±300°/s Single Chip Yaw Rate Gyro with Signal Conditioning ADXRS300 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 Self-test on digital command Temperature sensor output Precision voltage reference output Absolute rate output for precision applications 5 V single-supply operation Ultrasmall and light (< 0.15 cc, < 0.5 gram) The ADXRS300 is a complete angular rate sensor (gyroscope) that uses Analog Devices’ surface-micromachining process to make a functionally complete and low cost angular rate sensor integrated with all of the 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 (see Figure 4). A single external resistor can be used to lower the scale factor. An external capacitor is used to set the bandwidth. Other external capacitors are required for operation (see Figure 5). APPLICATIONS Vehicle chassis rollover sensing Inertial measurement units Platform stabilization A precision reference and a temperature output are also provided for compensation techniques. Two digital self-test inputs electromechanically excite the sensor to test proper operation of both sensors and the signal conditioning circuits. The ADXRS300 is available in a 7 mm × 7 mm × 3 mm BGA chip-scale package. FUNCTIONAL BLOCK DIAGRAM + 5V – 100nF AVCC 3A ST1 5G ST2 4G COUT 100nF SELF TEST SUMJ 1C CMID AGND 2G 1F 1D ROUT CORIOLIS SIGNAL CHANNEL 180kΩ 1% RSEN2 RSEN1 π DEMOD RATE SENSOR ≈7kΩ ±35% ≈7kΩ ±35% 1B RATEOUT RESONATOR LOOP 2A 1E 2.5V REF 2.5V PTAT 3G TEMP 12V CHARGE PUMP/REG. PDD 4A 5A CP2 22nF ADXRS300 7E 6G 7F PGND CP1 6A 7B CP4 7C CP3 7D CP5 47nF 100nF 22nF Figure 1. Rev. B 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: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved. ADXRS300 TABLE OF CONTENTS Specifications..................................................................................... 3 Increasing Measurement Range ..................................................7 Absolute Maximum Ratings............................................................ 4 Using the ADXRS300 with a Supply-Ratiometric ADC ..........7 Rate Sensitive Axis........................................................................ 4 Null Adjust .....................................................................................7 ESD Caution.................................................................................. 4 Self-Test Function .........................................................................7 Pin Configuration and Function Descriptions............................. 5 Continuous Self-Test.....................................................................7 Theory of Operation ........................................................................ 6 Outline Dimensions ..........................................................................8 Supply and Common Considerations ....................................... 6 Ordering Guide .............................................................................8 Setting Bandwidth ........................................................................ 7 REVISION HISTORY 3/04—Data Sheet Changed from Rev. A to Rev. B Updated Format..................................................................Universal Changes to Table 1 Conditions ....................................................... 3 Added Evaluation Board to Ordering Guide ................................ 8 3/03—Data Sheet Changed from Rev. 0 to Rev. A Edit to Figure 3.................................................................................. 