CAS200 Dual-Axis Accelerometer Technical Datasheet

CAS200 Dual-Axis Accelerometer Technical Datasheet
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
1 General Description
Actual size
Y
CAS214 - C
X
Features
• Small (10.4 x 6.0 x 2.2mm)
• Excellent bias repeatability over temperature
• Dual-axis MEMS accelerometer in a hermetically
sealed ceramic LCC surface mount package for
temperature and humidity resistance
• Five dynamic range options; ±0.85g, ±2.5g,
±10g, ±30g ±96g
• Analogue and digital (SPI®) outputs for linear
acceleration and temperature
• Wide bandwidth (typically 170Hz digital,
250Hz analogue)
• Temperature range -40 to +125ºC
• Low power consumption (3mA Typ) from a 3.3V supply
• Integral temperature sensor
• RoHS compliant
Applications
•
•
•
•
•
•
•
•
•
Aerospace and industrial
Aircraft AHRS and controls
Platform stabilisation
Drilling guidance
Surveying and mapping
Land and marine navigation
Transportation
Inertial measurement units
Levelling and tilt sensing
Gemini TM is a new family of integrated MEMS
accelerometers from Silicon Sensing, providing
high performance dual-axis linear acceleration
measurement in a small surface mounted package.
It comprises a dual-axis MEMS sensing device with
a dedicated control ASIC in a single ceramic LCC
package. Sensor data is output via analogue and
digital (SPI®) interfaces.
The CAS200 series of parts provides two in-plane
axes of linear acceleration sensing and is available in five
different dynamic ranges:
•
•
•
•
•
±0.85g - CAS211
±2.5g - CAS212
±10g - CAS213
±30g - CAS214
±96g - CAS215
CAS200 is supplied as a PCBA surface mountable
standard LCC ceramic packaged device, which
is hermetically sealed providing full environmental
protection.
Precise linear acceleration sensing is achieved by a
Silicon MEMS detector forming an orthogonal pair
of sprung masses. Each mass provides the moving
plate of a variable capacitance formed by an array
of interlaced ‘fingers’. This structure also provides
critical damping to prevent resonant gain. Linear
acceleration results in a change of capacitance which
is measured by demodulation of the square wave
excitation.
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 1
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
2.7 to 3.6V
Vdd
X
X Drive
C1
10µF
XPO
Demod
XP/O
YPO
Demod
YP/O
Vref
C2
0.1µF
Y
Vss
Y Drive
Acc_Vdd_cap
Vref_cap
Acc X ANA
C3
0.1µF
C4
0.1µF
Acc Y ANA
PROG
Temp_Out
Temp Sen 1
Calibration
Interface Control
BIT
ADC
SS
Dclk
Data_Out
Data_In
Interface
C.G.18577
Figure 1.1 CAS200 Functional Block Diagram
CAS200 Accelerometer Proof Mass CofG
:
2.18
10.40
12
11
10
9
8
7
7
8
9
10
11
12
(C)
X
X
+ ve
6.00
(D)
Y
13
14
CL
14
13
(B)
Y
Y
(A)
1
(A) = 3.10
(B) = 0.95
(C) = 3.15
(D) = 0.90
(E) = 1.00
2
3
4
5
6
6
5
4
3
2
1
(E)
CL
X + ve
All dimensions
in millimetres.
All dimensions
in millimetres.
C.G.18580
Figure 1.2 CAS200 Overall Dimensions
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 2
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
2 Ordering Information
Part
Number
Sense Axes
Description
Measurement
Range
CAS211
±0.85g
CAS212
±2.5g
CAS213
Y
Dual-axis, (X,Y) linear
accelerometer
CAS214 - C
CAS214
X
CAS21102-0302
±0.85g
CAS21202-0302
±2.5g
CAS21502-0302
Supply
Voltage
mm
V
±30g
±96g
CAS21402-0302
Overall
Dimensions
10.4x6.0x2.2H
±10g
CAS215
CAS21302-0302
Mode
Evaluation Boards
for the CAS211, 212,
213, 214 or 215 parts
(includes the sensor).
±10g
Digital SPI®
and
Analogue
2.7~3.6
34x26
±30g
±96g
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 3
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
3 Specification
Unless otherwise specified the following specification
values assume Vdd = 3.15 to 3.45V over the
temperature range -40 to +125°C.
3.1 Digital Output Specification
Parameter
CAS211
CAS212
CAS213
CAS214
CAS215
Notes
±0.85g
±2.5g
±10g
±30g
±96g
–
33,500lsb/g
11,000lsb/g
2,800lsb/g
1,050lsb/g
300lsb/g
Nominal
(non-ratiometric)
±1%
±1%
±1%
±1%
±1%
–
±1.2%
±1.2%
±1.2%
±1.2%
±1.2%
Uncompensated
Scale factor stability
(1 year)
±1,000ppm
±1,000ppm
±1,000ppm
±1,000ppm
±1,000ppm
–
Scale factor non-linearity
0.5% FSR
0.5% FSR
2% FSR
2% FSR
2% FSR
Max error from best fit
straight line over the full
range
Bias setting error
at +25°C
±335lsb
±110lsb
±28lsb
±31lsb
±30lsb
Uncompensated
(see note 1)
Bias run to run variation
at +25°C
±0.35mg
±0.75mg
±0.75mg
±3.0mg
±8.0mg
–
Bias stability (1 year)
±7.5mg
±7.5mg
±7.5mg
±25mg
±75mg
–
Bias variation over
temperature
±50mg
±50mg
±50mg
±150mg
±500mg
Uncompensated
Resolution/threshold
@1Hz
0.03mg
0.10mg
0.10mg
0.30mg
1.0mg
With over-sampling
techniques
50μg/Hz
150μg/Hz
150μg/Hz
350μg/Hz
1,200μg/Hz
Typical
>170Hz
>170Hz
>170Hz
>170Hz
>170Hz
–
0.15mg/g2 @
0.5grms
0.15mg/g2 @
2.0grms
0.15mg/g2 @
8.0grms
0.1mg/g2 @
12grms
0.1mg/g2 @
12grms
Bias change under
applied random
vibration 20Hz to 2kHz
Dynamic range
Scale factor
Scale factor error at
+25°C
Scale factor variation over
temperature
Noise spectral density
Bandwidth
Vibration rectification
Note 1:
The bias setting error is a fixed offset, set with 3.3V
applied to the device. This bias may change for other
applied voltages and can be removed by external
compensation.
