This device is no longer in production. The device should not be purchased for new design applications. Samples are no longer available.
Date of status change: April 30, 2012.
Recommended substitution: For existing customer transition, and for new customers or new applications, contact Allegro Sales.
The A1351 device is a high precision, programmable linear Hall-effect sensor IC with a pulse width modulated (PWM) output. The duty cycle (DC) of the PWM output signal is proportional to an applied magnetic field. The A1351 device converts an analog signal from its internal Hall sensor element to a digitally encoded PWM output signal. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analog output signal. A simple RC network can be used to convert the digital PWM signal back to analog signal.
The BiCMOS, monolithic circuit inside of the A1351 integrates a Hall element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. The dynamic offset cancellation circuits reduce the residual offset voltage of the Hall element. Hall element offset is normally caused by device over molding, temperature dependencies, and thermal stress. The high frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.
An internal filter of approximately 150 Hz is used to achieve 11 bits of output resolution.
Key applications for the A1351 include battery current sensing, exhaust gas return (EGR), throttle position, ride height and seat belt tensioning systems.
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