The aim is to replace pairs of accurately-spaced single Hall sensor ICs with a single new IC, called MLX92253, that uses precision angles to replace precision spacing – it has two sensors at 90° to each other inside.
“At present, engineers using a dual latch solution for stepper or dc motor applications are integrating two discrete solutions or a pitch dependent solution,” said the company. “MLX92253 distinguishes itself by featuring two hall plates, one z-axis and one x-axis, with two independent signal tracks. It also has a common magnetic center, which ensures a quadrature [consistent 90°] phase shift between the two speed outputs, independent of the magnet pole pitch. Furthermore, [it] features a low and narrow magnetic threshold, allowing for smaller magnets or a larger air gap.”
To put some numbers on the claims above, the magnetic thresholds are typically ±1.5mT for both axis, but always somewhere in the range ±0.2 to ±2.8mT. If the +ve threshold is different from the -ve threshold, they are always within 1.7mT of each other, and the same applies between channels (if Electronics Weekly is reading the data sheet right – do check for yourself if this is important to you).
Peak-to-peak output jitter is 5µs over 1,000 switching events when fed with a 10kHz magnetic triangle wave peaking at ≥30mT.
When subjected to a ≥10mT triangle wave, the devices will always work up to 40kHz, and typically to 66kHz.
As these are latching sensors, they hold their last state when the magnetic field is removed.
When power is applied, the outputs are briefly configured as inputs to allow a host MCU to set the device into a known state. “The startup feed-back function allows a microcontroller to retrieve the previous state of the MLX92253 before power-down, ensuring that no movement is missed,” said Melexis.
Operation is over 2.7 to 5.5V (5mA typ) and -40 to 150 ̊C, and the parts are AEC-Q100 qualified for automotive use.
Packaging is ~3 x 3mm surface-mount TSOT-5L, and a single-in-line through-hole VA version is in the pipeline.
Applications are expected in motorised vehicle windows, seats and tailgates, and in e-bikes to detect pedalling cadence, and in window blinds and ventilation systems.
Discover more on this MLX92253 web page