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 4
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
3.2 Analogue Output Specification
Parameter
CAS211
CAS212
CAS213
CAS214
CAS215
Notes
±0.85g
±2.5g
±10g
±30g
±96g
–
1,150mV/g
375mV/g
96mV/g
36mV/g
10mV/g
Nominal
(ratiometric)
Scale factor error at
+25°C
±1.5%
±1.5%
±1.5%
±1.5%
±1.5%
–
Scale factor variation over
temperature
±1.2%
±1.2%
±1.2%
±1.2%
±1.2%
Uncompensated
±1,000ppm
±1,000ppm
±1,000ppm
±1,000ppm
±1,000ppm
–
Dynamic range
Scale factor
Scale factor stability
(1 year)
Scale factor asymmetry
±750ppm
±750ppm
±1,500ppm
±2,000ppm
±2,000ppm
Difference between
best fit straight line
slope in positive and
negative ranges
Scale factor non-linearity
0.5% FSR
0.5% FSR
2% FSR
2% FSR
2% FSR
Max error from best fit
straight line over the full
range
Bias run to run variation
at +25°C
±0.35mg
±0.75mg
±0.75mg
±3.0mg
±8.0mg
–
Bias stability (1 year)
±7.5mg
±7.5mg
±7.5mg
±25mg
±75mg
–
Bias variation over
temperature
±50mg
±50mg
±50mg
±150mg
±500mg
Uncompensated
(see note 2)
Resolution/threshold
@1Hz
0.03mg
0.10mg
0.10mg
0.30mg
1.00mg
–
50μg/Hz
150μg/Hz
150μg/Hz
350μg/Hz
1,200μg/Hz
Typical
>250Hz
>250Hz
>250Hz
>250Hz
>250Hz
–
0.15mg/g2 @
0.5grms
0.15mg/g2 @
2.0grms
0.15mg/g2 @
8.0grms
0.1mg/g2 @
12grms
0.1mg/g2 @
12grms
Bias change under
applied random
vibration 20Hz to 2kHz
Noise spectral density
Bandwidth
Vibration rectification
Note 2:
The acceleration outputs are at a nominal Vdd/2 voltage.
Typical variation from device to device is ±10.0mV, and
may change with variation in power supply voltage.
The fixed offset can be removed by external compensation.
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Specification Continued
CAS211, CAS212, CAS213, CAS214 & CAS215
Parameter
Minimum
Typical
Maximum
Notes
Temperature Sensor (Digital Output):
Scale factor
–
11lsb/°C
–
At +25°C
Offset
–
2336lsb
–
At +25°C
Scale factor
–
5mV/°C
–
–
Offset
–
1.49V
–
At +25°C
-5°C
–
+5°C
–
Start up time
–
–
20ms
–
Recovery time
–
–
10ms
From over range/shock
–
0.4grams
–
–
Misalignment
-20mrad
–
20mrad
–
Orthogonality
–
1.7mrad
–
Internal relative to the other
sensor
Temperature Sensor (Analogue Output):
Repeatability
Start Up:
Physical:
Mass
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 6
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
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Technical Datasheet
4 Absolute Minimum/Maximum Ratings
Minimum
Maximum
-0.3V
+4.0V
–
2kV HBM
Temperature (operating)
-40°C
+125°C
Temperature (storage)
-55°C
+150°C
Humidity
–
90% RH non-condensing
Shock (operating)
–
1,000g 1ms 1/2 sine
Shock (non-operational)
–
10,000g 0.5ms 1/2 sine (CAS214, CAS215)
6,500g 0.5ms 1/2 sine (CAS211, CAS212, CSA213)
15 years
–
12,000 hours
–
Electrical:
Vdd
ESD protection
Environmental:
Life:
Unpowered
Powered
Notes:
Exposure to the Absolute Maximum Ratings for
extended periods may affect performance and
reliability.
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 7
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
5 Typical Performance Characteristics
Graphs showing typical performance characteristics for GeminiTM are shown below:
Note: Typical data is with the device powered from a 3.3V supply.
