Doc.Nr. 82 1178 00
Murata Electronics Oy Subject to changes 1/16
www.muratamems.fi Doc.Nr. 82 1178 00 Rev.A2
Self test 2
Sensing
element 1
Sensing
element 2
SPI interface
Self test 1
Signal conditioning
and filtering
A/D conversion
Signal conditioning
and filtering
EEPROM
calibration
memory
9 ST_2
10 ST_1
12 VDD
6 GND
11 OUT_1
5 OUT_2
1 SCK
3 MISO
4 MOSI
7 CSB
Temperature
Sensor
SCA100T-D07 2-AXIS HIGH PERFORMANCE ANALOG ACCELEROMETER
Features
Applications
Measurement range ±12g
Measurement bandwidth 400 Hz
Low noise ratiometric analog voltage outputs
Excellent bias stability over temperature and time
Digital SPI temperature output
Comprehensive failure detection features
o True self test by deflecting the sensing
element's proof mass with electrostatic force.
o Continuous sensing element interconnection
failure check.
o Continuous memory parity check.
RoHS and lead free soldering process compliant
Robust design, high shock durability (20000g)
SCA100T-D07 is targeted to inertial sensing
applications with high stability and tough
environmental requirements. Typical application
include
IMU, AHRS
Avionics
UAV
Navigation and guidance instruments
Platform stabilization
Vibration monitoring
Oil & Gas surveying and drilling
Train and Rail industry
General Description
The SCA100T-D07 is a 3D-MEMS-based dual axis accelerometer that enables tactical grade performance for
Inertial Measurement Units (IMUs) operating in tough environmental conditions. The measuring axes of the
sensor are parallel to the mounting plane and orthogonal to each other. Wide measurement range and bandwidth,
low repeatable temperature behavior, low output noise, together with a very robust sensing element and
packaging design, make the SCA100T-D07 the ideal choice for challenging inertial sensing applications.
Product Family Specification
Data Sheet
Figure 1. Functional block diagram
SCA100T Series
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www.muratamems.fi Doc. nr. 82 1178 00 Rev.A2
TABLE OF CONTENTS
1 Electrical Specifications ..................................................................................................... 3
1.1 Absolute Maximum Ratings ................................................................................................... 3
1.2 Performance Characteristics .................................................................................................. 3
1.3 Parameter ................................................................................................................................ 3
1.4 Electrical Characteristics ....................................................................................................... 4
1.5 SPI Interface DC Characteristics ............................................................................................ 4
1.6 SPI Interface AC Characteristics ............................................................................................ 4
1.7 SPI Interface Timing Specifications ....................................................................................... 5
1.8 Electrical Connection.............................................................................................................. 6
1.9 Typical Performance Characteristics .................................................................................... 6
2 Functional Description ....................................................................................................... 9
2.1 Measuring Directions .............................................................................................................. 9
2.2 Ratiometric Output .................................................................................................................. 9
2.3 SPI Serial Interface .................................................................................................................. 9
2.4 Self Test and Failure Detection Modes ................................................................................ 12
2.5 Temperature Measurement .................................................................................................. 13
3 Application Information .................................................................................................... 14
3.1 Recommended Circuit Diagrams and Printed Circuit Board Layouts ............................... 14
3.2 Recommended Printed Circuit Board Footprint ................................................................. 15
4 Mechanical Specifications and Reflow Soldering .......................................................... 15
4.1 Mechanical Specifications (Reference only) ....................................................................... 15
4.2 Reflow Soldering ................................................................................................................... 16
SCA100T Series
Murata Electronics Oy Subject to changes 3/16
www.muratamems.fi Doc. nr. 82 1178 00 Rev.A2
1 Electrical Specifications
The product version specific performance specifications are listed in the table SCA100T
performance characteristics below. Vdd=5.00V and ambient temperature unless otherwise
specified.
