Monolithic Power Systems Inc. EVKT850-KNOB-Q-01A

Overview

EVKT850-KNOB-Q-01A from Monolithic Power Systems is a pre-assembled rotary knob evaluation kit designed for the MA850 MagAlpha magnetic angle sensor. It features an end-of-shaft aluminum shaft with a diametrically magnetized NdFeB cylinder magnet (5 mm Ø × 2.5 mm H, Br = 1.2 T), 0.7 mm and 2.0 mm spacers to adjust air gap (1.5 mm → 3.5 mm), and full compatibility with the EVKT-MACOM communication interface kit for SPI-based sensor characterization including noise, refresh rate, power-up time, and magnetic field dependence.

For engineers reviewing the EVKT850-KNOB-Q-01A datasheet, EVKT850-KNOB-Q-01A pinout, EVKT850-KNOB-Q-01A application, or EVKT850-KNOB-Q-01A equivalent, this kit enables rapid functional validation of MagAlpha MA850 in knob-based human-interface systems requiring precise angular position sensing, programmable zero-point adjustment, and low-field performance testing down to 25 mT.

Technical Context

The EVKT850-KNOB-Q-01A implements Type 2 board architecture optimized for the MA850 sensor, supporting SPI serial interface (CS, SCLK, MOSI, MISO) and six configurable I/O pins (IO1–IO6). It integrates a 1 µF VDD bypass capacitor and provisions for optional 100 nF decoupling at CN1.

Its mechanical design fixes the sensor-to-magnet air gap at 1.5 mm nominal (75 mT), with spacer options enabling controlled reduction to 2.2 mm (50 mT) or 3.5 mm (25 mT) to evaluate sensor linearity and noise under weakened magnetic fields - critical for robustness validation in real-world knob assemblies.

Key Specifications

Availability

EVKT850-KNOB-Q-01A is available at Aetrix Electronics and suitable for industrial HMI development, consumer appliance knob integration, and automotive HVAC control prototyping requiring stable component supply and repeatable magnetic test conditions.

Supply support for EVKT850-KNOB-Q-01A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance power management and sensing solutions, with global manufacturing and quality certifications including ISO 9001 and AEC-Q200 qualified products.

This kit belongs to MPS's MagAlpha magnetic position sensor evaluation platform, engineered specifically to accelerate development of contactless rotary controls in space-constrained, EMI-sensitive applications where potentiometer replacement and field immunity are critical.

FAQ

What sensor IC does EVKT850-KNOB-Q-01A evaluate?

It evaluates the MA850 MagAlpha magnetic angle sensor - a 14-bit, SPI-output, monolithic Hall-effect sensor optimized for end-of-shaft rotary position sensing with built-in diagnostics and programmable zero-point calibration. The board is designated Type 2 per MPS documentation and matches the MA850's pinout and power requirements.

How is magnetic field strength varied on this kit?

Magnetic field strength is adjusted mechanically using the two included non-magnetic spacers (0.7 mm and 2.0 mm thick). Inserting them between the sensor board and knob increases the air gap from nominal 1.5 mm to 2.2 mm (50 mT) or 3.5 mm (25 mT), enabling systematic evaluation of sensor noise and linearity degradation at low field levels.

Is the knob's zero position adjustable?

Yes - mechanical zero is set by loosening the knob's hex screw (1/16″ Allen key), rotating the knob while holding the shaft via its 2 mm alignment hole, then retightening. Additionally, digital zero offset can be programmed into the MA850's register via SPI, allowing fine-tuned calibration without physical repositioning.

Which interface kit is required to communicate with the MA850 on this board?

The EVKT-MACOM (MagAlpha Communication Interface Kit) is required. It provides USB-to-SPI bridging, firmware GUI, and signal conditioning to interface with the EVKT850-KNOB-Q-01A's CN1 connector (16-pin, 2.54 mm pitch), enabling real-time readout of angle data, diagnostics, and register configuration.

Does this kit include a spare magnet?

Yes - it includes one extra cylinder magnet (NdFeB N35, 5 mm Ø × 2.5 mm H, diametrically magnetized), identical to the one mounted on the knob shaft. This allows users to test alternate mounting configurations or replace magnets degraded by mechanical stress or thermal exposure during extended evaluation.

What is the purpose of the TEST pin on CN1?

CN1 Pin 5 (TEST) is a dedicated diagnostic pin on the MA850 that supports internal self-test modes, including coil test and magnetic field saturation detection. When asserted via the EVKT-MACOM interface, it triggers built-in safety checks and outputs status flags over SPI - essential for functional safety validation in automotive or industrial designs.