0.25
X
0.4
0.3
0.2
0.1
0
Y
0.20
0.15
0.10
0.05
0.00
Bias (mg)
Bias (mg)
Figure 5.1 CAS211 (0.85g) Bias Distribution
at 20°C
Figure 5.2 CAS212 (2.5g) Bias Distribution
at 20°C
0.60
0.18
X
0.50
0.40
0.30
0.20
0.10
0.00
X
0.16
Y
Bin Fraction (Population)
Bin Fraction (Population)
X
Y
0.5
Bin Fraction (Population)
Bin Fraction (Population)
0.6
Y
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
Bias (mg)
Bias (mg)
Figure 5.3 CAS213 (10g) Bias Distribution
at 20°C
Figure 5.4 CAS214 (30g) Bias Distribution
at 20°C
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 8
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Typical Performance Characteristics Continued
100
0.80
80
Y
60
0.60
Normalised Bias (mg)
Bin Fraction (Population)
0.70
X
0.50
0.40
0.30
0.20
40
20
-60
-40
0
-20
-20
0
60
80
100
120
140
-60
-80
0.00
-100
Temperature (°C)
Bias (mg)
Figure 5.5 CAS215 (96g) Bias Distribution
at 20°C
Figure 5.6 CAS211 (0.85g) Accelerometer Y
Bias variation with Temperature
100
100
80
80
60
60
40
20
-40
-20
0
-20
0
20
40
60
80
100
120
-40
-60
140
Normalised Bias (mg)
Normalised Bias (mg)
40
-40
0.10
-60
20
40
20
-60
-40
-20
0
-20
40
60
80
100
120
140
-60
-80
-100
-100
Figure 5.7 CAS212 (2.5g) Accelerometer Y
Bias variation with Temperature
20
-40
-80
Temperature (°C)
0
Temperature (°C)
Figure 5.8 CAS213 (10g) Accelerometer Y
Bias variation with Temperature
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 9
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Typical Performance Characteristics Continued
200
600
400
120
80
40
-60
-40
-20
0
-40
0
20
40
60
80
100
120
140
-80
-120
Normalised Bias (mg)
Normalised Bias (mg)
160
200
-60
-40
-20
0
0
20
40
60
80
100
120
140
-200
-400
-160
-600
Temperature (°C)
Temperature (°C)
Figure 5.9 CAS214 (30g) Accelerometer Y
Bias variation with Temperature
Figure 5.10 CAS215 (96g) Accelerometer Y
Bias variation with Temperature
100
100
80
80
60
60
40
20
-60
-40
-20
0
-20
0
20
40
60
80
100
120
-40
-60
140
Normalised Bias (mg)
Normalised Bias (mg)
-200
40
20
-60
-40
-20
0
-20
0
20
40
60
80
100
120
140
-40
-60
-80
-80
-100
-100
Temperature (°C)
Temperature (°C)
Figure 5.11 CAS211 (0.85g) Accelerometer X
Bias variation with Temperature
Figure 5.12 CAS212 (2.5g) Accelerometer X
Bias variation with Temperature
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 10
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
100
200
80
160
60
120
40
20
-60
-40
-20
0
-20
0
20
40
60
80
100
120
140
-40
-60
Normalised Bias (mg)
Normalised Bias (mg)
Typical Performance Characteristics Continued
80
40
-60
-40
-20
0
-40
0
120
140
Temperature (°C)
Figure 5.14: CAS214(30g) Accelerometer X
Bias variation with Temperature
600
1.50
400
1.00
200
0
20
40
60
80
100
120
-200
-400
140
Normalised SF Error (%)
Normalised Bias (mg)
100
-200
Figure 5.13 CAS213 (10g) Accelerometer X
Bias variation with Temperature
0
80
-160
Temperature (°C)
-20
60
-80
-100
-40
40
-120
-80
-60
20
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
-1.50
-600
Temperature (°C)
Figure 5.15: CAS215(96g) Accelerometer X
Bias variation with Temperature
Temperature (°C)
Figure 5.16 CAS211 (0.85g) Accelerometer Y
SF Error with Temperature
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 11
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
1.50
1.50
1.00
1.00
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
Normalised SF Error (%)
Normalised SF Error (%)
Typical Performance Characteristics Continued
0.50
-60
-40
0
20
40
60
80
100
120
-1.00
Temperature (°C)
Temperature (°C)
Figure 5.17 CAS212 (2.5g) Accelerometer Y
SF Error with Temperature
Figure 5.18 CAS213 (10g) Accelerometer Y
SF Error with Temperature
1.50
1.50
1.00
1.00
0.50
-40
-20
0.00
140
-1.50
0
20
40
60
80
100
120
-0.50
-1.00
140
Normalised SF Error (%)
Normalised SF Error (%)
0.00
-0.50
-1.50
-60
-20
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
-1.50
-1.50
Temperature (°C)
Temperature (°C)
Figure 5.19 CAS214 (30g) Accelerometer Y
SF Error with Temperature
Figure 5.20 CAS215 (96g) Accelerometer Y
SF Error with Temperature
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 12
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
1.50
1.50
1.00
1.00
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
Normalised SF Error (%)
Normalised SF Error (%)
Typical Performance Characteristics Continued
0.50
-60
-40
0
20
40
60
80
100
120
-1.00
Temperature (°C)
Temperature (°C)
Figure 5.21 CAS211 (0.85g) Accelerometer X
SF Error with Temperature
Figure 5.22 CAS212 (2.5g) Accelerometer X
SF Error with Temperature
1.50
1.50
1.00
1.00
0.50
-40
-20
0.00
140
-1.50
0
20
40
60
80
100
120
-0.50
-1.00
-1.50
140
Normalised SF Error (%)
Normalised SF Error (%)
0.00
-0.50
-1.50
-60
-20
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
-1.50
Temperature (°C)
Temperature (°C)
Figure 5.23 CAS213 (10g) Accelerometer X
SF Error with Temperature
Figure 5.24 CAS214 (30g) Accelerometer X
SF Error with Temperature
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 13
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Typical Performance Characteristics Continued
Normalised SF Error (%)
1.50
1.00
0.50
-60
-40
-20
0.00
0
20
40
60
80
100
120
140
-0.50
-1.00
-1.50
Temperature (°C)
Figure 5.25 CAS215 (96g) Accelerometer X
SF Error with Temperature
6 Glossary of Terms
ASIC
Application Specific Integrated Circuit
POR
Power On Reset
BIT
Built-In Test
PPO
Primary Pick-Off
BW
Bandwidth
SF
Scale Factor
CBIT
Commanded Built-In Test
SMT
Surface Mount Technology
CofG
Centre of Gravity
SOG
Silicon On Glass
DAC
Digital to Analogue Converter
T.B.A.
