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Diodes Incorporated AH291-PL-B
- Part No.:
- AH291-PL-B
- Manufacturer:
- Diodes Incorporated
- Category:
- Motor Drivers, Controllers
- Package:
- -
- Datasheet:
-
AH291-PL-B.pdf
- Description:
- IC HALL FAN CTRLR 400MA SIP-4
- Quantity:
- Payment:
- Shipping:
Inventory:720
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Product details
Overview
AH291-PL-B from Diodes Incorporated is a monolithic Hall-effect smart fan motor controller for two-coil BLDC cooling fans, integrating an on-chip Hall sensor, complementary open-collector drivers (DO/DOB), rotor-lock detection, automatic restart, and built-in Zener output protection. It operates from 1.8V to 5.75V, delivers 400mA average output current, and supports SIP-4L and SOT89-5L packages for compact thermal management in low-voltage cooling systems.
For engineers reviewing the AH291-PL-B datasheet, AH291-PL-B pinout, AH291-PL-B application, or AH291-PL-B equivalent, this device is selected for its integrated rotor-lock shutdown timing (TRLP-ON = 0.4s, TRLP-OFF = 2.4–3.6s), low saturation voltage (VSAT = 300mV @ 180mA), and dual-package availability enabling board-level layout flexibility in space-constrained thermal subsystems.
Technical Context
The AH291 implements a Hall-sensing commutation control loop with dedicated lock-detection logic that monitors back-EMF absence and triggers periodic shutdown/restart cycles during rotor stall. Its internal regulator powers the Hall plate and logic while maintaining stable operation across 1.8–5.75V input range.
Complementary DO/DOB outputs drive external fan coils in push-pull configuration, with Zener clamping (Vz = 15V) protecting against inductive kickback. The truth table defines rotating mode (H/L or L/H inputs) and lockup mode (both inputs high), enabling deterministic state-based motor control without external microcontroller intervention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 1.8V to 5.75V - Enables direct interface with 3.3V and 5V logic rails and battery-backed low-voltage systems. |
| Output Current (Avg) | 400mA - Supports typical two-coil BLDC fans up to ~2W mechanical output at 5V. |
| Output Saturation Voltage | 300mV @ 180mA - Minimizes conduction loss and self-heating in driver stage under nominal load. |
| Rotor Lock Off Time | 2.4–3.6s - Defines safe cooldown interval before automatic restart attempt, preventing thermal runaway. |
| Hall Magnetic Sensitivity | Bop = 30–60G, Brp = −60 to −30G - Matches standard ferrite or NdFeB fan magnets with ≥30G hysteresis margin. |
| Power Dissipation (SIP-4L) | 550mW @ 25°C - Sets maximum continuous coil drive capability before thermal derating begins. |
| Operating Ambient Temp | −20°C to +100°C - Validated for industrial-grade cooling applications including enclosed power supplies and network gear. |
Pinout & Package
Available in SIP-4L (4-pin single-inline package) and SOT89-5L (5-pin surface-mount package). SIP-4L provides simplified through-hole mounting; SOT89-5L offers improved thermal performance and PCB area efficiency.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Vdd | Positive supply input | Accepts 1.8–5.75V; powers internal regulator, Hall sensor, and logic - must be decoupled with ≥2.2µF ceramic capacitor. |
| DO | Complementary output driver A | Open-collector NPN output; sinks current to GND when active - drives one fan coil leg with external pull-up. |
| DOB | Complementary output driver B | Open-collector NPN output; phase-inverted relative to DO - enables full-bridge-like commutation with external coils. |
| GND | Ground reference | Common return path for Vdd, DO, DOB, and Hall sensor - requires low-impedance connection to minimize noise coupling. |
| NC (SOT89-5L only) | No-connect terminal | Internally unconnected; must remain floating - no routing or soldering required on PCB. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip Hall sensor | Eliminates external magnetic sensing components and alignment tolerances - reduces BOM count and assembly complexity. |
| Rotor-lock shutdown | Detects stalled condition via missing Hall transitions and disables outputs within 0.4s - prevents coil burnout during jammed operation. |
| Automatic restart | Re-enables drive after fixed 2.4–3.6s off period - maintains fan readiness without host intervention or firmware polling. |
| Built-in Zener protection | 15V clamp on DO/DOB pins - suppresses inductive voltage spikes from fan windings without external TVS diodes. |
| Green molding compound | RoHS-compliant, halogen-free encapsulation - meets environmental compliance requirements for industrial and consumer end equipment. |
Applications
| Server CPU Cooling Fan | Network Switch Heat Sink Fan |
|---|---|
Use Scenario: Continuous-duty 40mm–60mm BLDC fan mounted on server motherboard near CPU VRM. IC Role / Device Role / Timing Role: Hall-commutated motor controller providing closed-loop rotation feedback and stall recovery without MCU involvement. Use Value: Ensures uninterrupted airflow during thermal throttling events; rotor-lock restart prevents system shutdown due to fan failure. |
Use Scenario: Compact 30mm fan cooling ASIC heat sink in Layer-3 enterprise switch chassis. IC Role / Device Role / Timing Role: Low-voltage (3.3V) motor driver with integrated Hall sensing and Zener-protected outputs for reliable operation in dense PCB layouts. Use Value: Reduces component count vs. discrete Hall + driver solutions; 100°C ambient rating supports sealed, fan-filtered enclosures. |
| Industrial PLC Cabinet Fan | Medical Diagnostic Power Supply Fan |
