Diodes Incorporated AH9251-P-B

Overview

AH9251-P-B from Diodes Incorporated is a medium-sensitivity, micropower omnipolar Hall-effect switch in TO92S package with built-in pull-up resistor, chopper stabilization, and sleep-awake logic. It operates from 2.5V to 5.5V, draws 4µA typical sleep current and 8µA average current at 3V, and switches on with either north or south magnetic pole - ideal for battery-powered lid detection and proximity sensing in industrial handhelds.

For engineers reviewing the AH9251-P-B datasheet, AH9251-P-B pinout, AH9251-P-B application, or AH9251-P-B equivalent, key selection criteria include magnetic operating point (BOP = ±40–80 G), hysteresis (10 G), temperature stability (–40°C to +85°C), SC59/TO92S package compatibility, and micropower sleep mode timing (100 ms sleep, 150 µs awake).

Technical Context

The AH9251 employs a chopper-stabilized Hall plate and comparator architecture to suppress offset drift across voltage and temperature, ensuring stable BOP/BRP switching thresholds. Its sleep-awake control logic cycles between active sensing (150 µs awake) and latched-output low-power state (100 ms sleep), achieving 8 µA average supply current at 3V.

Magnetic response is omnidirectional: output turns low when perpendicular flux density exceeds ±40–80 G (BOP), and returns high below ±30–70 G (BRP), delivering 10 G hysteresis. The digital open-drain output includes an internal 100 kΩ pull-up and supports 1 mA sink capability with 0.4 V saturation voltage.

Key Specifications

Pinout & Package

Package: TO92S (3-pin, through-hole, industry-standard plastic package with 1.27 mm lead pitch and 14–15.5 mm body length).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AL3301E-13 and US1881LUA-AB3-B, the AH9251-P-B uniquely balances omnipolarity, integrated pull-up, TO92S fit, and 8 µA average consumption - making it optimal for mechanically constrained, battery-powered systems requiring polarity-agnostic actuation.

Availability

AH9251-P-B is available at Aetrix Electronics and suitable for laptop lid detection, smart appliance door sensing, industrial equipment cover monitoring, and battery-powered IoT sensor node applications requiring stable component supply, long-life micropower operation, and through-hole manufacturability.

Supply support for AH9251-P-B 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 manufacturer of discrete semiconductors and analog ICs, serving industrial, computing, consumer, and communications markets with high-reliability, RoHS-compliant components.

The AH9251 belongs to Diodes' Hall-effect switch product line, engineered specifically for ultra-low-power, magnetically actuated status sensing in portable and energy-constrained systems - emphasizing stability, ease of integration, and qualification across extended temperature ranges.

FAQ

What is the magnetic polarity requirement for AH9251-P-B operation?

The AH9251-P-B is an omnipolar Hall switch: it activates with either the north or south pole of a magnet oriented perpendicular to the part marking surface. BOPN is –80 to –40 G (north pole), and BOPS is +40 to +80 G (south pole); both turn the output low. No magnet orientation setup is needed during assembly.

Can AH9251-P-B drive an LED directly?

No - the AH9251-P-B output is open-drain with 1 mA maximum sink current and 0.4 V saturation voltage. It cannot source current or drive LEDs directly. To light an LED, connect the anode to VDD and cathode to OUTPUT; the LED will illuminate when the output is low (magnet present), but current must be limited to ≤1 mA via series resistor.

Is external decoupling required for stable operation?

Yes - the datasheet specifies a 10 nF ceramic capacitor between VDD and GND, placed as close as possible to the device pins. This stabilizes the internal bias circuitry during the 150 µs awake period and prevents false triggering caused by supply transients or noise coupling.

How does temperature affect the magnetic switching points?

BOP and BRP vary with temperature: at –40°C, BOP shifts ~–10 G; at +85°C, it shifts ~+10 G relative to 25°C values. Full-range min/max specs (e.g., BOP = ±40–80 G) already include this variation. Chopper stabilization minimizes drift, but system-level margin should account for ±10 G shift across the operating range.