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CN0332 is a single-supply low cost, high-speed magnetoresistive (MR) signal conditioner with a minimum PCB footprint. The complete signal conditioning solution amplifies the small output voltage of the magnetoresistive sensor and converts it into a digital output signal with a rise and fall time of less than 5 ns and an rms jitter of approximately 100 ps. The circuit provides a compact and cost effective robust solution for high speed rotational sensing in industrial and automotive applications and is an excellent alternative to Hall effect sensors.
The AA747 Sensitec MR Sensor has a typical bridge output voltage of 30 mV p-p to 100 mV p-p at a common-mode voltage that is equal to one-half the supply voltage. The bridge output impedance is approximately 3 kΩ
The ADA4897-2 dual op amp has a high bandwidth (230 MHz for G = +1) and a rail-to-rail input and output making it an ideal buffer for the sensor signal. Voltage noise is only 1 nV/√Hz.
The AD8027 is also a high bandwidth (190 MHz, G = +1) rail-to-rail amplifier with a slew rate of 100 V/μs. It is stable at high gains and is ideally suited to be configured as a difference amplifier of the small signal output of magnetoresistive sensors.
The ADCMP601, a very fast single supply rail-to-rail TTL/CMOS comparator with a propagation delay of only 3.5 ns and a minimum pulse width of 3 ns, converts the amplified small signal voltage to a digital signal.
The ADP1720 low dropout linear regulator is used to isolate the circuit from noise that can occur in harsh environments.
The CN0332 needs a single +5.5 V up to +28 V power supply input and has a PMOD interface.
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