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Allegro MicroSystems A5944GEETR-T
- Part No.:
- A5944GEETR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 10-UFDFN Exposed Pad
- Datasheet:
-
A5944GEETR-T.pdf
- Description:
- IC MTRDRV MULTPHS 4.5-5.5V 10DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,835
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Product details
Overview
A5944GEETR-T from Allegro MicroSystems is a three-phase sensorless fan driver IC with sinusoidal drive for low-noise operation, 5 V supply voltage (4.5–5.5 V), 450 mA RMS phase current capability, and PWM speed control input. It targets medium-power cooling fans in industrial and computing systems requiring quiet startup and vibration-sensitive environments.
For engineers reviewing the A5944GEETR-T datasheet, A5944GEETR-T pinout, A5944GEETR-T application, or A5944GEETR-T equivalent, key selection criteria include its 10-pin DFN package with exposed thermal pad, FG speed feedback output, SOFTST-adjustable startup profile, lock detection with auto-restart, and 25 kHz motor PWM frequency.
Technical Context
The A5944GEETR-T implements sensorless BEMF-based rotor position detection using a narrow "window" on phase A modulation to minimize waveform distortion while maintaining precise 120° phase-shifted sinusoidal current generation. Its proprietary algorithm dynamically adapts to motor characteristics across speed ranges.
Startup is open-loop with configurable duration and acceleration rate via SOFTST analog input (0–VREF), followed by closed-loop sinusoidal commutation. Speed regulation uses 9-bit PWM duty measurement (7.5–100% valid range) with internal filtering to reject noise-induced false triggers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Range | 4.5–5.5 V - Ensures stable operation with standard 5 V rail; functional down to 3 V but 5 V recommended for reliable startup. |
| RMS Output Current | 450 mA - Supports medium-power fans without external heatsinking under typical PCB thermal conditions. |
| PWM Input Frequency | 0.1–100 kHz - Compatible with common microcontroller PWM peripherals and allows flexible timing design. |
| Motor PWM Frequency | 25 kHz (typ.) - Enables ultrasonic switching to eliminate audible coil whine in fan applications. |
| FG Output | Open-drain, 1 period per electrical revolution - Provides direct RPM feedback synchronized to motor commutation for closed-loop monitoring. |
| Thermal Shutdown | 165°C (typ.), 20°C hysteresis - Protects against sustained overload or poor PCB thermal design without nuisance tripping. |
| SOFTST Input Range | 0–2.9 V - Selects one of 16 startup profiles via resistor divider; enables tuning for diverse motor inertia and winding resistance. |
Pinout & Package
The A5944GEETR-T is housed in a 10-contact 3 mm × 3 mm DFN package with exposed thermal pad (suffix EJ), Pb-free with 100% matte-tin leadframe plating. The thermal pad must be connected to GND for optimal power dissipation and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FG | Speed output signal | Open-drain feedback aligned to electrical revolution; requires external pull-up for system-level RPM reading. |
| 2 CTAP | Motor common connection | Direct interface to motor center tap; leave unconnected if motor lacks centertap - internal generation not supported. |
| 3 VCC | Input supply | 5 V logic and power rail; decoupling capacitor (1–10 µF) required adjacent to pin for stability. |
| 4 OUTA | Motor terminal A | High-side/low-side driven output; part of three-phase bridge delivering sinusoidal current to motor winding A. |
| 5 GND | Ground reference | Primary return path for power, logic, and thermal pad; must be low-impedance plane connection. |
| 6 OUTC | Motor terminal C | Phase-C output with 120° phase shift relative to OUTA; completes three-phase sinusoidal drive waveform. |
| 7 OUTB | Motor terminal B | Phase-B output with 120° phase shift relative to OUTA; enables balanced torque and minimal vibration. |
| 8 VREF | Analog reference output | 2.8 V (typ.) precision reference for SOFTST divider and external circuit biasing; bypass with 0.1 µF ceramic. |
| 9 SOFTST | Startup parameter select | Analog input (0–VREF) selecting 1 of 16 open-loop startup profiles; sets acceleration rate, duration, and initial demand. |
| 10 PWM | Logic input – speed command | Duty-cycle-controlled speed interface; 7.5–100% valid range; internal 250 kΩ pullup enables 100% speed with open-circuit input. |
