• Acceleration ranges of ±48 g and ±96 g
• Digital SPI output with 10-bit resolution
• Models for 3.3 and 5 volt operating voltage

Bosch is launching the third generation of its micromechanical acceleration sensors. These are tailored to fit into a vehicle’s central electronic control unit but are smaller, more robust and more flexible than previous generation sensors. One typical application is acceleration measurement in airbag control units. Sample quantities of the new sensors are expected to be ready for delivery at the end of the year.

The SMB46x series is available in three variants, for the ±48 g (SMB 462 and SMB 463) and ±96 g (SMB 460) measuring ranges. The SMB 462 and SMB 463 sensors are designed for an operating voltage of 5 volts, while the SMB 460 unit works at 3.3 volts. Although the sensors can measure acceleration forces biaxially along x and y axes, they are still contained in the small SOIC 14n housing meaning they take up 44mm² less than the SOIC 16w design previously used – saving 43 percent. Other remarkable technical specifications include the very accurate sensor readings: at ±5 percent, this simplifies programming of the control units’ algorithms. With a large range of permissible operating temperatures, from -40º to +150º Celsius, developers are given plenty of scope when deciding where to locate the sensor units.

Bosch has completely redesigned the sensors’ output module. For the first time, the unit transmits a serial, 10 bit-resolution digital signal instead of the more conventional analogue signal. A serial peripheral interface has been integrated on the chip for this purpose. The interface is insensitive to electromagnetic fields and, compared to an analogue variant, is more capable of monitoring current operating status to identify faults. As transmission protocol, developers can use either the Bosch SPI interface – which has proved itself in other micromechanical sensors – or, in the SMB 463 model, the open, manufacturer-independent version of the SPI protocol.

The improved details of the SMB 46x series are a result of the fact that signal-processing on the chip is now consistently digital. This includes an offset compensation, which allows the entire signal range to be used, as well as a self-test function for example. Both of these applications can be controlled via SPI commands, without the need for additional hardware.

Bosch has been manufacturing micromechical acceleration sensors since 1996, and had sold 250 million units by the end of 2005. The first generation, with a PLCC 28 housing, was displaced at the end of 2002 by the second generation, with an SOIC 16w housing.

Further information about Bosch micromechanical sensors can be found at http://www.semiconductors.bosch.de/

Bosch media enquiries:

Chris Wakley / David Eden       
Automotive PR
Tel: +44 (0) 20 7494 8050             
Email: cwakley@automotivepr.com / deden@automotivepr.com

Bosch OE enquiries:

Beverley Daniels
Communications Manager
Robert Bosch Limited
Tel: +44 (0) 1895 878155
Email: beverley.daniels@uk.bosch.com

About Bosch
The Bosch Group is the world’s largest provider of automotive technology to all leading vehicle and component manufacturers. 

In 2005, the company generated automotive sales of €26 billion and employs 158,000 people in this sector.  The key business areas include: fuel injection technology (diesel & petrol); systems for active and passive vehicle safety (brakes, ABS, traction control, ESP, control units for restraint systems); electrical motors, rotating electrics and products for car multimedia.