SCA620-EF8H1A
Murata Electronics Oy 1/11
www.muratamems.fi Doc.nr. 82 1643 00 Rev.B
Product Specification
SCA620-EF8H1A SINGLE AXIS ACCELEROMETER WITH ANALOG
INTERFACE
The SCA620 accelerometer consists of a silicon bulk micro machined sensing element chip and a signal
conditioning ASIC. The chips are mounted on a pre-molded package and wire bonded to appropriate contacts.
The sensing element and ASIC are protected with silicone gel and lid. The sensor has 8 SMD legs (Gull-wing
type).
Features
• Single +5 V supply
• Current consumption 2.5 mA typical
• Ratiometric output in relation to supply
voltage (Vdd = 4.75 V...5.25 V)
• Enhanced failure detection features
o Digitally activated, true self-test by
proof mass deflection using
electrostatic force
o Memory parity check during power
up, and self-test cycle.
o Built in connection failure detection
• Digitally activated, true self-test by proof
mass deflection using electrostatic force
• Wide load drive capability (max. 20 nF)
• True DC response
• Qualified according to AEC-Q100 standard
Applications
SCA620 product family is targeted to automotive
applications with high stability and reliability
requirements. Typical applications include:
• Electronic Stability Control (ESC)
• Engine Vibration Measurement
• Roll Over
• Suspension
• Inclination
Figure 1. Functional block diagram.
ASIC
EEPROM for calibration
constants (32 bit, pari ty check
)
Measurem
en
t
circuitry
Gain &
filtering
4 programming lines
for factory use only
GND
Vout
Sensing
element
Digital self
test input
5V supply
SCA620-EF8H1A
Murata Electronics Oy 2/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
Table of Contents
SCA620-EF8H1A single axis accelerometer with analog interface .................................... 1
F
EATURES
.................................................................................................................................... 1
A
PPLICATIONS
.............................................................................................................................. 1
T
ABLE OF
C
ONTENTS
.................................................................................................................... 2
1.
Electrical Specifications ............................................................................................ 3
1.1.
A
BSOLUTE
M
AXIMUM
R
ATINGS
............................................................................................ 3
1.2.
P
ERFORMANCE
C
HARACTERISTICS
..................................................................................... 3
1.3.
O
FFSET AND SENSITIVITY CALIBRATION
................................................................................ 4
1.4.
E
RROR CALCULATIONS
....................................................................................................... 4
1.5.
S
UPPLY VOLTAGE
............................................................................................................... 5
1.6.
E
LECTRICAL
C
ONNECTION
.................................................................................................. 6
2.
Functional description ............................................................................................... 7
2.1.
M
EASURING DIRECTIONS
.................................................................................................... 7
2.2.
V
OLTAGE TO ACCELERATION CONVERSION
.......................................................................... 7
2.3.
R
ATIOMETRIC
O
UTPUT
....................................................................................................... 7
2.4.
S
ELFTEST AND FAILURE DETECTION MODES
......................................................................... 7
3.
Mechanical Specification .......................................................................................... 9
3.1.
D
IMENSIONS
...................................................................................................................... 9
4.
Application information ............................................................................................ 10
4.1.
R
ECOMMENDED
PCB
LAY
-
OUT
......................................................................................... 10
4.2.
R
EFLOW SOLDERING
........................................................................................................ 11
SCA620-EF8H1A
Murata Electronics Oy 3/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
1. Electrical Specifications
1.1. Absolute Maximum Ratings
Parameter
Value
Units
Acceleration (powered or non-powered) 20 000
(1
g
Supply voltage −0.3 to +7.0 V
Voltage at input / output pins −0.3 to VDD + 0.3 V
ESD HBM (Human Body Model) ±2 kV
ESD CDM (Charged Device Model) ±500 middle pins
±750 corner pins
V
Temperature range (storage) −50 to +125 °C
Temperature range (operating) −40 to +125 °C
1
Equals to drop from 1 meter on a concrete surface.
1.2. Performance Characteristics
V
DD
= 5.00 V and ambient temperature unless otherwise specified.
KPC
A
)
Parameter
Condition
Min.
Typ
Max.
