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A1360_V Datasheet(PDF) 13 Page - Allegro MicroSystems |
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A1360_V Datasheet(HTML) 13 Page - Allegro MicroSystems |
13 / 26 page ![]() A1360, A1361, and A1362 Amp Regulator Clock/Logic Hall Element Low-Pass Filter When using Hall-effect technology, a limiting factor for switchpoint accuracy is the small signal voltage developed across the Hall element. This voltage is disproportionally small relative to the offset that can be produced at the output of the Hall device. This makes it difficult to process the signal while maintaining an accurate, reliable output over the specified oper- ating temperature and voltage ranges. Chopper stabilization is a unique approach used to minimize Hall offset on the chip. The patented Allegro technique, namely Dynamic Quadrature Offset Cancellation, removes key sources of the output drift induced by thermal and mechanical stresses. This offset reduction technique is based on a signal modulation- demodulation process. The undesired offset signal is separated from the magnetic field- induced signal in the frequency domain, through modulation. The subsequent demodulation acts as a modulation process for the offset, causing the magnetic field-induced signal to recover its original spectrum at base band, while the dc offset becomes a high-frequency signal. The magnetic-sourced signal then can pass through a low-pass filter, while the modulated dc offset is suppressed. The chopper stabilization technique uses a 210 kHz high frequency clock. For demodulation process, a sample and hold technique is used, where the sampling is performed at twice the chopper frequency (420 kHz). This high-frequency operation allows a greater sampling rate, which results in higher accuracy and faster signal- processing capability. This approach desensitizes the chip to the effects of thermal and mechanical stresses, and produces devices that have extremely stable quiescent Hall output voltages and precise recoverability after temperature cycling. This technique is made possible through the use of a BiCMOS process, which allows the use of low-offset, low-noise amplifiers in combination with high-density logic integration and sample-and-hold circuits. Concept of Chopper Stabilization Technique Typical Application Drawing Chopper Stabilization Technique GND VOUT FILTER A136x VCC V+ 0.1 μF CBYPASS CFILTER CL Low-Noise Programmable Linear Hall Effect Sensor ICs with Adjustable Bandwidth (50 kHz Maximum) and Analog Output 13 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com |
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