To Be Advised
DRIE
Deep Reactive Ion Etch
T.B.C.
To Be Confirmed
DSBSC
Double Side-Band Suppressed Carrier
Signal
ESD
Electro-Static Damage
HBM
Human Body Model
IPC
Institute of Printed Circuits
LCC
Leadless Chip Carrier
MEMS
Micro-Electro Mechanical Systems
NEC
Not Electrically Connected
(Do Not Connect)
PCBA
Printed Circuit Board Assembly
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 14
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
7 Interface
Physical and electrical inter-connect information.
C3
100nF
13
Pad
NEC
15
Pad
14
Pad
NEC
Vdd
PROG
Acc Y ANA
SS
Data_In
Data_Out
12
CAS200 Series
NEC
6
5
4
C1
10µF
NEC
13
ACC_Vdd_Cap
7
2
11
10
Temp_Out
8
C2
100nF
Acc X ANA
Data_Out
9
9
Vss
Dclk
10
14
NEC
Vref_Cap
SS
11
Data_In
Vdd
Acc Y ANA
15
12
8
7
Dclk
7.1 Physical and Electrical Interface,
Pad Layout and Pinouts
NEC
NEC
Vdd (2.7 to 3.6V)
3
1
C4
100nF
NEC
C.G.18581
11 10
9
8
7
14
C3
100nF
6
5
4
3
C1
10µF
PROG
Vdd
12
NEC
Time_Out
12
Acc X ANA
13
2
1.2 x 5.0
0.9
Vss
0.6 x 2.4
11
10
CAS200 Series
NEC
Vref_Cap
2.55 x 6.1
NEC
C2
100nF
13
ACC_Vdd_Cap
14
Data_Out
15
9
Vdd (2.7V to 3.6V)
Acc Y ANA
8
7
SS
MISO
Figure 7.1 Pinout (Top View)
Slave Select
HOST SYSTEM
MOSI
Vref_Cap
Figure 7.3 Analogue Output Setup
NOTE: Pins 13, 14, & 15 are
for mechanical fixing purposes
and should be soldered to an
unconnected pad (NEC).
Data_In
6
SPI Clock Out
5
Dclk
4
Vss
PROG
3
Temp_Out
2
Acc X ANA
1
ACC_Vdd_Cap
C.G. 18578
1
C4
100nF
2.15
15
2.15
C G 18639
Figure 7.4 Digital Output Setup
3.65
1
4.2
2
3
4
5
6
4.2
6.55
Note:
C.G. 18541
All dimensions in millimetres.
Figure 7.2 Recommended Pad Layout
Note: The Gemini accelerometers are capacitive sensors.
The routing of signal tracks beneath the package
(including power supply signals connecting to
starpoints) can cause an offset in accelerometer
bias. If such routing is unavoidable, the resulting
offset can be removed by compensation at the
higher system level.
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 15
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Pin Name
Signal
Direction
Pin Function
1
Vdd_Cap
–
Used to smooth supply to CAS200.
A 100nF X7R dielectric ceramic capacitor is recommended.
2
PROG
Input
For factory use, must be connected to Vdd in operation
3
Temp_Out
Output
Analogue temperature output. Scaling 5mV/°C at 3.3V supply
- Ambient temperature reading of 1.474V
4
Acc X ANA
Output
X Accelerometer analogue output
5
Vss
–
Return connection for applied power (0V)
6
Vref_Cap
–
Used to decouple the internal voltage reference via an external capacitor. A
100nF X7R dielectric ceramic capacitor is recommended.
7
Data_Out
Output
Digital mode: SPI_MISO. Only enabled when SPI_Select is low. Tri-stated
when SPI_SELECT is high.
8
Dclk
Input
Digital mode: SPI_CLK Internal Pull-up
9
Data_In
Input
Digital mode: SPI_MOSI Internal Pull-up
10
SS
Input
Digital mode: SPI_SELECT Internal Pull-up
11
Acc Y ANA
Input
Y Accelerometer analogue output
12
Vdd
–
Positive power supply to the sensor. Range from 2.7 to 3.6V. Should be
decoupled with a 100nF X7R dielectric ceramic capacitor,
a bulk storage capacitor of 10μF should be nearby.
NEC
–
Not Electrically Connected. These pins provide additional
mechanical fixing to the Host System and should be
soldered to an unconnected pad.
Pin Number
Centre and
Side Pads
(13,14 & 15)
Table 7.1 Input/Output Pin Definitions
Parameter
Minimum
Maximum
Units
Supply
Supply voltage (functional)
2.7
3.6
V
Supply voltage (full specification)
3.15
3.45
V
Supply voltage limits
-0.3
4.0
V
–
5
mA
Supply current
Discretes
Input voltage low
-0.5
0.3xVdd
V
Input voltage high
0.7xVdd
Vdd+0.5
V
Output voltage low
–
0.4
V
Output voltage high
0.8xVdd
–
V
–
<1k

Analogue
Output impedance
Output load capacitance
Input impedance
Output source/sink current
–
300
pF
50k
–

–
1
mA
Table 7.2 Electrical Characteristics
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 16
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
7.2 Digital Interface
25μs
This section defines the SPI® interface timing and
the message types and formats to and from the
GeminiTM CAS200 sensor.
The SPI® interface, when selected, will be a 4-wire
interface with the following signals:
Dclk
Data_In
Data_Out
SS
SPI® clock
Message data input to sensor
Message data output by sensor
Select sensor
Units
Input voltage low
-0.5
0.3xVdd
V
Input voltage high
0.7xVdd
Vdd+0.5
V
Output voltage low
–
0.4
V
Output voltage high
0.8xVdd
–
V
μA
μA
-2
2
10
50
SPI® Clock_Out
MOSI & MISO
This section defines the types and formats of the
messages to the GeminiTM sensor.
