Diodes Incorporated AH3724-SA-7

Overview

AH3724-SA-7 from Diodes Incorporated is a high-voltage, bipolar Hall-effect latch IC designed for brushless DC motor commutation and angular position sensing in automotive and industrial systems. It operates from 3.0V to 28V, features open-drain output with 30–55mA current limiting, BOP/BRP of 20–60G / –60––20G (typ), and delivers stable switching over –40°C to +125°C.

For engineers reviewing the AH3724-SA-7 datasheet, AH3724-SA-7 pinout, AH3724-SA-7 application, or AH3724-SA-7 equivalent, key selection criteria include magnetic sensitivity hysteresis (40–120G), chopper-stabilized temperature stability, reverse supply protection (–18V), zener-clamped output, and SOT23 (Type S) package compatibility with standard pick-and-place workflows.

Technical Context

The AH3724-SA-7 implements a chopper-stabilized architecture with dynamic offset cancellation, delivering minimal switch-point drift (<±0.5G/°C typical) and superior immunity to mechanical stress and thermal gradients. Its internal bandgap regulator supplies temperature-compensated bias to all analog blocks, enabling consistent BOP/BRP performance across the full –40°C to +125°C range.

It uses a single-pole latching mechanism: South pole exposure switches the open-drain output low (V_{OUT_ON} ≤ 0.4V @ 20mA), and North pole exposure releases it (I_{OUT_OFF} < 10µA). The output remains latched until polarity reversal crosses the hysteresis band (B_HY = |BOP| – |BRP| = 40–120G), preventing chatter in noisy magnetic fields.

Key Specifications

Pinout & Package

Package: SOT23 (Type S), 3-pin, surface-mount, RoHS-compliant, lead-free, halogen-free "Green" construction. Dimensions: 2.90 × 2.40 × 1.00 mm (L × W × H), pin pitch 0.915 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Hall-effect latch applications.

Compared with AH3724-SA-7, AL3724QSA-7 adds AEC-Q100 qualification overhead without altering functional behavior, while US1881LUA-7 trades 28V capability and integrated protection for lower unit cost-making AH3724-SA-7 optimal for 24V+ industrial and automotive body electronics where robustness is non-negotiable.

Availability

AH3724-SA-7 is available at Aetrix Electronics and suitable for brushless DC motor commutation, RPM measurement, and angular position indexing requiring stable component supply across automotive Tier-1 production, industrial drive manufacturing, and HVAC equipment programs.

Supply support for AH3724-SA-7 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

Diodes Incorporated is a global semiconductor manufacturer specializing in discrete, analog, and mixed-signal solutions for power management, signal integrity, and sensing applications.

The AH372X series targets high-reliability magnetic sensing in harsh environments, with the AH3724 variant optimized for mid-sensitivity (40G/–40G) latching in cost-sensitive yet thermally demanding applications like engine cooling fans and power tool controllers.

FAQ

What is the recommended pull-up resistor value for the AH3724-SA-7 output?

For reliable operation across the full 3.0–28V supply range and temperature extremes, a 1kΩ to 10kΩ pull-up resistor is recommended. At 28V with 55mA output sink, 1kΩ yields ~22.5mA drive current and <0.5V logic-low margin; 4.7kΩ balances power efficiency and rise time (t_R < 0.5µs with 20pF load) in most microcontroller interfaces.

Does AH3724-SA-7 require an external bypass capacitor?

Yes - a 10nF to 100nF ceramic capacitor (X7R, 0603 or larger) must be placed between VDD and GND, as close as possible to the device pins. This stabilizes the internal bandgap regulator, improves noise immunity against RF interference, and prevents false triggering during load transients, especially in motor-drive environments.

Can AH3724-SA-7 operate with magnets oriented perpendicular to the top surface?

No - the AH3724-SA-7 in SOT23 (Type S) package is sensitive to magnetic flux perpendicular to the marked side (part marking surface). For correct operation, the South pole must approach the top surface (marked side) to turn ON; North pole on the same side turns OFF. Mounting orientation must follow the "Part mark S N" diagram in the datasheet.

Is AH3724-SA-7 pin-compatible with other AH372X variants in SOT23?

Yes - all AH372X variants (AH3722, AH3724, AH3725, AH3727) share identical SOT23 (Type S) pinout (VDD-GND-OUTPUT), footprint, and thermal characteristics. Only magnetic thresholds differ; no layout change is needed when upgrading sensitivity for different magnet strengths or air gaps.