1.1 Absolute Maximum Ratings
-0.3 V to +5.5V
-0.3V to (VDD + 0.3V)
-55°C to +125°C
-40°C to +125°C
Drop from 1 meter onto a concrete surface
(20000g). Powered or non-powered
1.2 Performance Characteristics
1.3 Parameter
Condition
Min(1
Typical
Max(1
Units
Measuring range
Nominal
-12
+12
g
Frequency response
–3dB LP
250
400
550
Hz
Offset (Output at 0g)
Ratiometric output
Vdd/2
Vdd/2
V
Offset Digital Output
1024
LSB
Offset Calibration error
-45
45
mg
Offset Temperature
Dependency
-25…+85°C
-200
200
mg
mg
-40…+125°C
-300
300
Offset Temperature
Hysteresis
-40…+125°C
-50
50
mg
Sensitivity
0.17
V/g
Sensitivity Digital Output
70
LSB / g
Sensitivity Calibration error
-2
+2
%
Sensitivity Temperature
Dependency
-25…+85°C
-2
+2
%
-40…+125°C
-2.5
+2.5
%
Linearity error
-15…+85ºC
-60
60
mg
+25ºC
-25
25
mg
Digital Output Resolution
11
11
Bits
Output Noise Density
From DC...100Hz
95
120
Hz/g
Ratiometric error
Vdd = 4.75...5.25V
-2
+2
%
Cross-axis sensitivity
Max.
-3.5
+3.5
%
Note 1. Min/Max values are +/-3 sigma of test population
SCA100T Series
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1.4 Electrical Characteristics
Parameter
Condition
Min.
Typ
Max.
Units
Supply voltage Vdd
4.75
5.0
5.25
V
Current
consumption
Vdd = 5 V; No load
4
5
mA
Operating
temperature
-40
+125
°C
Analog resistive
output load
Vout to Vdd or GND
10
kΩ
Analog capacitive
output load
Vout to Vdd or GND
20
nF
Start-up delay
Reset and parity check
10
ms
1.5 SPI Interface DC Characteristics
Parameter
Conditions
Symbol
Min
Typ.
Max
Unit
Input terminal CSB
Pull up current
VIN = 0 V
IPU
13
22
35
A
Input high voltage
VIH
4
Vdd+0.3
V
Input low voltage
VIL
-0.3
1
V
Hysteresis
VHYST
0.23*Vdd
V
Input capacitance
CIN
2
pF
Input terminal MOSI, SCK
Pull down current
VIN = 5 V
IPD
9
17
29
A
Input high voltage
VIH
4
Vdd+0.3
V
Input low voltage
VIL
-0.3
1
V
Hysteresis
VHYST
0.23*Vdd
V
Input capacitance
CIN
2
pF
Output terminal MISO
Output high voltage
I > -1mA
VOH
Vdd-
0.5
V
Output low voltage
I < 1 mA
VOL
0.5
V
Tri-state leakage
0 < VMISO <
Vdd
ILEAK
5
100
pA
1.6 SPI Interface AC Characteristics
Parameter
Condition
Min.
Typ.
Max.
Units
Output load
@500kHz
1
nF
SPI clock frequency
500
kHz
Internal A/D conversion time
150
s
Data transfer time
@500kHz
38
s
SCA100T Series
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CSB
SCK
MOSI
MISO
TLS1
TCH
THOL
TSET
TVAL1
TVAL2
TLZ
TLS2
TLH
MSB in
MSB out
LSB in
LSB out
DATA out
DATA in
TCL
1.7 SPI Interface Timing Specifications
Parameter
Conditions
Symbol
Min.
Typ.
Max.
Unit
Terminal CSB, SCK
Time from CSB (10%)
To SCK (90%)
TLS1
120
ns
Time from SCK (10%)
To CSB (90%)
TLS2
120
ns
Terminal SCK
SCK low time
Load
capacitance at
MISO < 2 nF
TCL
1
s
SCK high time
Load
capacitance at
MISO < 2 nF
TCH
1
s
Terminal MOSI, SCK
Time from changing MOSI
(10%, 90%) to SCK (90%).