Maximum
Pull-up current
Slave Select
7.4 SPI® Message Format
Minimum
Leakage current
15μs
Figure 7.5 SPI ® Timing Diagram
Signal electrical characteristics are defined in
Table 7.3.
Parameter
5μs
Table 7.3 SPI® Electrical Characteristics
SPI_SELECT, SPI_CLK and SPI_MOSI all have internal
pull-up resistors in the sensor ASIC.
SPI_MISO is held in tri_state if SPI_SELECT is High
and is driven if SPI_SELECT is Low.
7.3 Signal Timing
The interface will transfer 6 bytes (48 bits) in each
message. The message rate will be 1kHz
(recommended), (1Hz-min, 10kHz-max) with a
SPI® clock frequency of 1MHz (nom), (100kHz-min
8MHz-max). A sampling rate greater than 500Hz is
recommended to reduce the effects of aliasing.
The sensor will be a slave on the interface. All accesses
shall use SPI® Mode 0.
Figure 7.5 specifies the interface timing for correct
operation.
7.4.1 Messages to ASIC (MOSI)
The messages to the sensor shall be sent in the
following order:
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Command Byte (transmitted first, MSB first)
Data 1
Data 2
Data 3
Data 4
Checksum (see note 3)
Data Format:
Command Byte Bit 7
Set to 0
Bit 6
‘0’ = CBIT disabled
‘1’ = CBIT enabled
Bit 5
Set to 0
Bit 4
Set to 0
Bits 3:0 Message Type
‘0001’ = Acceleration Y and X
Request
‘0010’ = Status and Temperature
Request
‘0000’ = SSSL Use Only
‘0011’ = SSSL Use Only
‘0100’ = SSSL Use Only
‘0101’ = SSSL Use Only
‘0110’ = SSSL Use Only
‘0111’ = SSSL Use Only
Do not
‘1000’ = SSSL Use Only
use
‘1001’ = SSSL Use Only
‘1010’ = SSSL Use Only
‘1011’ = SSSL Use Only
‘1100’ = SSSL Use Only
‘1101’ = SSSL Use Only
‘1110’ = SSSL Use Only
‘1111’ = SSSL Use Only
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 17
Dual-Axis Accelerometer
CAS200
Message Data:
The following table defines the content of each byte
of the input message.
Message Type
Acc Y/Acc X
or
Status/Temp
www.siliconsensing.com
Technical Datasheet
Data Byte
Byte Content
1
Bits (7.0) set to 0x00
2
Bits (7.0) set to 0x00
3
Bits (7.0) set to 0x00
4
Bits (7.0) set to 0x00
Table 7.4 Message Content to GeminiTM
1. To request Acc Y and Acc X data only.
=
=
=
=
=
=
0x01
0x00
0x00
0x00
0x00
0xFE
2. To request Status and Temperature.
Command Byte
Data 1 Byte
Data 2 Byte
Data 3 Byte
Data 4 Byte
Checksum
The messages from the sensor shall be sent in the
following order.
Byte 1:
Byte 2:
Byte 3:
Byte 4:
Byte 5:
Byte 6:
Status Byte (MSB transmitted first)
Data 1
Data 2
Data 3
Data 4
Checksum (see notes 3 and 4)
The data is output in 2’s complement format, most
significant byte first.
Example message data:
Command Byte
Data 1 Byte
Data 2 Byte
Data 3 Byte
Data 4 Byte
Checksum
7.4.2 Message from GeminiTM (MISO)
=
=
=
=
=
=
0x02
0x00
0x00
0x00
0x00
0xFD
Data Format:
The Status Byte content depends on the message
requested.
Status Byte
Bit 7
Sensor BIT Status
‘1’ = BIT Failed
‘0’ = Sensor OK
Bit 6
ACC 1 BIT Status
‘1’ = Acc Y Failed
‘0’ = Acc Y OK
Bit 5
ACC 2 BIT Status
‘1’ = Acc X Failed
‘0’ = Acc X OK
Bit 4
‘1’ = Previous Input Checksum
BIT Failed
‘0’ = Previous Input Checksum
BIT OK
Bit 3
‘0’ = CBIT disabled
‘1’ = CBIT enabled
3. To request CBIT and Acc Y and Acc X data.
Command Byte
Data 1 Byte
Data 2 Byte
Data 3 Byte
Data 4 Byte
Checksum
=
=
=
=
=
=
0x41
0x00
0x00
0x00
0x00
0xBE
4. To request CBIT and Status and Temperature.
Command Byte
Data 1 Byte
Data 2 Byte
Data 3 Byte
Data 4 Byte
Checksum
=
=
=
=
=
=
0x42
0x00
0x00
0x00
0x00
0xBD
Bit 2:0 Output Message Type
‘001’ = Acc Y/ Acc X
‘010’ = Status Message/
Temperature Message
‘000’
‘011’
‘100’
Not used
‘101’
‘110’
‘111’
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 18
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Message Data Content:
5. For the status byte the following conditions apply.
The output message data content will depend on the
command byte from the previous input message.
The content is indicated by bits (2:0) of the Status byte.