5 Rev. B | Page 2 of 8 ADXRS300 SPECIFICATIONS @TA = 25°C, VS = 5 V, Angular Rate = 0°/s, Bandwidth = 80 Hz (COUT = 0.01 µF), ±1g, unless otherwise noted. Table 1. Parameter SENSITIVITY Dynamic Range2 Initial Over Temperature3 Nonlinearity NULL Initial Null Over Temperature3 Turn-On Time Linear Acceleration Effect Voltage Sensitivity NOISE PERFORMANCE Rate Noise Density FREQUENCY RESPONSE 3 dB Bandwidth (User Selectable)4 Sensor Resonant Frequency SELF-TEST INPUTS ST1 RATEOUT Response5 ST2 RATEOUT Response5 Logic 1 Input Voltage Logic 0 Input Voltage Input Impedance TEMPERATURE SENSOR VOUT at 298°K Max Current Load on Pin Scale Factor OUTPUT DRIVE CAPABILITY Output Voltage Swing Capacitive Load Drive 2.5 V REFERENCE Voltage Value Load Drive to Ground Load Regulation Power Supply Rejection Temperature Drift POWER SUPPLY Operating Voltage Range Quiescent Supply Current TEMPERATURE RANGE Specified Performance Grade A Conditions Clockwise rotation is positive output Full-scale range over specifications range @25°C VS = 4.75 V to 5.25 V Best fit straight line Min1 ±300 4.6 4.6 5 5 0.1 5.4 5.4 2.50 2.7 2.7 Unit °/s mV/°/s mV/°/s % of FS 35 0.2 1 V V ms °/s/g °/s/V @25°C 0.1 °/s/√Hz 22 nF as comp cap (see the Setting Bandwidth section) 40 14 Hz kHz VS = 4.75 V to 5.25 V Power on to ±½°/s of final Any axis VCC = 4.75 V to 5.25 V ST1 pin from Logic 0 to 1 ST2 pin from Logic 0 to 1 Standard high logic level definition Standard low logic level definition To common 2.3 2.3 ADXRS300ABG Typ Max1 –150 +150 3.3 –270 +270 –450 +450 1.7 50 2.50 Source to common Proportional to absolute temperature IOUT = ±100 µA 50 8.4 0.25 1000 1 V µA mV/°K VS – 0.25 V pF 2.45 2.5 200 5.0 1.0 5.0 2.55 V µA mV/mA mV/V mV 4.75 5.00 6.0 5.25 8.0 V mA +85 °C Source 0 < IOUT < 200 µA 4.75 VS to 5.25 VS Delta from 25°C Temperature tested to max and min specifications mV mV V V kΩ –40 All minimum and maximum specifications are guaranteed. Typical specifications are not tested or guaranteed. Dynamic range is the maximum full-scale measurement range possible, including output swing range, initial offset, sensitivity, offset drift, and sensitivity drift at 5 V supplies. 3 Specification refers to the maximum extent of this parameter as a worst-case value of TMIN or TMAX. 4 Frequency at which response is 3 dB down from dc response with specified compensation capacitor value. Internal pole forming resistor is 180 kΩ. See the Setting Bandwidth section. 5 Self-test response varies with temperature. See the Self-Test Function section for details. 2 Rev. B | Page 3 of 8 ADXRS300 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Acceleration (Any Axis, Unpowered, 0.5 ms) Acceleration (Any Axis, Powered, 0.5 ms) +VS Output Short-Circuit Duration (Any Pin to Common) Operating Temperature Range Storage Temperature RATE SENSITIVE AXIS Rating 2000 g 2000 g –0.3 V to +6.0 V Indefininte This is a Z-axis rate-sensing device that is 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, i.e., clockwise when looking down at the package lid. –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. RATEOUT RATE AXIS VCC = 5V LONGITUDINAL AXIS 4.75V 2.5V 7 A1 ABCDEFG LATERAL AXIS RATE IN 1 0.25V GND Figure 2. RATEOUT Signal Increases with Clockwise Rotation Applications requiring more than 200 cycles to MIL-STD-883 Method 1010 Condition B (–55°C to +125°C) require underfill or other means to achieve this requirement. Drops onto hard surfaces can cause shocks of greater than 2000 g and exceed the absolute maximum rating of the device. Care should be exercised in handling to avoid damage. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. B | Page 4 of 8 ADXRS300 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS PGND PDD CP5 CP3 CP4 7 6 ST1 CP1 5 ST2 CP2 4 AVCC 3 TEMP 2 1 AGND G F 2.5V CMID E D RATEOUT SUMJ C B A Figure 3. 32-Lead BGA (Bottom View) Table 3. 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 CMID 2.5V AGND TEMP ST2 ST1 PGND PDD Description HV Filter Capacitor—47 nF Charge Pump Capacitor—22 nF Charge Pump Capacitor—22 nF Charge Pump Capacitor—22 nF Charge Pump Capacitor—22 nF + Analog Supply Rate Signal Output Output Amp Summing Junction HF Filter Capacitor—100 nF 2.5 V Precision Reference Analog Supply Return Temperature Voltage Output Self-Test for Sensor 2 Self-Test for Sensor 1 Charge Pump Supply Return + Charge Pump Supply Rev. B | Page 5 of 8 ADXRS300 THEORY OF OPERATION The ADXRS300 operates on the principle of a resonator gyro. Two polysilicon sensing structures each contain a dither frame, which is electrostatically driven to resonance. This produces 