MAX9924

The MAX9924 variable reluctance (VR or magnetic coil) sensor interface devices are ideal for position and speed sensing for automotive crankshafts, camshafts, transmission shafts, etc. These MAX9924 integrate 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.

Features of the MAX9924 are:(1)differential input stage provides enhanced noise immunity; (2)precision amplifier and comparator allows small-signal detection; (3)user-enabled internal adaptive peak threshold or flexible external threshold; (4)zero-crossing detection provides accurate phase information.The zero-crossing signal provides true timing information for engine-control applications. The zero-voltage level in the VR sensor signal corresponds to the center of the gear-tooth and is the most reliable marker for position/angle-sensing applications. Since the output of the differential amplifier is level-shifted to the BIAS voltage,the zero of the input VR signal is simply BIAS.The comparator output state controls the status of the input switch that changes the voltage at its noninverting input from the adaptive/external threshold level to the BIAS level.

The absolute maximum ratings of the MAX9924 can be summarized as:(1)VCC to GND:.-0.3V to + 6V;(2)power dissipation:707.3mW;(3)storage temp:-65 to +150;(4)operating temp:-40 to 125;(5)all other pins:-0.3V to (VCC + 0.3V);(6)current into all other pins:±20mA.Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.The MAX9924 interfaces with variable reluctance (VR) or magnetic coil sensors. These devices produce accurate pulses aligned with flywheel gearteeth even when the pickup signal is small and in the presence of large amounts of system noise. They interface of MAX9924 with new-generation differential VR sensors as well as legacy single-ended VR sensors.