Data setup time
TSET
30
ns
Time from SCK (90%) to
changing MOSI (10%,90%).
Data hold time
THOL
30
ns
Terminal MISO, CSB
Time from CSB (10%) to stable
MISO (10%, 90%).
Load
capacitance at
MISO < 15 pF
TVAL1
10
100
ns
Time from CSB (90%) to high
impedance state of
MISO.
Load
capacitance at
MISO < 15 pF
TLZ
10
100
ns
Terminal MISO, SCK
Time from SCK (10%) to stable
MISO (10%, 90%).
Load
capacitance at
MISO < 15 pF
TVAL2
100
ns
Terminal CSB
Time between SPI cycles, CSB at
high level (90%)
TLH
15
s
When using SPI commands
RDAX, RDAY, and RWTR: Time
between SPI cycles, CSB at high
level (90%)
TLH
150
s
Figure 2. Timing diagram for SPI communication
SCA100T Series
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1.8 Electrical Connection
If the SPI interface is not used SCK (pin1), MISO (pin3), MOSI (pin4) and CSB (pin7) must be left
floating. Self-test can be activated applying logic “1” (positive supply voltage level) to ST_1 or ST_2
pins (pins 10 or 9). Self-test must not be activated for both channels at the same time. If ST feature
is not used pins 9 and 10 must be left floating or connected to GND. Acceleration signals are
provided from pins OUT_1 and OUT_2.
1
2
3
4
5
6 7
8
9
10
11
12SCK
Ext_C_1
MISO
MOSI
OUT_2
VSS CSB
Ext_C_2
ST_2
ST_1/Test_in
OUT_1
VDD
Figure 3. SCA100T electrical connection
No.
Node
I/O
Description
1
SCK
Input
Serial clock
2
NC
Input
No connect, left floating
3
MISO
Output
Master in slave out; data output
4
MOSI
Input
Master out slave in; data input
5
Out_2
Output
Y axis Output (Ch 2)
6
GND
Supply
Ground
7
CSB
Input
Chip select (active low)
8
NC
Input
No connect, left floating
9
ST_2
Input
Self test input for Ch 2
10
ST_1
Input
Self test input for Ch 1
11
Out_1
Output
X axis Output (Ch 1)
12
VDD
Supply
Positive supply voltage (+5V DC)
1.9 Typical Performance Characteristics
Typical offset and sensitivity temperature dependencies of the SCA100T are presented in following
diagrams. These results represent the typical performance of SCA100T components. The mean
value and 3 sigma limit (mean ± 3× standard deviation) and specification limits are presented in
following diagrams. The 3 sigma limits represents 99.73% of the SCA100T population.
SCK
MISO
MOSI
OUT_2
GND
VDD
OUT_1
ST_1
ST_2
CSB
SCA100T Series
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SCA100T-D07 Offset Temperature Dependency
-400
-300
-200
-100
0
100
200
300
-40 -20 0 20 40 60 80 100 120
Temperature [ºC]
Offset error [mg]
-3 sigma
Average
+3 sigma
Figure 4. Typical temperature behavior of SCA100T-D07 offset
SCA100T-D07 Sensitivity Errors Over Temperature
-3.00 %
-2.00 %
-1.00 %
0.00 %
1.00 %
2.00 %
3.00 %
-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature[ºC]
Sensitivity Error[%]
Average
+3 sigma
-3 sigma
Figure 5. Typical temperature behavior of SCA100T-D07 sensitivity
SCA100T Series
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Frequency response
-30
-27
-24
-21
-18
-15
-12
-9
-6
-3
0
10 100 1000 10000
Frequency[Hz]
Attenuation[dB]
Figure 6. Frequency response of SCA100T-D07
Typical SCA100T-D07 Non-Linearity of X-axis in
25ºC
-25
-20
-15
-10
-5
0
5
10
15
20
25
-12 -9 -6 -3 0 3 6 9 12
Acceleration[g]
Error[mg]
Figure 7. Typical non-linearity of SCA100T-D07 fitted to straight line in room temperature
SCA100T Series
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2 Functional Description
2.1 Measuring Directions
X-axis
Y-axis
2.2 Ratiometric Output
Ratiometric output means that the zero offset point and sensitivity of the sensor are proportional to
the supply voltage. If the SCA100T supply voltage is fluctuating the SCA100T output will also vary.