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. The electrostatic resonator requires 14 V to 16 V for operation. Since only 5 V is typically available in most applications, a charge pump is included on-chip. If an external 14 V to 16 V supply is available, the two capacitors on CP1–CP4 can be omitted and this supply can be connected to CP5 (Pin 7D) with a 100 nF decoupling capacitor in place of the 47 nF. After the demodulation stage, there is a single-pole low-pass filter consisting of an internal 7 kΩ resistor (RSEN1) and an external user-supplied capacitor (CMID). A CMID capacitor of 100 nF sets a 400 Hz ±3 5% low-pass pole and is used to limit high frequency artifacts before final amplification. The bandwidth limit capacitor, COUT, sets the pass bandwidth (see Figure 5 and the Setting Bandwidth section). SUPPLY AND COMMON CONSIDERATIONS Only power supplies used for supplying analog circuits are recommended for powering the ADXRS300. High frequency noise and transients associated with digital circuit supplies may have adverse effects on device operation. Figure 4 shows the recommended connections for the ADXRS300 where both AVCC and PDD have a separate decoupling capacitor. These should be placed as close to the their respective pins as possible before routing to the system analog supply. This minimizes the noise injected by the charge pump that uses the PDD supply. It is also recommended to place the charge pump capacitors connected to the CP1–CP4 pins as close to the part as possible. These capacitors are used to produce the on-chip high voltage supply switched at the dither frequency at approximately 14 kHz. Care should be taken to ensure that there is no more than 50 pF of stray capacitance between CP1–CP4 and ground. Surface-mount chip capacitors are suitable as long as they are rated for over 15 V. + 5V – AGND AVCC 2G 3A ST1 5G SELF ST2 4G TEST CMID 1F SUMJ 1D 1C ROUT 180kΩ 1% CORIOLIS SIGNAL CHANNEL RSEN1 π RSEN2 DEMOD RATE SENSOR 1B ≈7kΩ ±35% 100nF 22nF COUT 100nF 100nF RATE2A OUT RESONATOR LOOP 1E 2.5V 2.5V REF CP3 CP5 CP4 PDD PGND PTAT 3G TEMP 7B 7C 7D 7E PDD 6G 6A 4A 5A 47nF CP1 CP2 5G 5A 5V 6G 7F 4G ST2 3G TEMP 6A 7B 7C 7D CP4 CP3 CP5 PGND ADXRS300 4A 7E CP1 ST1 22nF CP2 12V CHARGE PUMP/REG. 7F 22nF 47nF 22nF 100nF 3A AVCC 100nF 2G 2A 1B 1C RATEOUT SUMJ 1D 1E CMID 2.5V 1F AGND 100nF COUT = 22nF NOTE THAT INNER ROWS/COLUMNS OF PINS HAVE BEEN OMITTED FOR CLARITY BUT SHOULD BE CONNECTED IN THE APPLICATION. Figure 4. Example Application Circuit (Top View) Rev. B | Page 6 of 8 Figure 5. Block Diagram with External Components ADXRS300 SETTING BANDWIDTH NULL ADJUST External capacitors CMID and COUT are used in combination with on-chip resistors to create two low-pass filters to limit the bandwidth of the ADXRS300’s rate response. The –3 dB frequency set by ROUT and COUT is Null adjustment is possible by injecting a suitable current to SUMJ (1C, 2C). Adding a suitable resistor to either ground or to the positive supply is a simple way of achieving this. The nominal 2.5 V null is for a symmetrical swing range at RATEOUT (1B, 2A). However, a nonsymmetric output swing may be suitable in some applications. Note that if a resistor is connected to the positive supply, then supply disturbances may reflect some null instabilities. Digital supply noise should be avoided, particularly in this case (see the Supply and Common Considerations section). f OUT = 1/ (2 × π × ROUT × COUT ) and can be well controlled since ROUT has been trimmed during manufacturing to be 180 kΩ ± 1%. Any external resistor applied between the RATEOUT (1B, 2A) and SUMJ (1C, 2C) pins results in The resistor value to use is approximately ROUT = (180 kΩ × REXT )/ (180 kΩ × REXT ) The –3 dB frequency is set by RSEN (the parallel combination of RSEN1 and RSEN2) at about 3.5 kΩ nominal; CMID is less well controlled since RSEN1 and RSEN2 have been used to trim the rate sensitivity during manufacturing and have a ±35% tolerance. Its primary purpose is to limit the high frequency demodulation artifacts from saturating the final