Acc_bit _Status (0) = Acc Y
Acc_bit _Status (1) = Acc X
Vref_cap_bit
Acc_cap_bit
CBit_en
Message Type
Acc Y/Acc X
Data Byte
Byte Content
1
Bits (7.0) - Acc Y MS bits (15:8)
2
Bits (7.0) - Acc Y LS bits (7:0)
3
Bits (7.0) - Acc X MS bits (15:8)
4
Bits (7.0) - Acc X LS bits (7:0)
Status Byte 1 (see note 5)
1
Status/Temp
Bit (7:6) - acc_bit_status
Bit 5
- vref_cap_bit
Bit 4
- acc_cap_bit
Bit 3
- cbit_en
Bit 2
‘0’ = OTP Parity OK
‘1’ = OTP Parity Fail
Bit 1
‘0’ = Previous input
checksum Message
Checksum OK
‘1’ = Previous input
checksum Message
Checksum Fail
Bit 0
‘1’
2
Bits (7.0) - (set to ‘0x00’)
3
Bits (7.0) - Temperature MS bits (15:8)
4
Bits (7.0) - Temperature LS bits (7:0)
Table 7.5 Message Content from ASIC
Notes:
3. The checksum is the LS byte of the 1’s complement
of the first 5 bytes of message. If the checksum is
incorrect the input message will be ignored and the
checksum error flagged in the status byte of the next
SPI® message. The content of the message following
a bad checksum message shall be the message type
selected in the last ‘good’ message. The message type
shall default on power-up to Acc Y/Acc X message.
4. The checksum for the output message is calculated
before the message is loaded into the SPI® registers.
When the checksum is about to be calculated, the Data
Bytes are stored and updates to them are inhibited.
The Checksum is then calculated on the Status Byte
and these 4 Data Bytes. The Status Byte can continue
to be updated for a short time after the Checksum has
been calculated. Therefore when the Status Byte, 4
Data Bytes and the Checksum are loaded into the SPI®
register there is a small chance that the Checksum will
be incorrect. It is therefore advised that if a Checksum
Error is detected that the Status Byte should still be
interrogated for the Status, such as BIT Fault.
‘0’ = Pass, ‘1’ = Fail
‘0’ = Pass, ‘1’ = Fail
‘0’ = Pass, ‘1’ = Fail
‘0’ = Pass, ‘1’ = Fail
‘0’ = CBIT OFF,
‘1’ = CBIT ON
7.5 CBIT
The GeminiTM sensor has a Commanded Built in
Test (CBIT) function which stimulates the output
to give a synthetic acceleration output. This allows
the acceleration channel to be functionally tested,
identifying potential failure.
CBIT can be requested using the Command Byte as
detailed in Section 7.4.1. The sensor will respond by
applying a fixed offset to both acceleration outputs.
The offset applied depends on the CAS variant being
used, see Table 7.6 for details. The offset added will
have a ±20% tolerance due to MEMS tolerance effects.
The time taken to apply these offsets will be less than
35ms.
The intrusive nature of CBIT is such that whilst the
sensor may continue to be used to indicate acceleration,
the performance is not guaranteed while CBIT is
asserted.
For full performance acceleration measurement, it is
recommended that 35ms is allowed to elapse following
the de-assertion of CBIT to allow the sensor to settle
again.
Parameter
CAS200 Variant
CAS215 (96g)
Acceleration
(both axes)
Offset Added
32.2g
CAS214 (30.0g)
10g
CAS213 (10.0g)
3.85g
CAS212 (2.50g)
0.96g
CAS211 (0.85g)
0.24g
Table 7.6 CBIT Offset for CAS200 Sensor
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 19
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
8 Design Tools and Resources Available
The following is planned to be available from the website
in the near future.
Item
Description of Resource
Part Number
Order/Download
GeminiTM Brochure: A one page sales brochure describing
the key features of the GeminiTM Accelerometers.
CAS200-00-0100-131
Download
(www.siliconsensing.com)
GeminiTM CAS200 Datasheet: Full technical information
on all part number options. Specification and other essential
information for assembling and interfacing to
GeminiTM Accelerometers, and getting the most out of them.
CAS200-00-0100-132
Download
(www.siliconsensing.com)
GeminiTM Presentation: A useful presentation describing the
features, construction, principles of operation and applications
for the GeminiTM Accelerometers.
—
Download
(www.siliconsensing.com)
Gemini evaluation board: Single Gemini fitted to a small
PCBA for easy customer evaluation and test purposes.
Refer to page 3 for ordering information.
CAS211-02-0302
CAS212-02-0302
CAS213-02-0302
CAS214-02-0302
CAS215-02-0302
Order
Solid Model CAD files for GeminiTM Accelerometers:
Available in .STP and .IGS file format
CAS200-00-0100-408
Download
(www.siliconsensing.com)
Library Parts:
Useful library component files of GeminiTM Accelerometers:
DxDesigner Schematic Symbols.
PADS Decal (Footprint)
PADS Part Type File.
—
Reference Circuit: A useful reference circuit design gerber
files for the GeminiTM Accelerometer for use in host systems.
—
Download
(www.siliconsensing.com)
Questions and Answers: Some useful questions asked
by customers and how we’ve answered them. This is an
informal (uncontrolled) document intended purely as additional
information.
—
Download
(www.siliconsensing.com)
RoHS compliance statement for GeminiTM : GeminiTM is
fully compliant with RoHS.
—
Download
(www.siliconsensing.com)
TM
TM
Download
(www.siliconsensing.com)
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 20
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
9 Cleaning
Item
Due to the natural resonant frequency and
amplification factor (‘Q’) of the sensor, ultrasonic
cleaning should NOT be used to clean the GeminiTM
Accelerometer.
