Diodes Incorporated AH2984-PG-B

Overview

AH2984-PG-B from Diodes Incorporated is a two-phase Hall-effect smart fan motor controller IC integrating a Hall sensor, dynamic offset correction, and dual complementary open-drain output drivers with internal Zener protection. It operates from 2.5V to 15V, delivers up to 500mA average output current, and features rotor lock detection with automatic restart-designed specifically for driving two-coil BLDC cooling fans in low-voltage thermal management systems.

For engineers reviewing the AH2984-PG-B datasheet, AH2984-PG-B pinout, AH2984-PG-B application, or AH2984-PG-B equivalent, key selection criteria include start-up voltage margin (2.5V min), thermal shutdown behavior (150°C TJ max), Rotor Lock Protection timing (Ton = 0.25s, Toff = 3.25s), and package-specific thermal resistance (SIP-4: θJA = 227°C/W).

Technical Context

The AH2984 implements a closed-loop commutation control architecture using an integrated Hall plate and amplifier to sense rotor position, feeding logic that drives complementary DO/DOB outputs with built-in Zener clamping (24–42V breakdown). Its regulator supplies stable bias to internal circuitry across the full 2.5–15V VDD range.

Rotor Lock Protection monitors back-EMF absence and triggers a timed shutdown (0.25s on, 3.25s off) until rotation resumes; overtemperature shutdown activates at TJ ≥ 150°C. The device includes an internal reverse-blocking diode at VDD and supports both SIP-4 and SOT89-5 packages with validated thermal derating curves.

Key Specifications

Pinout & Package

Available in SIP-4 (4-pin single-inline) and SOT89-5 (5-pin surface-mount) packages. SIP-4 uses pins 1–4 for VDD, DO, DOB, GND; SOT89-5 adds NC on pin 5. Both packages feature exposed thermal pads (SOT89-5) or molded body (SIP-4) optimized for conduction cooling in fan modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar two-phase BLDC fan controller applications.

Compared with A3921KLPTR-T and NCP1701BDR2G, the AH2984-PG-B uniquely integrates Hall sensing, rotor lock recovery, and dual-output drive in one SIP-4 package-reducing component count by 4–6 devices and eliminating layout sensitivity to magnetic field alignment.

Availability

AH2984-PG-B is available at Aetrix Electronics and suitable for server CPU cooling fans, industrial PLC cabinet ventilation, and medical imaging equipment fans requiring stable component supply, long-lifecycle support, and RoHS-compliant green packaging.

Supply support for AH2984-PG-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, specializing in power management, signal integrity, and precision analog solutions for industrial, computing, and consumer markets.

The AH2984 belongs to Diodes' Smart Motor Control product line, engineered specifically for compact, self-contained BLDC fan drivers that eliminate external Hall sensors, protection diodes, and discrete logic-targeting thermal management in space-constrained, high-reliability systems.

FAQ

What is the minimum operating voltage for reliable startup of the AH2984-PG-B?

The AH2984-PG-B guarantees functional startup at 2.5V across its full operating temperature range (−40°C to +105°C). Below this threshold, Hall sensor biasing becomes unstable and rotor lock detection may fail. At 2.5V, typical supply current is 2.0mA, and output drivers deliver reduced but usable current (≥300mA avg) with increased RDS(ON) (1.67Ω typ).

How does Rotor Lock Protection behave during a sustained stall condition?

Upon detecting no Hall transitions for >0.25s, the AH2984-PG-B disables both DO and DOB outputs for 3.25s, then attempts automatic restart. This cycle repeats indefinitely until rotation resumes. During shutdown, supply current drops to <100μA, minimizing self-heating and preventing coil saturation damage.

Can the AH2984-PG-B drive a three-phase BLDC motor?

No-the AH2984-PG-B is strictly a two-phase controller with fixed complementary DO/DOB outputs and Hall-based commutation logic designed for two-coil fan windings. It lacks the third output channel, six-step sequencing logic, or programmable timing required for three-phase motors. Attempting to interface it with three-phase motors results in incomplete commutation and potential driver latch-up.

Is the NC pin on the SOT89-5 package electrically isolated or internally tied?

The NC pin (pin 5) on the SOT89-5 variant is fully electrically isolated-no bond wire connects it to any die structure. It is mechanically present for mechanical stability and thermal pad symmetry but carries no electrical function. PCB layout may leave it unconnected or tie it to GND for mechanical anchoring; neither choice affects device operation.