amplifier stage. Thus, this pole of nominally 400 Hz @ 0.1 µF need not be precise. Lower frequency is preferable, but its variability usually requires it to be about 10 times greater (in order to preserve phase integrity) than the well-controlled output pole. In general, both –3 dB filter frequencies should be set as low as possible to reduce the amplitude of these high frequency artifacts and to reduce the overall system noise. INCREASING MEASUREMENT RANGE The full-scale measurement range of the ADXRS300 can be increased by placing an external resistor between the RATEOUT (1B, 2A) and SUMJ (1C, 2C) pins, which would parallel the internal ROUT resistor that is factory-trimmed to 180 kΩ. For example, a 330 kΩ external resistor will give ~50% increase in the full-scale range. This is effective for up to a 4× increase in the full-scale range (minimum value of the parallel resistor allowed is 45 kΩ). Beyond this amount of external sensitivity reduction, the internal circuitry headroom requirements prevent further increase in the linear full-scale output range. The drawbacks of modifying the full-scale range are the additional output null drift (as much as 2°/sec over temperature) and the readjustment of the initial null bias (see the Null Adjust section). USING THE ADXRS300 WITH A SUPPLYRATIOMETRIC ADC The ADXRS300’s RATEOUT signal is nonratiometric, i.e., neither the null voltage nor the rate sensitivity is proportional to the supply. Rather they are nominally constant for dc supply changes within the 4.75 V to 5.25 V operating range. If the ADXRS300 is used with a supply-ratiometric ADC, the ADXRS300’s 2.5 V output can be converted and used to make corrections in software for the supply variations. R NULL = (2.5 × 180,000) / (V NULL0 – V NULL1 ) VNULL0 is the unadjusted zero rate output, and VNULL1 is the target null value. If the initial value is below the desired value, the resistor should terminate on common or ground. If it is above the desired value, the resistor should terminate on the 5 V supply. Values are typically in the 1 MΩ to 5 MΩ range. If an external resistor is used across RATEOUT and SUMJ, then the parallel equivalent value is substituted into the preceding equation. Note that the resistor value is an estimate since it assumes VCC = 5.0 V and VSUMJ = 2.5 V. SELF-TEST FUNCTION The ADXRS300 includes a self-test feature that actuates each of the sensing structures and associated electronics in the same manner as if subjected to angular rate. It is activated by standard logic high levels applied to inputs ST1 (5F, 5G), ST2 (4F, 4G), or both. ST1 causes a voltage at RATEOUT equivalent to typically –270 mV, and ST2 causes an opposite +270 mV change. 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. Since ST1 and ST2 are not necessarily closely matched, actuating both simultaneously may result in an apparent null bias shift. CONTINUOUS SELF-TEST The one-chip integration of the ADXRS300 gives it higher reliability than is obtainable with any other high volume manufacturing method. Also, it is manufactured under a mature BIMOS process that has field-proven reliability. As an additional failure detection measure, power-on self-test can be performed. However, some applications may warrant continuous self-test while sensing rate. Application notes outlining continuous selftest techniques are also available on the Analog Devices website. Rev. B | Page 7 of 8 ADXRS300 OUTLINE DIMENSIONS A1 CORNER INDEX AREA 7.00 BSC SQ 7 6 5 4 3 2 1 A BALL A1 INDICATOR B C BOTTOM VIEW TOP VIEW D E F G 4.80 BSC DETAIL A DETAIL A 3.20 2.50 0.44 0.25 3.65 MAX 0.15 MAX COPLANARITY 0.60 SEATING 0.55 PLANE 0.50 BALL DIAMETER 0.80 BSC Figure 6. 32-Lead Chip Scale Ball Grid Array [CSPBGA] (BC-32) Dimensions shown in millimeters ORDERING GUIDE Model ADXRS300ABG ADXRS300ABG-Reel ADXRS300EB Temperature Range –40°C to +85°C –40°C to +85°C Package Description 32-Lead BGA 32-Lead BGA Evaluation Board © 2004 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03227–0–3/04(B) Rev. B | Page 8 of 8 Package Outline BC-32 BC-32