DATASHEET SEARCH SITE | WWW.ALLDATASHEET.COM
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 12
Technical content
High Stability, Low Noise Vibration Rejecting Yaw Rate Gyroscope Data Sheet ADXRS646 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. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2011 Analog Devices, Inc. All rights reserved.
FEATURES
12°/hr bias stability Z-axis (yaw rate) response 0.01°/√sec angle random walk High vibration rejection over wide frequency Measurement range extendable to a maximum of ±450°/sec 10,000 g powered shock survivability Ratiometric to referenced supply
6 V single-supply operation
−40°C to +105°C operation Self-test on digital command Ultrasmall and light (<0.15 cc, <0.5 gram) Temperature sensor output Complete rate gyroscope on a single chip RoHS compliant
APPLICATIONS
Severe mechanical environments Platform stabilization GENERAL DESCRIPTION The ADXRS646 is a high performance angular rate sensor (gyroscope) that offers excellent vibration immunity. Bias stability is a widely-recognized figure of merit for high performance gyroscopes, but in real-world applications, vibration sensitivity is often a more significant performance limitation and should be considered in gyroscope selection. The ADXRS646 offers superior vibration immunity and acceleration rejection as well as a low bias drift of 12°/hr (typical), enabling it to offer rate sensing in harsh environments where shock and vibration are present. The ADXRS646 is manufactured using the Analog Devices, Inc., patented high volume BiMOS surface-micromachining process. An advanced, differential, quad sensor design provides the improved acceleration and vibration rejection. The output signal, RATEOUT, is a voltage proportional to angular rate about the axis normal to the top surface of the package. The measurement range is a minimum of ±250°/sec. The output is ratiometric with respect to a provided reference supply. Other external capacitors are required for operation. 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 condi- tioning circuits. The ADXRS646 is available in a 7 mm × 7 mm × 3 mm CBGA chip-scale package. FUNCTIONAL BLOCK DIAGRAM Figure 1. VDD AGND PGND AVCC ST2 ST1 TEMP VRATIO ROUT CP1 CP2 CP3 CP4 CP5 SUMJ RATEOUT DEMOD 180kΩ ±1% 22nF 100nF 22nF 100nF 100nF 100nF DRIVE AMP MECHANICAL SENSOR CHARGE PUMP AND VOLTAGE REGULATOR COUT 3V TO 6V (ADC REF) AC AMP VGA 25kΩ @ 25°C ADXRS646 25kΩSELF-TEST 09771-001
Rev. 0 | Page 2 of 12 TABLE OF CONTENTS
REVISION HISTORY
9/11—Revision 0: Initial Version
Rev. 0 | Page 3 of 12 SPECIFICATIONS All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. TA = 25°C, VS = AVCC = VDD = 6 V, VRATIO = AVCC, angular rate = 0°/sec, bandwidth = 80 Hz (COUT = 0.01 µF), IOUT = 100 µA, ±1 g, unless otherwise noted. Table 1. Parameter Test Conditions/Comments Min Typ Max Unit SENSITIVITY1 Clockwise rotation is positive output Measurement Range2 Full-scale range over specifications range ±250 ±300 °/sec Initial 8.5 9 9.5 mV/°/sec Temperature Drift3 ±3 % Nonlinearity Best fit straight line 0.01 % of FS NULL1 Null −40°C to +105°C 2.7 3.0 3.3 V Calibrated Null4 −40°C to +105°C ±0.1 °/sec Temperature Drift3 ±3 °/sec Linear Acceleration Effect Any axis 0.015 °/sec/g Vibration Rectification 25 g rms, 50 Hz to 5 kHz 0.0001 °/sec/g2 NOISE PERFORMANCE Rate Noise Density TA ≤ 25°C 0.01 °/sec/√Hz Rate Noise Density TA ≤ 105°C 0.015 °/sec/√Hz Resolution Floor TA = 25°C, 1 minute to 1 hour in-run 12 °/hr FREQUENCY RESPONSE Bandwidth5 ±3 dB user adjustable up to specification 1000 Hz Sensor Resonant Frequency 15.5 17.5 20 kHz SELF-TEST1 ST1 RATEOUT Response ST1 pin from Logic 0 to Logic 1 −50 °/sec ST2 RATEOUT Response ST2 pin from Logic 0 to Logic 1 50 °/sec ST1 to ST2 Mismatch6 −5 ±0.5 +5 % Logic 1 Input Voltage ST1 pin or ST2 pin 4 V Logic 0 Input Voltage 2 V Input Impedance ST1 pin or ST2 pin to common 40 50 100 kΩ TEMPERATURE SENSOR1 VOUT at 25°C Load = 10 MΩ 2.8 2.9 3.0 V Scale Factor4 25°C, VRATIO = 6 V 10 mV/°C Load to VS 25 kΩ Load to Common 25 kΩ TURN-ON TIME4 Power on to ±0.5°/sec of final with CP5 = 100 nF 50 ms OUTPUT DRIVE CAPABILITY Current Drive For rated specifications 200 µA Capacitive Load Drive 1000 pF POWER SUPPLY Operating Voltage (VS) 5.75 6.00 6.25 V Quiescent Supply Current 4 mA TEMPERATURE RANGE Specified Performance −40 +105 °C 1 Parameter is linearly ratiometric with VRATIO. 2 Measurement range is the maximum range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies. 3 From +25°C to −40°C or +25°C to +105°C. 4 Based on characterization. 5 Adjusted by external capacitor, COUT. Reducing bandwidth below 0.01 Hz does not result in further noise improvement. 6 Self-test mismatch is described as (ST2 + ST1)/((ST2 − ST1)/2).
