Variable Reluctance Sensor Interfaces With Differential Input And Adaptive Peak Threshold

The MAX9924 MAX9925 MAX9926 MAX9927 variable reluctance (VR or mag- netic coil) Sensor Interface devices are ideal for position and speed sensing for automotive crankshafts, camshafts, transmission shafts, etc. These devices inte- grate a Precision Amplifier and Comparator with selectable adaptive peak threshold and zero-crossing circuit blocks that generate robust output pulses even in the presence of substantial system noise or extremely weak VR signals. The MAX9926/MAX9927 are dual versions of the MAX9924 MAX9925, respectively. The MAX9924 MAX9926 combine matched resistors with a CMOS input precision Operational Amplifier to give high CMRR over a wide range of input frequencies and temperatures. The MAX9924 MAX9926 Differential Amplifiers provide a fixed gain of 1V/V. The MAX9925/MAX9927 make all three ter- minals of the internal Operational Amplifier available, allowing greater flexibility for gain. The MAX9926 also provides a direction output that is useful for quadrature- connected VR Sensors that are used in certain high-per- formance engines. These devices Interface with both new-generation differential VR Sensors as well as legacy single-ended VR Sensors The MAX9924 MAX9925 are available in the 10-pin MAX package, while the MAX9926/MAX9927 are available in the 16-pin QSOP package. All devices are specified over the -40C to +125C automotive temper- ature range. By Maxim Integrated Products