Diodes Incorporated ZMT31TA

Overview

ZMT31TA from Zetex Semiconductors is a contactless angular position sensor IC based on dual Wheatstone bridge architecture for measuring rotation angle and direction of a rotating permanent magnet. It delivers sinusoidal output signals proportional to sin²(θ) and sin²(θ+45°), supports 0–360° absolute angle determination, operates at 5 V supply, and is rated for −25°C to +130°C ambient temperature - used in water meter revolution counting and automotive pedal position sensing.

For engineers reviewing the ZMT31TA datasheet, ZMT31TA pinout, ZMT31TA application, or ZMT31TA equivalent, key selection considerations include magnetic field sensitivity (≥50 kA/m), bridge offset voltage (±2 mV/V), temperature coefficient of sensitivity (−0.35 to −0.25 %/K), and SM-8 package compatibility with automated SMT placement.

Technical Context

The ZMT31TA integrates two matched Wheatstone bridges oriented at 45° relative to each other on a single silicon die, enabling differential phase-based angle decoding. Each bridge produces a voltage output referenced to VB/2, with zero-crossing detection used for revolution counting and quadrature signal comparison for direction resolution.

Bridge resistance is trimmed to 2.0–4.0 kΩ per leg, and output voltage range is ±8 mV/V (16 mV/V total span) under full-scale magnetic field excitation. The device requires no external calibration and maintains <2° sensor alignment error across its operating temperature range.

Key Specifications

Pinout & Package

Package: SM-8 (8-pin surface-mount package, 6.3 × 3.5 mm body, 1.7 mm height, 12 mm tape width, 1000 units per reel).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar angular position sensing applications.

Compared with AS5055-BSST and TLE5012B E1000, the ZMT31TA offers analog quadrature outputs for direct interfacing with low-cost MCUs lacking dedicated angle peripherals, retains full temperature performance down to −25°C without internal compensation, and supports simple 5 V supply architecture - making it optimal for cost-sensitive industrial metering and non-safety-critical motion sensing.

Availability

ZMT31TA is available at Aetrix Electronics and suitable for water metering, automotive pedal position sensing, and contactless rotary switch applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ZMT31TA 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

Zetex Semiconductors (now part of Diodes Incorporated) specialized in high-performance analog and mixed-signal ICs for precision sensing, power management, and interface applications before acquisition in 2008.

The ZMT series was developed specifically for contactless angular and rotational position sensing in harsh environments - emphasizing magnetic immunity, wide temperature operation, and analog output compatibility with legacy control systems.

FAQ

What is the minimum required magnetic field strength for reliable ZMT31TA operation?

The ZMT31TA requires a rotating magnetic field with flux density ≥50 kA/m (≈6.3 mT) parallel to the chip surface. This threshold ensures sufficient signal-to-noise ratio for accurate zero-crossing detection and angle decoding. Fields below this level produce outputs within noise floor and may cause missed counts or angle ambiguity.

Can ZMT31TA be used with a 3.3 V supply instead of 5 V?

No - the ZMT31TA is specified only for 5 V supply (VB = 5 V). Its bridge resistances, offset voltages, and sensitivity values are characterized and trimmed at 5 V. Operating at 3.3 V reduces output amplitude proportionally, degrades SNR, and violates the absolute maximum ratings for bridge biasing, risking inaccurate angle measurement or device instability.

How is direction of rotation determined using ZMT31TA outputs?

Direction is determined by comparing the phase relationship between Bridge 1 (sin²θ) and Bridge 2 (sin²(θ+45°)) outputs. When θ increases (clockwise), Bridge 2 leads Bridge 1; when θ decreases (counterclockwise), Bridge 1 leads Bridge 2. Standard quadrature decoding logic or cross-zero timing analysis extracts direction from this 45° phase offset.

Does ZMT31TA require external calibration or trimming components?

No external calibration or trimming components are required. The device features factory-trimmed bridge resistances, offset voltages, and half-bridge symmetry. All specifications - including ±2 mV/V offset and 0.2 (mV/V)/° sensitivity - are guaranteed over temperature without user adjustment, enabling drop-in use in production designs.