Diodes Incorporated AH1381-FS4-7

Overview

AH1381-FS4-7 from Diodes Incorporated is a high-sensitivity, ultra-low-power digital unipolar Hall-effect switch IC designed for magnetic proximity detection in battery-constrained systems. It operates with 1.6V–5.5V supply, draws only 1.6μA average current at 3V, and switches on with south-pole magnetic fields ≥18G (typical BOPS), making it ideal for smart cover detection in portable electronics and smoke detector status sensing.

For engineers reviewing the AH1381-FS4-7 datasheet, AH1381-FS4-7 pinout, AH1381-FS4-7 application, or AH1381-FS4-7 equivalent, this device requires attention to its X2-DFN1010-4 (Type B) package footprint, NC pin handling, chopper-stabilized temperature stability, and unipolar south-pole activation threshold in low-noise, low-power system integration.

Technical Context

The AH1381-FS4-7 implements a chopper-stabilized Hall sensor with hibernating clocking architecture, enabling ultra-low quiescent current while maintaining ±7G hysteresis (BHY) and <±7G total switch-point drift over –40°C to +85°C. Its internal latch and output driver deliver rail-to-rail switching without external pull-up resistors.

It features a dedicated sleep/awake logic block that cycles between 45ms typical sampling periods (tPERIOD) and 45μs wake time (tAWAKE), achieving 0.1% duty cycle to minimize average power. The output is open-drain, sinking up to 1mA with VOL ≤0.25V at 1mA load.

Key Specifications

Pinout & Package

Package: X2-DFN1010-4 (Type B), 1.0mm × 1.0mm × 0.39mm body, exposed thermal pad (no internal connection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with A3212LLHLT-T and US1881EUA-ABA-002-SP, AH1381-FS4-7 delivers the lowest average current (1.6μA) in the smallest footprint (1.0mm²), making it optimal for next-gen wearables and sealed battery devices where size and multi-year runtime are primary constraints.

Availability

AH1381-FS4-7 is available at Aetrix Electronics and suitable for smart cover detection, lid position sensing, and smoke detector status monitoring requiring stable component supply across high-mix, low-volume production runs.

Supply support for AH1381-FS4-7 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 company specializing in discrete, analog, and mixed-signal ICs for power management, signal integrity, and sensing applications.

AH1381-FS4-7 belongs to Diodes' Hall-effect switch product line, engineered specifically for ultra-low-power magnetic sensing in battery-operated consumer and industrial endpoints.

FAQ

What is the magnetic polarity requirement for AH1381-FS4-7 activation?

The AH1381-FS4-7 activates exclusively with the south pole oriented toward the marked side of the package. Its unipolar response ignores north-pole fields entirely. The typical operate point is 18 Gauss, with release occurring below 11 Gauss - verified across –40°C to +85°C and 1.6V–5.5V supply range per DS44734 Rev. 2–2.

Can the NC pin on the X2-DFN1010-4 package be grounded?

Yes, Pin 3 (NC) has no internal connection and may be tied to GND for mechanical reinforcement or left floating. Diodes explicitly states in DS44734 that NC pins "can be left open or tied to ground" with no electrical impact on performance, timing, or reliability.

Does AH1381-FS4-7 require an external decoupling capacitor?

Yes - a 100nF ceramic capacitor is mandatory between VDD and GND, placed as close as possible to the pins. This stabilizes the internal regulator during wake cycles and strengthens RF noise immunity, as specified in the Typical Applications Circuit and Layout Guidelines section of DS44734.

How does the hibernating clock affect system responsiveness?

The hibernating clock imposes a fixed 45ms typical sampling period (tPERIOD), meaning the output updates no faster than once every 45ms. However, tAWAKE is only 45μs - so once triggered, the output asserts within microseconds. This trade-off prioritizes energy savings over real-time response, appropriate for cover/lid detection but not for high-speed rotation counting.