Units
Measuring range Nominal −1.7 +1.7 g
Supply voltage Vdd 4.75 5.0 5.25 V
<CC> Current consumption Vdd = 5 V; No load 2.5 4.0 mA
Operating temperature −40 +125 °C
Resistive output load Vout to Vdd or Vss 20 kΩ
Capacitive load Vout to Vdd or Vss 20 nF
Min. output voltage; Vdd = 5 V 20k from Vout to Vdd 0 0.25 V
Max. output voltage; Vdd = 5 V 20k from Vout to Vss 4.75 5.00 V
<CC> Offset (Output at 0 g) @ room temperature Vdd/2 V
<CC> Sensitivity @ room temperature 1.2
(0.24*Vdd)
V/g
Offset Error (Output at 0 g) −40 °C...105 °C -100 0 +100 mg
<SC> −40 °C...125 °C −125 0 +125 mg
Sensitivity error −40 °C...105 °C −4 0 +4 %
<SC> −40 °C...125 °C −5 0 +5 %
Linearity error +1g ... -1g range
+1.7g ... -1.7g range
end point fit
−20
-40
+20
+40
mg
mg
Amplitude response −3 dB
B
)
20 50 80 Hz
Ratiometric error Vdd = 4.75 V...5.25 V −2 +2 %
<SC> Cross-axis sensitivity @ room temperature 3.9 %
Output noise From DC...4 kHz 5 mV
rms
Start-up delay Reset and parity check 10 ms
Self test pull down resistor
(Internal)
44 62 80 kΩ
A)
CC= Critical Characteristics. Must be 100% monitored during production
SC= Significant Characteristic. The process capability (Cpk) must be better than 1.33, which allows sample based
testing. If process is not capable the part will be 100% tested
B)
Output has true DC response
SCA620-EF8H1A
Murata Electronics Oy 4/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
1.3. Offset and sensitivity calibration
Vout offset is calibrated in 0g position:
(
)
gVOffset
out
0=
[V]
Nominal offset is Vdd/2:
2
dd
nom
V
Offset =
[V]
Sensitivity is calibrated as:
(
)
(
)
g
gVgV
ySensitivit outout
2
11 −−+
=
[V/g]
Nominal sensitivity is:
2,1=
nom
ySensitivit
[V/g]
1.4. Error calculations
Total error is the allowed maximum error, which include partial error sources. Total error over
lifetime is specified as a sum of offset and sensitivity errors:
ErrorySensitivitErrorOffsetErrorTotal ___
+
=
[mg]
Offset error is specified as:
( )
ySensitivit
V
gVout
ErrorOffset
dd
2
0
_
−
=
[mg]
Sensitivity error percent is specified as:
(
)
(
)
[
]
%100
211
%_ ×
−−−+
=
nom
nom
ySensitivit
ySensitivitggVoutgVout
ErrorySensitivit
Sensitivity error is specified as:
(
)
[
]
ySensitivit
ErrorySensitivitgVoutVout
ErrorySensitivit %_0
_
×
−
=
[mg]
SCA620-EF8H1A
Murata Electronics Oy 5/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
1.5. Supply voltage
Usage of external 100 nF power supply bypass capacitor is recommended.
ASIC start-up should be tolerant to noise between Vdd and GND. Recommended power-up ramp is
presented below.
Parameter
Min
Max
T
1
T
0
+ 0.1 µs
T
2
T
0
+ 100 µs
V
1
−0.3 V 0.5 V
V
2
4.5 V 5.5 V
Supply voltage ramp at startup.
Figure 2. V
DD
Start-up sequence.
T
0
T
1
T
2
supply voltage
V
2
t
V
1
SCA620-EF8H1A
Murata Electronics Oy 6/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
1.6. Electrical Connection
The following is minimum requirement for electrical interface to the SCA620. If over-voltage or
reverse polarity protection is needed, please contact VTI Technologies Oy for application
information.
Usage of external minimum 100 nF power supply bypass capacitor is recommended. Maximum
rise time of V
DD
is 100 ms.
If self-test (Pin 6) is not used it should be left floating.
Pins 1, 2, 3, and 5 are left floating.
Figure 3. Electrical connection of SCA620 component.
Pin #
Pin Name
I/O
Function
Connection on PCB
1 CLK Float / Not connected
2 C1 Float / Not connected
3 MODE Float / Not connected
4 GND Supply Negative supply voltage (VSS) Ground
5 PGM Float / Not connected
6 ST Input Self-test control Float when not used
7 VOUT Output Sensor output voltage Measuring circuit input
8 VDD Supply Positive supply voltage (VDD) Vdd (+5V)
SCA620-EF8H1A
Murata Electronics Oy 7/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
2. Functional description
2.1. Measuring directions
2.2. Voltage to acceleration conversion
Analog output can be transferred to acceleration using the following equation for conversion:
(
)
ySensitivit
gVV
onAccelerati
outout
0−
=
[g]
where: V
out
(0g) = nominal output of the device at 0g position with 5 V supply voltage (ratiometric
output), Sensitivity is the sensitivity of the device and V
out
is the output of the sensor.
2.3. Ratiometric Output
Ratiometric output means that the zero offset point and sensitivity of the sensor are proportional to
the supply voltage. If the SCA6X0 supply voltage is fluctuating the SCA6X0 output will also vary.