| PAD | Exposed thermal pad | Must be soldered to GND plane with ≥4 thermal vias; primary path for heat removal (RθJA = 55°C/W on 2-layer PCB). |
Key Features
| Feature | Design Value |
|---|---|
| Sinusoidal drive waveform | Reduces audible noise and mechanical vibration by eliminating trapezoidal current harmonics in fan motors. |
| Configurable soft-start via SOFTST | 16 distinct startup profiles enable optimization for motor inertia, winding resistance, and load torque without firmware change. |
| Sensorless BEMF position detection | Eliminates Hall sensors or back-EMF resistive networks, reducing bill-of-materials and board space in compact fan modules. |
| Integrated lock detection & auto-restart | Monitors FG output period; disables outputs for 5 s after first lock, then full tOFF (5 s) delay before subsequent restart attempts. |
| Standby mode with 25 µA ICC | Enables ultra-low-power idle state when PWM remains low for >5 s; powers down VREF and gate drivers to minimize quiescent loss. |
Applications
| Server Cooling Fan | Industrial Enclosure Ventilation |
|---|---|
Use Scenario: High-density 1U/2U server chassis requiring silent operation during low-load periods and rapid thermal response under CPU/GPU load spikes. IC Role / Device Role / Timing Role: Three-phase sensorless fan driver providing sinusoidal commutation, FG-based closed-loop speed monitoring, and SOFTST-tuned startup to prevent stalling on high-inertia fans. Use Value: Achieves <35 dBA acoustic noise at 50% speed while maintaining ±3% RPM regulation across 10–85°C ambient, enabled by 25 kHz motor PWM and adaptive BEMF detection. | Use Scenario: Fan-cooled PLC cabinets and HMI enclosures deployed in factory-floor environments with wide temperature swings and dust exposure. IC Role / Device Role / Timing Role: Motor controller managing 12 V/24 V brushless fans with lock protection, thermal shutdown, and standby mode to reduce energy consumption during machine idle cycles. Use Value: Delivers 15-year field reliability via integrated short-circuit, overcurrent (850 mA typ.), and thermal (165°C) protections - validated per IEC 61000-4-2/4-4 immunity requirements. |
| Medical Imaging Chassis Cooling | Network Switch Thermal Management |
Use Scenario: MRI and CT scanner auxiliary cooling systems where electromagnetic compatibility and zero audible interference are mandatory near sensitive analog signal paths. IC Role / Device Role / Timing Role: Low-EMI fan driver using filtered PWM input, synchronous FG output, and exposed-pad thermal management to meet CISPR 32 Class B radiated emissions limits. Use Value: Sinusoidal drive eliminates 3rd/5th harmonic content in motor current, reducing conducted EMI by >12 dB compared to square-wave alternatives - critical for FDA 510(k) compliance. | Use Scenario: Multi-fan thermal subsystem in 48-port Ethernet switches with dynamic fan speed scaling based on ASIC junction temperature telemetry. IC Role / Device Role / Timing Role: Distributed fan controller receiving PWM commands from baseboard management controller (BMC), reporting RPM via FG to enable predictive fan failure analysis. Use Value: FG output provides deterministic 1:1 electrical revolution correlation, enabling accurate fan lifetime estimation (MTBF > 100,000 hrs) through RPM variance tracking over time. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar three-phase sensorless fan driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP6532GQ-Z | Higher 1.2 A peak output current; supports 12 V operation; no SOFTST pin - fixed startup profile. | Targets higher-power fans (>15 W); lacks analog startup tuning, requiring external MCU compensation for motor variation. | Select MP6532GQ-Z when driving larger axial fans with fixed motor parameters and need for extended voltage range. |
| DRV10983ZPWPR | Integrated 3.3 V LDO; SPI interface for real-time parameter adjustment; 18 V max VCC; no FG output - only tachometer pulse via GPIO. | Designed for automotive HVAC blower modules; requires firmware integration for configuration; lacks dedicated speed feedback pin. | Select DRV10983ZPWPR when system-level diagnostics, overvoltage tolerance, or programmable startup via host MCU are required. |
Compared with MP6532GQ-Z and DRV10983ZPWPR, the A5944GEETR-T offers unique analog-configurable startup (SOFTST), dedicated FG speed output, and optimized 25 kHz motor PWM for acoustic performance - making it ideal for cost-sensitive, high-volume server and industrial fan modules where simplicity and noise reduction are primary.
