The ATS667LSG from Allegro MicroSystems Europe is a three-wire, true-zero-speed, gear-tooth sensor IC designed for digital gear-tooth sensing in automotive-transmission applications. The single over-moulded module contains a Hall-effect-sensor IC and a samarium-cobalt magnet. The small package can be incorporated into designs and used in conjunction with gears of various shapes and sizes. The dual-element IC switches in response to differential magnetic signals created by a ferrous target; it contains a compensating circuit to eliminate the detrimental effects of magnet and system offsets. Features such as small-signal lock-out, running-mode gain adjustment and automatic offset adjustment provide vibration and offset immunity. The device also contains scan/IDDQ circuitry to enhance the testability and quality level. Digital processing of the analogue signal provides zero-speed performance that is independent of the air gap, as well as offering dynamic adaptation of device performance to the typical operating conditions found in automotive applications—in particular, reduced sensitivity to vibration effects. The signal processing targets the IC at automotive-transmission use, in particular as it allows vibration immunity and operation with large air gaps, which is a common challenge in this environment. High-resolution peak-detecting digital-analogue convertors and a bounded tracking algorithm set the adaptive switching thresholds of the device. The adaptive hysteresis in the thresholds reduces the negative effects of any anomalies in the magnetic signal that are associated with the targets used in many automotive applications. The SG package is lead-free, with 100% matt tin leadframe plating.