When the same reference voltage for both the SCA6X0 sensor and the measuring part (A/D-
converter) is used, the error caused by reference voltage variation is automatically compensated
for.
2.4. Selftest and failure detection modes
To ensure reliable measurement results the SCA6X0 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 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
analog output voltage is forced to go close to ground level (<0.25 V).
The SCA6X0 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
0
g
position
V
out,nom
= 2.5 V
+1
g
position
V
out,nom
= 3.5 V
+
-
-
1
g
position
V
out,nom
= 1.5 V
+
-
SCA620-EF8H1A
Murata Electronics Oy 8/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
to go to the maximum value. The self test function is activated by a separate on-off command on
the self test input.
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 analogue output. Self test can be activated applying logic”1”
(positive supply voltage level) to ST pin (pins 6) of SCA6X0. The self test Input high voltage level is
4 – Vdd+0.3 V and input low voltage level is 0.3 – 1 V.
Figure 7. 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.
T1 [ms] T2 [ms] T3 [ms] T4 [ms] T5 [ms] V2: V3:
10-100 Typ. 20 Typ. 50 Typ. 70 Typ. 10 Min 0.95*VDD
(4.75V @Vdd=5V)
0.95*V1-
1.05*V1
Self test characteristics.
Vout
5V
0 V
T
IME
[
MS
]
T1
T2
T3
T4
V1
V2
V3
ST pin
voltage
0 V
5 V
T5
SCA620-EF8H1A
Murata Electronics Oy 9/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
3. Mechanical Specification
Lead frame material: Copper
Plating: Nickel followed by Gold
Solderability: JEDEC standard: JESD22-B102-C
Co-planarity: 0.1 mm max.
The part weights: ~0.73 g
3.1. Dimensions
Figure 8
.
Mechanical dimensions [mm].
SCA620-EF8H1A
Murata Electronics Oy 10/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
4. Application information
The SCA6X0 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 8
and GND plane must be used. If regulator is placed far from component for example other PCB it
is recommend adding more capacitance between VDD and GND to ensure current drive capability
of the system. For example 470 pF and 1uF capacitor can be used.
The SCA6X0 has a ratiometric output. To get the best performance use the same reference
voltage for both the SCA6X0 and Analog/Digital converter.
Locate the 100nF power supply filtering capacitor close to VDD pin 8. Use as short a trace length
as possible. Connect the other end of capacitor directly to the ground plane. Connect the GND pin
4 to underlying ground plane. Use as wide ground and power supply planes as possible. Avoid
narrow power supply or GND connection strips on PCB.
4.1. Recommended PCB la y-out
Figure 9. Recommended PCB lay-out [mm].
Notes:
• 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.
• 1° mounting alignment error will increase the cross-axis sensitivity by 1.7%
• 1° mounting alignment error will change the output by 17 mg
• Wave soldering is not recommended
• Ultrasonic cleaning is not allowed
• A supply voltage by-pass capacitor (> 100 nF) is recommended
SCA620-EF8H1A
Murata Electronics Oy 11/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
4.2. Reflow soldering
The SCA6X0 is suitable for Sn-Pb eutectic and Pb- free soldering process and mounting with
normal SMD pick-and-place equipment. Recommended body temperature profile during reflow
soldering:
Figure 10.
Recommended body temperature profile during reflow soldering. Ref.
IPC/JEDEC J-STD-020D.
Profile feature Sn-Pb Eutectic
Assembly
Pb-free Assembly
Average ramp-up rate (T
L
to T
P
) 3 °C/second max. 3 °C/second max.
Preheat
- Temperature min (T
smin
)
- Temperature max (T
smax
)
-
Time (min to max) (ts)
100 °C
150 °C
60-120 seconds
150 °C
200 °C
60-180 seconds
Tsmax to T
L
- Ramp up rate
3°C/second max
Time maintained above:
- Temperature (T
L
)
- Time (t
L
)
183 °C
60-150 seconds
217 °C
60-150 seconds
Peak temperature (T
P
) 240 +0/−5 °C 250 +0/−5 °C
Time within 5 °C of actual Peak Temperature
(T
P
)
10-30 seconds 20-40 seconds
Ramp-down rate 6 °C/second max 6 °C/second max
Time 25 °C 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-020D. The
part should be delivered in a dry pack. The manufacturing floor time (out of bag) in the
customer’s end is 168 hours.
SCA620-EF8H1A
Murata Electronics Oy 12/12
www.muratamems.fi Doc. nr. 82 1643 00 Rev.B
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
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. Maximum soldering temperature is
250 °C/40 sec.
Rework after the initial soldering process is not recommended. Rework can cause heat
build-up to the leg and this heat build-up will cause the housing material to get soft
thus allowing the leg to move. The movement can cause bond wire disconnection
inside the part.