Range
C
1-Z
Year number
YY
00 - 99
Month number
MM
01 - 12
Lot number
LLL
000 - 999
Serial number
XXX
001 - 999
Table 11.1 Part Marking (Serial Number)
10 Soldering Information
Temp (°C)
Code
Configuration
12 Packaging Information
Max 40sec
GeminiTM sensors are supplied in tape format as either
straight strips, or on either full-size or mini-reels,
depending on the quantity being shipped. Table 12.1
defines the packaging method:
260°C
255°C
Max 180sec
217°C
200°C
150°C
Max 120sec
Time (sec)
C.G. 18384
Figure 10.1 Recommended Reflow
Solder Profile
Shipping Quantity
GeminiTM
Qty < 100
Strip of tape
100  Qty  1,000
Tape and mini-reel
(approx. Ø175mm)
Qty > 100
Tape and full-size reel
(approx. Ø330mm)
Table 12.1 Packaging Tape and Reel Format
According to Shipping Quantity
11 Part Markings
The following information in this section defines the
packaging for shipments using full-size reels.
Silicon Sensing
Company Logo
Layer
Type
Quantity
CAS200
Tape and Reel
Max. 1500 pcs/
1 Reel
Inner Bag
Aluminium
Damp-proof Bag
1 Reel/Bag
Inner Box
Cardboard Box
Inner Bag x 1/Inner
Box
Outer Box
Cardboard Box
Inner Box/Outer
Box
Part Number
Serial Number
(See Table 11.1)
Indicates Location
of Pin 1
CAS214
2D Data Matrix Code
Containing the
Production Number
-C
YYMMLL
LXXX
M
ade In Ja
Country of Origin of Final
Assembly and Test
pan
Hardware Configuration
(See Table 11.1)
Figure 11.1 Part Marking
C.G. 18582
Table 12.2 Packaging Information
(Full-Size Reel)
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 21
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Item
Dimension
Quantity
Material
Reel
DR2 23316C
1 Reel
PS
Emboss Tape Carrier Information
12±0.1
ALS-ATA
13.5mm x
480m
1 Roll
PET, PE, PS
Label for
Reel
40mm x
80mm
1 label/Reel
Paper
Desiccant
FA 10g
1 Inner Bag
–
Inner Bag
0.101mm
x 450mm x
530mm
1 Reel/Inner
Bag
MB4800
Tray
451mm x
429mm x
55mm
2 Tray/Outer
Box
–
Pad
451mm x
429mm x
20mm
3 Pad/Outer
Box
Inner Box
413mm x
391mm x
52mm
2 Inner Box/
Outer Box
Cardboard
Outer Box
462mm x
440mm x
208mm
1 Box
Cardboard
Label for
Outer Box
102mm x
127mm
1 label/Outer
Box
Paper
A
A
1.75±0.1
7.3±0.2
Cover Tape
0.3±0.05
10.7±0.1
PS
(Tolerance between
each hole is ±0.2)
11.5±0.1
1 Roll
2±0.1
B
(Tolerance between
each hole is ±0.2)
16±0.3
TE1612091009-2
le
Ho
Emboss
Tape
4±0.1
.1
±0
1.5
1.5+0.1
0
B B VIEW
3.1±0.2
2.6±0.1
B
6.25±0.1
A A VIEW
C.G.18546
Tape Information
Drawing direction
–
PPYYMMLLLLRDD
Made In Japan YYMMLLLL_XXXX
400mm
Empty
CAS214
PPYYMMLLLLRDD
Made In Japan YYMMLLLL_XXXX
CAS214
PPYYMMLLLLRDD
Made In Japan YYMMLLLL_XXXX
PPYYMMLLLLRDD
Made In Japan YYMMLLLL_XXXX
CAS214
CAS214
Sensor packing
400mm ~ 700mm
Empty
2000mm
Cover tape
Pin 1 mark
Table 12.3 Packaging Specification
(Full-Size Reel)
Reel label position
C.G. 18583
Reel Information
110
Label for Reel Information
3 B
3 B
Frame for label
55
9±0.5
Part Number
3±
0.5
W1±1.0
89
0.5
3±
10
270
80±1
CAS214
5±
0.5
330±2
30
22
0.2
0.4
0.6
0.8
B
152
30
Number
W2±1.0
0.5
5±
172
7±0.5
EIAJ.RRM.24.D
Centre details
No. S3011002001
Reel width
2±0.5
21±
0.8
13±0.2
R1
Reel width
mm
8
12
W1
9.5
13.5
W2
13.5
17.5
16
17.5
21.5
24
32
44
25.5
33.5
45.5
29.5
37.5
49.5
C.G. 18579
C.G. 18547
Centre Shape
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 22
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
Inner Bag Packing Information
Outer Box Packing Information
Desiccant
Inner Bag
Pad
Inner Box
Reel
Tray
C.G. 18392
Pad
Inner Box Packing Information
Inner Box
Tray
Pad
Box
Craft Tape
Inner Bag
Inner Box
2
C.G. 18389
1
Maximum of two Reels per Outer Box.
If 1 Reel is contained in Outer Box, label is
pasted in position 1.
If 2 Reels are contained in Outer Box, labels
are pasted in positions 1 and 2.
Each label shows packaged reel information.
C.G. 18390
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 23
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
13 Internal Construction and Theory
of Operation
Construction
Gemini™ is supplied as a PCBA surface mountable
LCC ceramic packaged device. It comprises four
main components; Silicon On Glass (SOG) DualAxis MEMS Accelerometer, ASIC and, the Package
Base and Lid. The MEMS Sensors and ASIC are
housed in a hermetically sealed package cavity with
a nitrogen back-filled partial vacuum, this has particular
advantages over sensors supplied in plastic packages
which have Moisture Sensitivity Level limitations.
CA
YYM S214-C
M
Mad LLLXX
e In
Japa X
n
Multiple inter-digitated fingers create increased
capacitance thus enabling a high signal-to-noise
ratio. The fingers are tapered to increase the resonant
frequency and also have a high aspect ratio to provide
highly stable performance. The differential gaps
between the static electrode fingers and those of the
proof mass provide an air squeeze film with nearcritical damping.