device. Care should be exercised in handling to avoid damage. top, that is, clockwise when looking down at the package lid. Figure 2. RATEOUT Signal Increases with Clockwise Rotation
Figure 3. Pin Configuration Table 3. Pin Function Descriptions 6D, 7D CP5 HV Filter Capacitor, 100nF (±5%). 6A, 7B CP4 Charge Pump Capacitor, 22 nF (±5%). 6C, 7C CP3 Charge Pump Capacitor, 22 nF (±5%). 5A, 5B CP1 Charge Pump Capacitor, 22 nF (±5%). 4A, 4B CP2 Charge Pump Capacitor, 22 nF (±5%). 3A, 3B AVCC Positive Analog Supply. 1B, 2A RATEOUT Rate Signal Output. 1C, 2C SUMJ Output Amp Summing Junction. 1D, 2D DNC Do Not Connect to this Pin. 1E, 2E VRATIO Reference Supply for Ratiometric Output. 1F, 2G AGND Analog Supply Return. 3F, 3G TEMP Temperature Voltage Output. 4F, 4G ST2 Self-Test for Sensor 2. 5F, 5G ST1 Self-Test for Sensor 1. 6G, 7F PGND Charge Pump Supply Return. 6E, 7E VDD Positive Charge Pump Supply.
- DNC = DO NOT CONNECT TO THIS PIN.
Rev. 0 | Page 10 of 12 SUPPLY RATIOMETRICITY The null output voltage (RATEOUT), sensitivity, self-test responses (ST1 and ST2), and temperature output (TEMP) of the ADXRS646 are ratiometric to VRATIO. Therefore, using the ADXRS646 with a supply-ratiometric ADC results in self- cancellation of errors resulting from minor supply variations. There remains a small, usually negligible, error due to non- ratiometric behavior. Note that, to guarantee full measurement range, VRATIO should not be greater than AVCC. NULL ADJUSTMENT The nominal 3.0 V null output voltage is true for a symmetrical swing range at RATEOUT (1B, 2A). However, an asymmetric output swing may be suitable in some applications. Null adjust- ment is possible by injecting a suitable current to SUMJ (1C, 2C). Note that supply disturbances may cause some null instability. Digital supply noise should be avoided, particularly in this case. SELF-TEST FUNCTION The ADXRS646 includes a self-test feature that actuates each of the sensing structures and associated electronics in the same manner as if the gyroscope were subjected to angular rate. Self-test is activated by applying the standard logic high level ST1 pin (5F, 5G), the ST2 pin (4F, 4G), or both. Applying a logic high to Pin ST1 causes the voltage at RATEOUT to change by −450 mV (typical), and applying a logic high to Pin ST2 causes an opposite change of +450 mV (typical). The voltage applied to the ST1 and ST2 pins must never be greater than AVCC. The self-test response follows the temperature dependence of the viscosity of the package atmosphere, approximately 0.25%/°C. Activating both ST1 and ST2 simultaneously is not damaging. The output responses generated by ST1 and ST2 are closely matched (±2%), but actuating both simultaneously may result in a small apparent null bias shift proportional to the degree of self-test mismatch. CONTINUOUS SELF-TEST The on-chip integration of the ADXRS646, as well as the mature process with which it is manufactured, have provided the gyroscope with field-proven reliability. As an additional failure detection measure, self-test can be performed at power-up or occasionally during operation. However, some applications may require continuous self-test while sensing rotation rate. Details outlining continuous self-test techniques are available in the AN-768 Application Note, Using the ADXRS150/ADXRS300 in Continuous Self-Test Mode. Although the title of this application note refers to other Analog Devices gyroscopes, the techniques apply equally to the ADXRS646. MODIFYING THE MEASUREMENT RANGE The ADXRS646 scale factor can be reduced to extend the measurement range to as much as ±450°/sec by adding a single 225 kΩ resistor between RATEOUT and SUMJ. If an external resistor is added between RATEOUT and SUMJ, COUT must be proportionally increased to maintain correct bandwidth.
Figure 23. 32-Lead Ceramic Ball Grid Array [CBGA]
0.60 MAX
0.25 MIN
3.20 MAX
2.50 MIN
TO THE D/A PAD INTERNALLY VIA HOLES.
3.80 MAX
registered trademarks are the property of their respective owners.