Integrated magnetic field detector circuit, e.g. Hall effect switch, for motor vehicle

摘要

The circuit has a magnetic field/voltage converter (22) with its output fed to a comparator (24) with a hysteresis characteristic which generates a binary output signal of one type if its input signal exceeds a threshold. A different signal is generated if the converter output and the comparator are connected with one output to an input of the converter. An anti-slosh accumulator (26,28) generates the integral with time of the comparator binary signal if it is of one type including the accumulator signal by a prescribed time during time intervals if it is of the other type. An external DC source (40) in series with an external alarm lamp (38) can be connected to two integrated circuit terminals between which is connected an interlock driver (30) which has an input connected to the accumulator. The driver has an interlock threshold providing a high impedance between the circuit terminal when the accumulator signal is in one binary state and a low impedance if the size of the signal exceeds a preset value.