Automotive Electronics
High-g accelerometers
for passive safety applications
SMB18x, SMB19x
Overview
The SMB18x and SMB19x sensor modules are designed for
automotive airbag systems. Main application of these
sensor modules are peripheral acceleration sensors for
front or side crash sensing. Other applications like e.g.
shock monitoring are also possible.
The sensor consists of a micromechanical (MEMS) sensor
element and a signal processing ASIC packaged together in
a molded plastic housing for surface mounting.
Product description
Acceleration sensor SMB18x for airbag applications
Customer benefit / features:
The SMB18x and SMB19x sensors are linear, in-plane,
single
channel
(ax)
accelerometers
available
with
a
measurement range of ±100 g or ±200 g.
 Single (ax) channel accelerometers
An
 Digital transmission of acceleration data via 2-wire
electronics and the high signal stability over temperature
current interface (PAS4 protocol, 8 bit)
embedded
full
self-tests
of
the
mechanics
and
and lifetime provide highly reliable data for safety critical
 On-chip 400 Hz 3-pole Bessel filter
applications. A 2-wire current interface with 8 bit is used
 Full power-on self-test of sensor and ASIC
(PAS4 – Peripheral Acceleration Sensor protocol) for data
 Automatic offset adjustment
transmission.
 Small number of external components required
 Serial part number transmittable
All acceleration sensors are applicable in the temperature
 RoHS compliant
range from -40 °C...+85 °C. Higher temperatures up to
+120 °C are possible for the SMB190 (±200 g)
The sensors are shipped fully calibrated in a self-contained
SMD-housing.
Automotive Electronics | SMB18x, SMB19x
Working principle
Products
Type
Range
Sens. axes
Sensitivity
SMB180
±100 g
X
1 LSB/g
SMB190
±200 g
X
0.5 LSB/g
The SMB18x/19x accelerometers are manufactured by
using surface micromachining technology. The acceleration
sensors feature suspended free moving comb-like seismic
mass elements and fixed counter-electrodes. As a result of
external forces acting on the vehicle, deflections of the
seismic masses along the sensitive axis generate changes
Parameters SMB18x/19x
Measurement and functional characteristics
Nonlinearity of sensitivity1)
±0.8 %
-3dB corner frequency
400 Hz
Tolerance of sensitivity SMB180
<9%
Tolerance of sensitivity SMB200
< 15 %
Cross axis sensitivity
<5%
Operating conditions
1)
Supply voltage
5 V...11 V
Supply current
< 10 mA
Sink current
< 26 mA
Operating temperature SMB180
-40 °C…+85 °C
Operating temperature SMB190
-40 °C…+120 °C
Typical values
in system capacitance. These changes are detected using
the differential measurement principle.
Interface
The sensors communicates via a 8 bit digital 2-wire current
interface based on the PAS4 (Peripheral Acceleration
Sensor) protocol.
Package
The SMB18x/19x sensors are packaged in easy mountable
state of the art SOIC16-wide packages.
Portfolio
The SMB18x/19x sensors are part of a larger sensor
portfolio. This portfolio consists of acceleration sensors,
angular rate sensors, pressure sensors, torque sensors, and
Outline SOIC16w package
CO2 sensors for occupant safety systems, Vehicle Dynamics
Control
VDC,
active
suspension
systems,
motor
management, steering systems, and A/C systems.
Bosch has been active in the field of micromechanics
(MEMS) for more than 20 years, and is established as one
of the pioneers of this technology. With more than
900 MEMS patents, hundreds of engineers in this field, and
more than 1.6 billion MEMS sensors shipped to date,
Bosch is the global market leader for MEMS sensors.
For more information about automotive MEMS sensors,
visit www.bosch-sensors.com.
Dimensions in millimeters
Regional sales
Europe/Japan
USA/Canada
China
Korea
contacts
bosch.semiconductors@de.bosch.com
bosch.semiconductors@us.bosch.com
bosch.semiconductors@cn.bosch.com
bosch.semiconductors@kr.bosch.com
www.bosch-semiconductors.com
www.bosch-sensors.com
Robert Bosch GmbH
AE/MKT-S
Postfach 13 42
72703 Reutlingen
Germany
www.bosch.de
© Robert Bosch GmbH 04/2011. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications
for industrial property rights. The information provided is for information purposes only and does not constitute a legal obligation or a warranty, express or implied,
concerning quality, marketability or suitability for a specific purpose. The designs incorporated in vehicles and the performance of the designs may vary depending on
the vehicle manufacturer's specifications and requirements for the product. We reserve the right to make product changes, adaptations and modifications without prior
notice.