Control of the accelerometer is handled by the GeminiTM
ASIC.
Support flexure
Through-glass via
Lid
Glass Substrates
Seismic proof mass
Cavity
Silicon
Vacuum Cavity
Seal Ring
C.G. 18538
Bond Wires
ASIC
Figure 13.2 Schematic Section of the Silicon
On Glass Accelerometer MEMS Wafer
Sub-Assembly
Dual-Axis Accelerometer MEMS
ASIC
Package Base
Figure 13.1 CAS200 Main Components
Silicon MEMS Dual-Axis Accelerometer
The Gemini TM dual-axis open loop accelerometer
is a one-piece resonating silicon MEMS structure
anodically bonded to top and bottom glass substrates
to form a hermetically sealed Silicon on Glass (SOG)
wafer sub-assembly. A DRIE bulk silicon process
is used to create two orthogonal finger-like spring/
seismic proof mass structures, each measuring
1.8mm square, and with a resonant frequency of
1.8kHz to 5.2kHz. Figure 13.2 shows a schematic
cross section through the SOG wafer.
Capacitive drive and pick-off signals are transmitted
by wire bond interconnections, in through-glass vias,
between the metallised transducer plates on the
MEMS proof mass and the GeminiTM ASIC.
The ASIC is a 3.93mm x 3.2mm device fabricated
using 0.35μm CMOS process. ASIC and MEMS are
physically separate and are connected electrically
by using gold bond wires and thus the ASIC has no
MEMS-to-ASIC internal tracking, meaning there is
reduced noise pick-up. Gold bond wires also connect
the ASIC to the internal bond pads on the Package
Base.
Package Base and Lid
The LCC ceramic Package Base is a multi-layer
aluminium oxide construction with internal bond
wire pads connected through the Package Base via
integral multi-level tungsten interconnects to a series
of external solder pads. Similar integral interconnects
in the ceramic layers connect the Lid to Vss, thus
the sensitive elements are inside a Faraday shield.
Internal and external pads are electroplated gold on
electroplated nickel.
The Package Base incorporates a seal ring on the
upper layer onto which a Kovar ® metal Lid is seam
welded using a rolling resistance electrode, thus
creating a totally hermetic seal. Unlike other MEMS
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 24
CAS200-00-0100-132 Rev 5
Dual-Axis Accelerometer
CAS200
www.siliconsensing.com
Technical Datasheet
packages available on the market, GeminiTM has
a specially developed seam weld process which
eliminates the potential for internal weld spatter.
Inferior designs can cause dislodged weld spatter
which affects reliability due to interference with the
moving MEMS element.
Sensing axis
Theory of Operation (Accelerometer)
Fixed Electrode 1
Fixed support
Fixed Electrode 2
The accelerometer contains a seismic ‘proof mass’
with multiple fingers suspended via a ‘spring’, all of
which is formed in the silicon MEMS structure.
The proof mass is anodically bonded to the top and
bottom glass substrates and thereby fi xed to the
Gemini TM Package Base.
When the Gemini sensor is subjected to a linear
acceleration along its sensitive axis the proof
mass tends to resist motion due to its own inertia,
therefore the mass and it’s fingers becomes
displaced with respect to the interdigitated fi xed
electrode fingers. Gas between the fingers provides
a damping effect. This displacement induces a
differential capacitance between the moving and
fi xed silicon fingers which is proportional to the
applied acceleration.
Proof mass
(includes fingers)
TM
Capacitor plate groups are electrically connected in
pairs at the top and bottom of the proof mass.
In-phase and anti-phase waveforms are applied by
the Gemini TM ASIC separately to the ‘left’ and ‘right’
finger groups. The demodulated waveforms provide
a signal output proportional to linear acceleration.
Figures 13.3(a) and 13.4(b) provide schematics
of the accelerometer structure and control loop
respectively.
C.G. 18613
Figure 13.3(a) Schematic of Accelerometer
Structure
22kHz reference
Signal proportional
to movement of
proof mass
Electrode 2
Out of Phase Square Wave
at 88kHz on Electrode 2
Sensing axis
Amplifier
Demodulator
Low pass
filter
Electrode 1
In Phase Square Wave
at 88kHz on Electrode 1
Output signal
C.G. 18540
Figure 13.4(b) Schematic of Accelerometer
Control Loop
14 Patent Applications
The following patent applications have been filed for
the GeminiTM Accelerometers:
Patent Application
Status
US7047808
Granted
US7267006
Granted
EP1718980
Granted
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
CAS200-00-0100-132 Rev 5
Page 25
Dual-Axis Accelerometer
CAS200
Technical Datasheet
www.siliconsensing.com
Notes
Silicon Sensing Systems Limited
Clittaford Road Southway
Plymouth Devon
PL6 6DE United Kingdom
Silicon Sensing Systems Japan Limited
1-10 Fuso-Cho
Amagasaki
Hyogo 6600891 Japan
T: +44 (0)1752 723330
F: +44 (0)1752 723331
W: siliconsensing.com
T: +81 (0)6 6489 5868
F: +81 (0)6 6489 5919
W: siliconsensing.com
Specification subject to change without notice.
© Copyright 2013
Silicon Sensing Systems Limited
All rights reserved.
Printed in England 09/2013
Date 23/09/2013
CAS200-00-0100-132 Rev 5
DCR No. 710005472
© Copyright 2013 Silicon Sensing Systems Limited. All rights reserved. Silicon Sensing is an Atlantic Inertial Systems, Sumitomo Precision Products joint venture company.
Specification subject to change without notice.
Page 26
CAS200-00-0100-132 Rev 5
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