Availability
A5944GEETR-T is available at Aetrix Electronics and suitable for server cooling fans, industrial enclosure ventilation, medical imaging chassis cooling, and network switch thermal management requiring stable component supply and long-term production continuity.
Supply support for A5944GEETR-T 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
Allegro MicroSystems is a U.S.-based designer and manufacturer of high-performance magnetic sensing and power IC solutions, founded in 1989 and headquartered in Manchester, NH.
The A5944GEETR-T belongs to Allegro's fan driver product line, engineered specifically for quiet, efficient, and robust three-phase BLDC fan control in space-constrained, thermally demanding applications.
FAQ
What is the function of the SOFTST pin on the A5944GEETR-T?
The SOFTST pin on the A5944GEETR-T is an analog input that selects one of 16 predefined startup profiles by applying a voltage between 0 V and VREF (2.8 V). This adjusts open-loop duration, acceleration rate, and initial demand to match motor inertia and winding characteristics - eliminating trial-and-error tuning in production. A5944GEETR-T uses this feature to ensure reliable startup across diverse fan models without firmware changes.
Does the A5944GEETR-T require external Hall sensors for commutation?
No, the A5944GEETR-T operates in sensorless mode using back-EMF (BEMF) detection on the CTAP and phase terminals to determine rotor position. It opens a narrow timing window on phase A's modulation profile to sample BEMF without disrupting the sinusoidal current waveform. This eliminates the need for external Hall sensors, reducing system cost and board area while maintaining smooth, low-vibration operation in the A5944GEETR-T.
What is the maximum motor PWM frequency supported by the A5944GEETR-T?
The A5944GEETR-T supports a motor PWM frequency of 22.5–27.5 kHz (typ. 25 kHz), as specified for the A5944GEJTR-T variant. This ultrasonic switching frequency ensures fan operation remains inaudible to humans while maintaining high efficiency and low EMI. The A5944GEETR-T does not support the 45–55 kHz option found in the A5944GEJTR-1-T variant.
How does the A5944GEETR-T handle motor lock conditions?
The A5944GEETR-T detects motor lock by monitoring FG output period; if no transition occurs for tOFF = 4.5–5.5 s, it disables all outputs and enters a recovery sequence. After the first lock, it restarts after 1 s; subsequent locks enforce the full tOFF delay before restart. This dual-stage behavior prevents repeated failed startups while protecting the motor and A5944GEETR-T from thermal stress during persistent stall conditions.
Can the A5944GEETR-T operate from a 3.3 V supply?
No, the A5944GEETR-T is not rated for 3.3 V operation. Its recommended VCC range is 4.5–5.5 V, with absolute maximum ratings specifying 6 V and minimum functional voltage at 3 V only for transient conditions. Startup reliability and sinusoidal drive fidelity are guaranteed only within the 4.5–5.5 V range. Using 3.3 V may result in failed startup, unstable commutation, or undefined behavior in the A5944GEETR-T.
A5944GEETR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 10-UFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Motor Type - Stepper:
- Multiphase
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (3)
- Interface:
- Logic
- Technology:
- -
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- 500mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-DFN (3x3)
A5944GEETR-T FAQ
1.How can I place an order for A5944GEETR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5944GEETR-T 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 A5944GEETR-T reliable?
The price and inventory of A5944GEETR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5944GEETR-T is usually 5 days.
3.What payment methods are accepted for A5944GEETR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5944GEETR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5944GEETR-T?
A5944GEETR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5944GEETR-T 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 A5944GEETR-T?
For technical support, including A5944GEETR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5944GEETR-T requirements.
6.How does Aetrix verify that A5944GEETR-T is sourced from the original manufacturer or authorized distributors?
All A5944GEETR-T 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 A5944GEETR-T meets industry standards.
7.What is the process for return or replacement of A5944GEETR-T?
All A5944GEETR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5944GEETR-T, 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 A5944GEETR-T part is unused and in its original packaging.
Return procedure for A5944GEETR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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