours
Figure 16. Typical Response to 10 g Sinusoidal Vibration
(Sensor Bandwidth = 2 kHz)
400
0.10
300
DUT1 OFFSET BY +200°/s
200
0.05
(°/s)
(°/s)
100
0
0
–100
DUT2 OFFSET BY –200°/s
–200
–0.05
0
50
100
150
200
250
(ms)
–0.10
06748-017
–400
0
600
1200
1800
2400
3000
3600
TIME (Seconds)
Figure 17. Typical High g (2500 g) Shock Response
(Sensor Bandwidth = 40 Hz)
06748-020
–300
Figure 20. Typical Shift in Short Term Null (Bandwidth = 1 Hz)
0.1
0.1
0.01
(°/s rms)
(°/s/ Hz rms)
1
0.01
1
10
100
1k
10k
100k
AVERAGE TIME (Seconds)
Figure 18. Typical Root Allan Deviation at 25°C vs. Averaging Time
0.0001
10
100
1k
10k
100k
(Hz)
Figure 21. Typical Noise Spectral Density (Bandwidth = 40 Hz)
Rev. 0 | Page 8 of 12
06748-021
0.1
06748-018
0.001
0.01
0.001
ADXRS614
THEORY OF OPERATION
0.1
0.01
(°/s/ Hz rms)
0.001
0.0001
0.00001
0.000001
10
100
10k
1k
100k
(Hz)
The electrostatic resonator requires 18 V to 20 V for operation.
Because only 5 V are typically available in most applications, a
charge pump is included on-chip. If an external 18 V to 20 V
supply is available, the two capacitors on CP1 through CP4 can
be omitted and this supply can be connected to CP5 (Pin 6D,
Pin 7D). Note that CP5 should not be grounded when power is
applied to the ADXRS614. Although no damage occurs, under
certain conditions the charge pump may fail to start up after the
ground is removed without first removing power from the
ADXRS614.
SETTING BANDWIDTH
Figure 22. Noise Spectral Density with Additional 250 Hz Filter
TEMPERATURE OUTPUT AND CALIBRATION
It is common practice to temperature-calibrate gyros to
improve their overall accuracy. The ADXRS614 has a
temperature proportional voltage output that provides input to
such a calibration method. The temperature sensor structure is
shown in Figure 23. The temperature output is characteristically
nonlinear, and any load resistance connected to the TEMP
output results in decreasing the TEMP output and temperature
coefficient. Therefore, buffering the output is recommended.
The voltage at the TEMP pin (3F, 3G) is nominally 2.5 V at
25°C and VRATIO = 5 V. The temperature coefficient is ~9 mV/°C
at 25°C. Although the TEMP output is highly repeatable, it has
only modest absolute accuracy.
1
(2 × π × ROUT × COUT )
VTEMP
VRATIO
and can be well controlled because ROUT has been trimmed
during manufacturing to be 200 kΩ ±1%. Any external resistor
applied between the RATEOUT pin (1B, 2A) and SUMJ pin
(1C, 2C) results in:
(200 kΩ × R EXT )
ROUT =
(200 kΩ + R EXT )
In general, an additional hardware or software filter is added to
attenuate high frequency noise arising from demodulation
spikes at the gyro’s 14 kHz resonant frequency (the noise spikes
at 14 kHz can be clearly seen in the power spectral density
curve shown in Figure 21). Typically, this additional filter’s
corner frequency is set to greater than 5× the required
bandwidth to preserve good phase response.
Figure 22 shows the effect of adding a 250 Hz filter to the
output of an ADXRS614 set to 40 Hz bandwidth (as shown in
Figure 21). High frequency demodulation artifacts are
attenuated by approximately 18 dB.
RFIXED
RTEMP
06748-023
External Capacitor COUT is used in combination with the onchip ROUT resistor to create a low-pass filter to limit the
bandwidth of the ADXRS614 rate response. The –3 dB
frequency set by ROUT and COUT is:
f OUT =
06748-022
The ADXRS614 operates on the principle of a resonator gyro.
Two polysilicon sensing structures each contain a dither frame
that is electrostatically driven to resonance, producing the
necessary velocity element to produce a Coriolis force during
angular rate. At two of the outer extremes of each frame,
orthogonal to the dither motion, are movable fingers that are
placed between fixed pickoff fingers to form a capacitive pickoff
structure that senses Coriolis motion. The resulting signal is fed
to a series of gain and demodulation stages that produce the
electrical rate signal output. The dual-sensor design rejects
external g-forces and vibration. Fabricating the sensor with the
signal conditioning electronics preserves signal integrity in
noisy environments.
Figure 23. ADXRS614 Temperature Sensor Structure
CALIBRATED PERFORMANCE
Using a 3-point calibration technique, it is possible to calibrate
the null and sensitivity drift of the ADXRS614 to an overall
accuracy of nearly 200°/hour. An overall accuracy of 40°/hour
or better is possible using more points.