When the same reference voltage for both the SCA100T sensor and the measuring part (A/D-
converter) is used, the error caused by reference voltage variation is automatically compensated
for.
2.3 SPI Serial Interface
A Serial Peripheral Interface (SPI) system consists of one master device and one or more slave
devices. The master is defined as a micro controller providing the SPI clock and the slave as any
integrated circuit receiving the SPI clock from the master. The ASIC in Murata Electronics’ products
always operates as a slave device in master-slave operation mode.
The SPI has a 4-wire synchronous serial interface. Data communication is enabled by a low active
Slave Select or Chip Select wire (CSB). Data is transmitted by a 3-wire interface consisting of wires
for serial data input (MOSI), serial data output (MISO) and serial clock (SCK).
VOUT > VOUT =2.5V > VOUT
Figure 8. The measuring directions of the SCA100T
SCA100T Series
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DATA OUT (MOSI)
DATA IN (MISO)
SERIAL CLOCK (SCK)
SS0
SS1
SS2
SS3
MASTER
MICROCONTROLLER
SI
SO
SCK
CS
SLAVE
SI
SO
SCK
CS
SI
SO
SCK
CS
SI
SO
SCK
CS
Figure 9. Typical SPI connection
The SPI interface in Murata products is designed to support any micro controller that uses SPI bus.
Communication can be carried out by either a software or hardware based SPI. Please note that in
the case of hardware based SPI, the received acceleration data is 11 bits. The data transfer uses
the following 4-wire interface:
MOSI master out slave in µP → SCA100T
MISO master in slave out SCA100T → µP
SCK serial clock µP → SCA100T
CSB chip select (low active) µP → SCA100T
Each transmission starts with a falling edge of CSB and ends with the rising edge. During
transmission, commands and data are controlled by SCK and CSB according to the following rules:
commands and data are shifted; MSB first, LSB last
each output data/status bits are shifted out on the falling edge of SCK (MISO line)
each bit is sampled on the rising edge of SCK (MOSI line)
after the device is selected with the falling edge of CSB, an 8-bit command is received. The
command defines the operations to be performed
the rising edge of CSB ends all data transfer and resets internal counter and command register
if an invalid command is received, no data is shifted into the chip and the MISO remains in high
impedance state until the falling edge of CSB. This reinitializes the serial communication.
data transfer to MOSI continues immediately after receiving the command in all cases where
data is to be written to SCA100T’s internal registers
data transfer out from MISO starts with the falling edge of SCK immediately after the last bit of
the SPI command is sampled in on the rising edge of SCK
maximum SPI clock frequency is 500kHz
maximum data transfer speed for RDAX and RDAY is 5300 samples per sec / channel
SCA100T Series
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SPI command can be either an individual command or a combination of command and data. In the
case of combined command and data, the input data follows uninterruptedly the SPI command and
the output data is shifted out parallel with the input data.
The SPI interface uses an 8-bit instruction (or command) register. The list of commands is given in
Table below.
Command
name
Command
format
Description:
MEAS
00000000
Measure mode (normal operation mode after power on)
RWTR
00001000
Read temperature data register
STX
00001110
Activate Self test for X-channel
STY
00001111
Activate Self test for Y-channel
RDAX
00010000
Read X-channel acceleration
RDAY
00010001
Read Y-channel acceleration
Measure mode (MEAS) is standard operation mode after power-up. During normal operation, the
MEAS command is the exit command from Self test.
Read temperature data register (RWTR) reads temperature data register during normal operation
without affecting the operation. The temperature data register is updated every 150 µs. The load
operation is disabled whenever the CSB signal is low, hence CSB must stay high at least 150 µs
prior to the RWTR command in order to guarantee correct data. The data transfer is presented in
Figure 10 below. The data is transferred MSB first. In normal operation, it does not matter what
data is written into temperature data register during the RWTR command and hence writing all
zeros is recommended.
