William C. Dunn

Accelerometer utilizing an annular mass

An accelerometer in which the seismic mass is formed in the shape of an annulus. The annular shape allows twisting motions as well as displacement of the seismic mass to be sensed and restoring electrostatic forces applied. This allows the supporting spring to be made extremely weak avoiding the mechanical limitations of springs.

Driving and protection of high side NMOS power switches

The design of a full-wave voltage-tripler charge pump for driving high-side NMOS switches that can operate with supply voltage variations from 5 to 50 V is described. The circuits for both simple and complex charge pumps and their limitations are discussed. It is shown that the power switch must be protected from external as well as internal voltages. Described are the protection circuits that are necessary to ensure that the working voltage of the control devices and power switch are not exceeded, particularly when working with inductive loads and against supply line transients.<<ETX>>

Automotive sensor applications

The author looks at the features, approaches and technologies of sensors together with packaging problems and automotive applications. Areas of sensing discussed include piezoresistive sensing; capacitive sensing; pressure sensors; accelerometers; self-test features; and opto sensors.<<ETX>>

Accelerometer Design Considerations

Micromachining technology has been used in low cost pressure sensors for a number of years. However, in other structures such as accelerometers, the devices were fragile, suffered from cross axis sensitivity, and lacked overload protection. Low yields also made the devices very expensive, and not cost effective in many applications. But with the technology being driven by low cost, high volume applications, such as in the automotive industry, new cost effective, and rugged devices are being developed to meet these exacting requirements.