Monolithic Power Systems Inc. MA850GQ-Z

Overview

MA850GQ-Z from Monolithic Power Systems is an 8-bit contactless magnetic angle encoder with PWM output and dual magnetic threshold detection (MGL/MGH) for push/pull button functionality. It replaces potentiometers in manual HMI controls, delivers absolute angular position via 50 kHz PWM (10–90% duty cycle), supports programmable zero angle and rotation direction, and operates at 3.3 V/12 mA across –40°C to +125°C.

For engineers reviewing the MA850GQ-Z datasheet, MA850GQ-Z pinout, MA850GQ-Z application, or MA850GQ-Z equivalent, this page provides verified technical context, SPI register mapping, magnetic field threshold calibration, PWM timing recovery method, and QFN-16 package layout guidance - all critical for knob interface design, automotive HVAC actuators, and white-goods rotary control integration.

Technical Context

The MA850 employs Spinaxis™ phase-detection architecture-measuring magnetic field angle directly via time-to-digital conversion of sinusoidal Hall signals-eliminating arctangent computation or closed-loop interpolation. Its front-end outputs raw angle data at 1 MHz before digital filtering.

Filtering uses a second-order low-pass transfer function (H(s) = 1/(τ²s² + τs + 1), τ = 0.38/F_cutoff) with F_cutoff = 90 Hz, ensuring <4 ms latency under constant-speed rotation while suppressing mechanical vibration noise. Magnetic thresholds (MGHT/MGLT) are independently programmable in 3-bit steps (26–126 mT) and stored in non-volatile register 6.

Key Specifications

Pinout & Package

MA850GQ-Z is housed in a thermally enhanced QFN-16 (3 mm × 3 mm) package with exposed thermal pad. The pad must be connected to GND for optimal electrical noise immunity, thermal dissipation, and mechanical stability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar contactless angle encoder applications.

Compared with AS5600LST and TLE5012BE1000, MA850GQ-Z uniquely combines 8-bit PWM output, dual magnetic threshold flags, QFN-16 footprint, and 3.3 V/12 mA operation - making it optimal for cost-sensitive, space-constrained, and push-button-integrated rotary interfaces without MCU overhead or safety certification requirements.

Availability

MA850GQ-Z is available at Aetrix Electronics and suitable for automotive HVAC knobs, industrial oven control panels, white goods washing machine dials, and medical infusion pump interfaces requiring stable component supply, long-life contactless sensing, and integrated push/pull button functionality.

Supply support for MA850GQ-Z 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 ICs and intelligent motion sensors, with global manufacturing and quality certifications including ISO 9001 and IATF 16949.

The MagAlpha® product line delivers contactless magnetic position sensing solutions optimized for human-machine interface applications - emphasizing ease of use, programmability, and robustness in harsh thermal and mechanical environments.

FAQ

How is the zero angle calibrated on MA850GQ-Z?

Zero angle is programmed via 16-bit register pair (0x00 and 0x01), where Z[15:0] = 65536 − (a₀ × 65536 / 360). For example, 20° zero requires Z = 61895 (0xF1C7). Calibration is stored in on-chip NVM and automatically loaded at power-on; no external EEPROM or MCU storage is needed.

What causes spurious pulses on the MGL pin, and how are they mitigated?

Random ~1.4 µs pulses occur near 44°, 138°, 224°, and 318° due to internal signal path timing; they appear on both MGL pin and register 27 bit 6. Mitigation includes reading MGL twice with 2–100 µs spacing, using inverted MGH as substitute, or computing corrected MGL = !(MG1L | MG2L) from register 27 bits 1–0.

Can MA850GQ-Z operate with magnets weaker than 30 mT?

Yes, but linearity and resolution degrade: INL increases beyond 1.1°, noise rises above 0.02° RMS, and effective resolution drops below 8 bits. Operation below 30 mT is not guaranteed per datasheet specifications and requires system-level validation for each magnet geometry and air gap.

Why does PWM angle recovery require both t_ON and t_OFF measurement?

Because PWM frequency varies ±8 kHz (42–56 kHz) across temperature and unit-to-unit; measuring only t_ON yields incorrect angle if period drifts. Equation (5) uses t_ON/(t_ON + t_OFF) to normalize for period variation, enabling accurate 0.005°–0.02° RMS recovery independent of oscillator drift.

Is the exposed thermal pad required to be grounded?

Yes - grounding the exposed pad is recommended for optimal electrical noise immunity, thermal dissipation (θ_JA = 50°C/W), and mechanical reliability. While the device functions without it, ungrounded pads increase susceptibility to ESD events and reduce long-term stability in high-temperature environments like automotive under-dash locations.

What SPI modes does MA850GQ-Z support, and how is mode selection handled?

MA850GQ-Z supports SPI Mode 0 (CPOL=0, CPHA=0) and Mode 3 (CPOL=1, CPHA=1) with automatic detection. The sensor samples CS and SCLK idle states at power-up and locks to the detected mode; no configuration register setting is required, and switching modes mid-operation is not supported.

How is magnetic threshold hysteresis implemented in MA850GQ-Z?

Hysteresis is fixed at 6 mT (MagHys) between MGHT and MGLT thresholds and is inherent to the analog front-end comparator design. It prevents chattering during slow field transitions and is temperature-compensated at –600 ppm/°C, ensuring stable push/pull detection across –40°C to +125°C.