Figure 1. Command and 8 bit temperature data transmission over the SPI
Self test for X-channel (STX) activates the self test function for the X-channel (Channel 1). The
internal charge pump is activated and a high voltage is applied to the X-channel acceleration
sensor element electrode. This causes the electrostatic force that deflects the beam of the sensing
element and simulates the acceleration to the positive direction. The self-test is de-activated by
giving the MEAS command. The self test function must not be activated for both channels at
the same time.
Self test for Y-channel (STY) activates the self test function for the Y-channel (Channel 2). The
internal charge pump is activated and a high voltage is applied to the Y-channel acceleration
sensor element electrode.
Read X-channel acceleration (RDAX) accesses the AD converted X-channel (Channel 1)
acceleration signal stored in acceleration data register X.
SCA100T Series
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Read Y-channel acceleration (RDAY) accesses the AD converted Y-channel (Channel 2)
acceleration signal stored in acceleration data register Y.
During normal operation, acceleration data registers are reloaded every 150 µs. The load operation
is disabled whenever the CSB signal is low, hence CSB must stay high at least 150 µs prior the
RDAX command in order to guarantee correct data. Data output is an 11-bit digital word that is fed
out MSB first and LSB last.
Figure 10. Command and 11 bit acceleration data transmission over the SPI
2.4 Self Test and Failure Detection Modes
To ensure reliable measurement results the SCA100T has continuous interconnection failure and
calibration memory validity detection. A detected failure forces the output signal close to power
supply ground or VDD level, outside the normal output range. The normal output ranges are:
analog 0.25-4.75 V (@Vdd=5V) and SPI 102...1945 counts.
The calibration memory validity is verified by continuously running parity check for the control
register memory content. In the case where a parity error is detected, the control register is
automatically re-loaded from the EEPROM. If a new parity error is detected after re-loading data
both analog output voltages are forced to go close to ground level (<0.25 V) and SPI outputs go
below 102 counts.
The SCA100T also includes a separate self test mode. The true self test simulates acceleration, or
deceleration, using an electrostatic force. The electrostatic force simulates acceleration that is high
enough to deflect the proof mass to the extreme positive position, and this causes the output signal
to go to the maximum value. The self test function is activated either by a separate on-off
command on the self test input, or through the SPI.
The self-test generates an electrostatic force, deflecting the sensing element’s proof mass, thus
checking the complete signal path. The true self test performs following checks:
Sensing element movement check
ASIC signal path check
PCB signal path check
Micro controller A/D and signal path check
The created deflection can be seen in both the SPI and analogue output. The self test function is
activated digitally by a STX or STY command, and de-activated by a MEAS command. Self test
can be also activated applying logic”1” (positive supply voltage level) to ST pins (pins 9 & 10) of
SCA100T Series
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083.1 197
Counts
T
SCA100T. The self test Input high voltage level is 4 – Vdd+0.3 V and input low voltage level is 0.3
– 1 V. The self test function must not be activated for both channels at the same time.
Figure 11. Self test wave forms
V1 = initial output voltage before the self test function is activated.
V2 = output voltage during the self test function.
V3 = output voltage after the self test function has been de-activated and after stabilization time
Please note that the error band specified for V3 is to guarantee that the output is within 5% of the
initial value after the specified stabilization time. After a longer time (max. 1 second) V1=V3.
T1 = Pulse length for Self test activation
T2 = Saturation delay
T3 = Recovery time
T4 = Stabilization time =T2+T3
T5 = Rise time during self test.
Self test characteristics:
T1 [ms]
T2 [ms]
T3 [ms]
T4 [ms]
T5 [ms]
V2:
V3:
20-100
Typ. 25
Typ. 30
Typ. 55
Typ. 15
Min 0.95*VDD
(4.75V @Vdd=5V)
0.95*V1-1.05*V1
2.5 Temperature Measurement
The SCA100T has an internal temperature sensor, which is used for internal offset compensation.