Use Scenario: 50mm fan circulating air inside IP54-rated programmable logic controller cabinet operating in factory environments. IC Role / Device Role / Timing Role: Ruggedized motor controller with −20°C to +100°C operation and lock-protection cycling for dust-prone installations. Use Value: Eliminates need for external watchdog circuitry; automatic recovery restores cooling after temporary debris blockage. |
Use Scenario: Low-noise 25mm fan cooling switching power supply in ultrasound or MRI auxiliary power unit. IC Role / Device Role / Timing Role: Hall-based commutation controller ensuring precise speed regulation and silent operation via smooth torque delivery. Use Value: On-chip Hall sensor avoids EMI-sensitive external sensors; green compound satisfies medical RoHS and material disclosure requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Hall-effect BLDC fan motor controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ALLEGRO A3921KLPTR-T | Higher supply range (4.5–40V), higher peak current (1.5A), but no integrated Hall sensor - requires external magnet and sensor. | Targeted at 12V/24V industrial blowers; lacks auto-restart logic and low-voltage capability below 4.5V. | Select when driving larger fans above 5V or requiring higher current; not drop-in for AH291's 1.8–5.75V use cases. |
| ON Semiconductor NCP1701BDR2G | Integrated Hall sensor and lock protection, but limited to 3.3V operation only and 250mA output - no 5V support or Zener clamping. | Suitable only for ultra-low-power 3.3V fans; lacks thermal robustness beyond 85°C ambient. | Choose for cost-sensitive 3.3V-only designs where 400mA and 100°C operation are unnecessary. |
Compared with A3921KLPTR-T and NCP1701BDR2G, AH291-PL-B uniquely combines sub-2V startup, dual-package flexibility, integrated Hall sensing, and Zener-protected 400mA outputs - making it optimal for compact, low-voltage, self-recovering cooling systems where BOM reduction and thermal resilience are critical.
Availability
AH291-PL-B is available at Aetrix Electronics and suitable for server CPU cooling, network switch thermal management, industrial PLC cabinet ventilation, and medical diagnostic power supply fans requiring stable component supply and long-lifecycle support.
Supply support for AH291-PL-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 high-reliability power management, signal integrity, and precision sensing solutions for industrial, computing, and communications markets.
AH291 belongs to Diodes' Smart Motor Control product line, designed specifically for cost-effective, self-contained BLDC fan control in space- and power-constrained thermal subsystems - emphasizing integration, stall resilience, and RoHS compliance.
FAQ
What is the minimum supply voltage required for reliable Hall sensor operation in AH291-PL-B?
The AH291-PL-B begins switching outputs at Vdd ≥ 1.8V, but magnetic sensing functionality (Bop/Brp) only stabilizes above 2.0V per datasheet Note 2. Below 2.0V, rotor position detection may be inconsistent, risking erratic commutation or missed lock detection. Designers must ensure stable ≥2.0V rail during startup and operation.
Can AH291-PL-B drive a three-phase BLDC fan?
No - AH291-PL-B provides only two complementary open-collector outputs (DO and DOB) intended for two-coil (bipolar) BLDC fan topologies. It lacks the third output channel and associated commutation logic required for true three-phase operation. Using it with a three-phase fan would result in incomplete excitation and non-rotating or jittering behavior.
How does the rotor-lock protection cycle behave under continuous blockage?
Under sustained rotor blockage, AH291-PL-B executes a repeating cycle: 0.4s ON (output active), then 2.4–3.6s OFF (outputs disabled). This fixed-duration off-time allows coil cooling before each restart attempt. The cycle continues indefinitely until mechanical obstruction is removed, preventing cumulative thermal damage.
Is the NC pin on the SOT89-5L package electrically isolated or internally tied?
The NC pin on the SOT89-5L package is internally unconnected - no bond wire or silicon node links to it. Per datasheet Pin Descriptions and marking diagrams, it must remain unconnected on PCB layout. Soldering or routing to this pin risks shorting adjacent terminals or compromising thermal pad integrity.
AH291-PL-B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- -
- Function:
- -
- Output Configuration:
- -
- Interface:
- -
- Technology:
- -
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- -
- Voltage - Supply:
- -
- Voltage - Load:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
AH291-PL-B FAQ
1.How can I place an order for AH291-PL-B through Aetrix?
Please submit a Request for Quotation (RFQ) for AH291-PL-B on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AH291-PL-B reliable?
The price and inventory of AH291-PL-B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AH291-PL-B is usually 5 days.
3.What payment methods are accepted for AH291-PL-B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AH291-PL-B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AH291-PL-B?
AH291-PL-B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AH291-PL-B order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AH291-PL-B?
For technical support, including AH291-PL-B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AH291-PL-B requirements.
6.How does Aetrix verify that AH291-PL-B is sourced from the original manufacturer or authorized distributors?
All AH291-PL-B products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AH291-PL-B meets industry standards.
7.What is the process for return or replacement of AH291-PL-B?
All AH291-PL-B units undergo pre-shipment inspection (PSI). If there is an issue with AH291-PL-B, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AH291-PL-B part is unused and in its original packaging.
Return procedure for AH291-PL-B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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