Microchip — LX330x Inductive Position Sensors

The LX3301A, LX3302A and LX34050 from Microchip are inductive position measurement ICs which interface to target PCB coils, and convert their inductive inputs to accurate linear or rotary position measurement outputs.

Inductive position sensors are growing popular as replacements for Hall sensor-based magnetic position sensors, and for resolvers. Inductive position sensing offers higher accuracy and better noise immunity at an attractive system cost.

Microchip’s latest inductive sensor ICs offer a superior implementation of the technology, offering higher accuracy thanks to their low temperature drift, and better noise immunity because they actively reject stray magnetic interference. Designers also benefit from reduced system cost, as no external magnet is required for the operation of the inductive sensor circuit.

The LX3301A and LX3302A sensors include an integrated oscillator circuit for driving the primary coil of an inductive sensor, along with two independent analog conversion paths for conditioning, converting and processing sine and cosine analog signals from the secondary coils of the sensor. Each path includes an EMI filter, demodulator, anti-alias filter, programmable amplifier, and a 13-bit sigma-delta ADC.

The output from the analog conversion is an accurate, 12-bit signal which represents the movement of the metal target over the PCB coils.

The LX3301A provides its measurement outputs via PWM and analog interfaces. The LX3302A additionally provides SENT and PSI5 as well as PWM and analog interfaces.

Each analog signal path includes a digital calibration capability which enables the complete analog path, including the external sensor coils, to be calibrated during system manufacturing. The calibration information is written to an internal EEPROM resulting in improved production yields, and enabling in-line system upgrades. The LX3301A provides six calibration segments, and the LX3302A provides eight.

The EEPROM is coupled with an internal 32-bit RISC processor to provide programmable digital filtering, fault monitoring, and signal processing options for using the IC in a wide range of applications.

The LX34050 is a PCB-based resolver replacement IC for absolute position monitoring.