The temperature information is also available for additional external compensation. The
temperature sensor can be accessed via the SPI interface and the temperature reading is an 8-bit
word (0…255). The transfer function is expressed with the following formula:
Where:
Counts Temperature reading
T Temperature in °C
The temperature measurement output is not calibrated. The internal temperature compensation
routine uses relative results where absolute accuracy is not needed. If the temperature
Vout
5V
0 V
T5
T1
T2
T3
T4
V1
V2
V3
ST pin
voltage
0 V
5 V
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measurement results are used for additional external compensation then one point calibration in
the system level is needed to remove the offset. With external one point calibration the accuracy of
the temperature measurement is about ±1 °C.
3 Application Information
3.1 Recommended Circuit Diagrams and Printed Circuit Board Layouts
The SCA100T should be powered from a well regulated 5 V DC power supply. Coupling of digital
noise to the power supply line should be minimized. 100nF filtering capacitor between VDD pin 12
and GND plane must be used.
The SCA100T has a ratiometric output. To get the best performance use the same reference
voltage for both the SCA100T and Analog/Digital converter.
Use low pass RC filters with 5.11 kΩ and 10nF on the SCA100T outputs to minimize clock noise.
Locate the 100nF power supply filtering capacitor close to VDD pin 12. Use as short a trace length
as possible. Connect the other end of capacitor directly to the ground plane. Connect the GND pin
6 to underlying ground plane. Use as wide ground and power supply planes as possible. Avoid
narrow power supply or GND connection strips on PCB.
Figure 12. Analog connection and layout example
Figure 13. SPI connection example
SCA100T Series
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3.2 Recommended Printed Circuit Board Footprint
Figure 14. Recommended PCB footprint
4 Mechanical Specifications and Reflow Soldering
4.1 Mechanical Specifications (Reference only)
Lead frame material: Copper
Plating: Nickel followed by Gold
Solderability: JEDEC standard: JESD22-B102-C
RoHS compliance: RoHS compliant lead free component.
Co-planarity error: 0.1mm max.
Part weight: <1.2 g
Figure 15. Mechanical dimensions of the SCA100T (Dimensions in mm)
SCA100T Series
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4.2 Reflow Soldering
The SCA100T is suitable for Sn-Pb eutectic and Pb- free soldering process and mounting with
normal SMD pick-and-place equipment.
Figure 16. Recommended SCA100T body temperature profile during reflow soldering. Ref.
IPC/JEDEC J-STD-020B.
Profile feature
Sn-Pb Eutectic
Assembly
Pb-free Assembly
Average ramp-up rate (TL to TP)
3°C/second max.
3°C/second max.
Preheat
- Temperature min (Tsmin)
- Temperature max (Tsmax)
- Time (min to max) (ts)
100°C
150°C
60-120 seconds
150°C
200°C
60-180 seconds
Tsmax to T, Ramp up rate
3°C/second max
Time maintained above:
- Temperature (TL)
- Time (tL)
183°C
60-150 seconds
217°C
60-150 seconds
Peak temperature (TP)
240 +0/-5°C
250 +0/-5°C
Time within 5°C of actual Peak Temperature (TP)
10-30 seconds
20-40 seconds
Ramp-down rate
6°C/second max
6°C/second max
Time 25° to Peak temperature
6 minutes max
8 minutes max
The Moisture Sensitivity Level of the part is 3 according to the IPC/JEDEC J-STD-020B. The part
should be delivered in a dry pack. The manufacturing floor time (out of bag) in the customer’s end
is 168 hours.
Notes:
Preheating time and temperatures according to guidance from solder paste manufacturer.
It is important that the part is parallel to the PCB plane and that there is no angular alignment
error from intended measuring direction during assembly process.
Wave soldering is not recommended.
Ultrasonic cleaning is not allowed. The sensing element may be damaged by an ultrasonic
cleaning process.