Limiting the bandwidth of the device reduces the flat-band
noise during the calibration process, improving the
measurement accuracy at each calibration point.
ADXRS614 AND SUPPLY RATIOMETRICITY
The ADXRS614 RATEOUT and TEMP signals are ratiometric
to the VRATIO voltage, that is, the null voltage, rate sensitivity, and
temperature outputs are proportional to VRATIO. Thus, the
ADXRS614 is most easily used with a supply-ratiometric ADC
that results in self-cancellation of errors due to minor supply
variations. There is some small error due to nonratiometric
Rev. 0 | Page 9 of 12
ADXRS614
behavior. Typical ratiometricity error for null, sensitivity, selftest, and temperature output is outlined in Table 3.
Note that VRATIO must never be greater than AVCC.
Table 3. Ratiometricity Error for Various Parameters
Parameter
ST1
Mean
Sigma
ST2
Mean
Sigma
Null
Mean
Sigma
Sensitivity
Mean
Sigma
VTEMP
Mean
Sigma
VS = VRATIO = 4.75 V
VS = VRATIO = 5.25 V
−0.4%
0.6%
−0.3%
0.6%
−0.4%
0.6%
−0.3%
0.6%
−0.04%
0.3%
−0.02%
0.2%
0.03%
0.1%
0.1%
0.1%
−0.3%
0.1%
−0.5%
0.1%
SELF-TEST FUNCTION
The ADXRS614 includes a self-test feature that actuates each of
the sensing structures and associated electronics as if subjected
to angular rate. It is activated by standard logic high levels
applied to Input ST1 (5F, 5G), Input ST2 (4F, 4G), or both. ST1
causes the voltage at RATEOUT to change about −1.9 V, and
ST2 causes an opposite change of +1.9 V. The self-test response
follows the viscosity temperature dependence of the package
atmosphere, approximately 0.25%/°C.
Activating both ST1 and ST2 simultaneously is not damaging.
ST1 and ST2 are fairly closely matched (±5%), but actuating
both simultaneously may result in a small apparent null bias
shift proportional to the degree of self-test mismatch.
ST1 and ST2 are activated by applying a voltage of greater than
0.8 × VRATIO to the ST1 and ST2 pins. ST1 and ST2 are
deactivated by applying a voltage of less than 0.2 × VRATIO to the
ST1 pin and the ST2 pin. The voltage applied to ST1 and ST2
must never be greater than AVCC.
CONTINUOUS SELF-TEST
NULL ADJUSTMENT
The nominal 2.5 V null is for a symmetrical swing range at
RATEOUT (1B, 2A). However, a nonsymmetrical output swing
may be suitable in some applications. Null adjustment is
possible by injecting a suitable current to SUMJ (1C, 2C). Note
that supply disturbances may reflect some null instability.
Digital supply noise should be avoided particularly in this case.
The one-chip integration of the ADXRS614 gives it higher
reliability than is obtainable with any other high volume
manufacturing method. In addition, it is manufactured under a
mature BiMOS process with field-proven reliability. As an
additional failure detection measure, a power-on self-test can be
performed. However, some applications may warrant
continuous self-test while sensing rate. Details outlining
continuous self-test techniques are also available in a separate
application note.
Rev. 0 | Page 10 of 12
ADXRS614
OUTLINE DIMENSIONS
*A1 CORNER
INDEX AREA
7.05
6.85 SQ
6.70
7
6
5
4
3
2
A
A1 BALL PAD
INDICATOR
TOP VIEW
1
B
4.80
BSC SQ
C
BOTTOM
VIEW
D
E
F
G
0.80 BSC
(BALL PITCH)
DETAIL A
3.80 MAX
SEATING
PLANE
0.60
0.55
0.50
BALL DIAMETER
3.30 MAX
2.50 MIN
COPLANARITY
0.15
*BALL A1 IDENTIFIER IS GOLD PLATED AND CONNECTED
TO THE D/A PAD INTERNALLY VIA HOLES.
060506-A
DETAIL A
0.60
0.25
Figure 24. 32-Lead Ceramic Ball Grid Array [CBGA]
(BG-32-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model
ADXRS614BBGZ1
ADXRS614BBGZ-RL1
EVAL-ADXRS614Z1
Temperature Range
–40°C to +105°C
–40°C to +105°C
Package Description
32-Lead Ceramic Ball Grid Array (CBGA)
32-Lead Ceramic Ball Grid Array (CBGA)
Evaluation Board
1
Z = RoHS Compliant Part.
Rev. 0 | Page 11 of 12
Package Option
BG-32-3
BG-32-3
ADXRS614
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06748-0-4/07(0)
Rev. 0 | Page 12 of 12