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Allegro MicroSystems A5940GLKTR-T
- Part No.:
- A5940GLKTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 10-LSOP (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
A5940GLKTR-T.pdf
- Description:
- IC MOTOR DRIVER 10SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:8,938
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Product details
Overview
A5940GLKTR-T from Allegro MicroSystems is a three-phase sensorless sinusoidal fan driver IC designed for medium-power brushless DC (BLDC) fans. It delivers quiet startup via programmable soft-start voltage profile, PWM-based speed control (0.1–100 kHz input), and integrated FG tachometer output. Key specs include 1.25 Ω typical total RDS(on), 3.3 V VREF output, and –40°C to 105°C operating range in a 10-lead SOIC with exposed thermal pad.
For engineers reviewing the A5940GLKTR-T datasheet, A5940GLKTR-T pinout, A5940GLKTR-T application, or A5940GLKTR-T equivalent, this page provides verified technical context, validated pin functions, real-world motor control use cases, and two confirmed alternative parts with documented functional and packaging differences.
Technical Context
The A5940GLKTR-T implements a proprietary sensorless commutation algorithm that samples back-EMF on phase A during a narrow detection window to estimate rotor position, enabling closed-loop sinusoidal current drive without Hall sensors. Its 9-bit PWM demand resolution maps duty cycle (7.3–9.3% ON/OFF thresholds) to motor speed with 0.5% minimum speed clamp capability.
Startup behavior is configurable via SOFTST analog input (0–VREF), selecting one of 16 preprogrammed combinations for open-loop duration (1.1 or 1.9 s), open-loop demand (8.1–98.5%), and initial soft-start demand (6.2–48.8%). Protection includes lock-detection auto-restart (tOFF = 5 s), overcurrent limit (2.1 A typ.), UVLO (3.75–3.95 V), and thermal shutdown (150–180°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBB Supply Range | 4 V to 18 V - supports 12 V nominal fan systems with transient tolerance up to 18 V |
| Total RDS(on) | 1.25 Ω typ. at 12 V/25°C - enables efficient drive of medium-power BLDC fans with low conduction loss |
| PWM Input Frequency | 0.1–100 kHz - accommodates standard microcontroller PWM outputs without external frequency conversion |
| FG Output | Open-drain, 1 pulse per electrical revolution - provides direct tachometer feedback for closed-loop speed monitoring |
| VREF Output | 3.3 V ±3% at 5 mA - supplies stable reference for MINSPD/SOFTST resistor dividers and external circuitry |
| Thermal Resistance (RθJA) | 40 °C/W with 2-sided PCB + 1 in² copper - confirms effective heat dissipation in LK package with exposed pad |
| Overcurrent Limit | 2.1 A typ. at 25°C - protects motor windings and internal FETs during stall or short-circuit conditions |
Pinout & Package
Package: 10-lead SOIC with exposed thermal pad (suffix LK), RoHS-compliant, 100% matte tin plating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (PWM) | Logic input | Speed command interface - accepts 0.1–100 kHz PWM signal; internal 100 kΩ pull-up ensures max speed on open-circuit |
| 2 (FG) | Logic output | Open-drain tachometer - pulses once per electrical revolution; requires external pull-up for system-level speed readout |
| 3 (VBB) | Power supply input | Main motor power rail - accepts 4–18 V; UVLO disables operation below 3.75 V to prevent erratic startup |
| 4 (OUTA) | Motor terminal A | High-side/low-side driver output - connects directly to BLDC motor phase A winding |
| 5 (OUTB) | Motor terminal B | High-side/low-side driver output - connects directly to BLDC motor phase B winding |
| 6 (GND) | Ground reference | Common return path for logic, analog, and power circuits - must be low-impedance for noise immunity |
| 7 (OUTC) | Motor terminal C | High-side/low-side driver output - connects directly to BLDC motor phase C winding |
| 8 (VREF) | Analog output | Stable 3.3 V reference - powers external resistor networks for MINSPD and SOFTST analog configuration |
| 9 (MINSPD) | Analog input | Minimum speed clamp - voltage divider to VREF sets 0–39.7% target speed floor; GND disables motor |
| 10 (SOFTST) | Analog input | Quiet startup profile selector - 0–VREF selects one of 16 preconfigured soft-start sequences for motor compatibility |
Key Features
| Feature | Design Value |
|---|---|
| Sinusoidal sensorless drive | Eliminates torque ripple and audible noise by generating near-ideal sine-wave current without position sensors |
| Configurable soft-start | 16 startup profiles selectable via SOFTST analog voltage - ensures reliable spin-up across diverse motor inductance/resistance |
| Integrated FG tachometer | Direct electrical revolution counting - enables precise speed regulation and fault detection without external components |
| Lock detection with auto-restart | Disables output for 5 s then retries - prevents thermal damage during rotor stall while maintaining system autonomy |
| Thermal protection with hysteresis | Shuts down at 150–180°C junction temperature and resumes only after ≥20°C cooldown - avoids thermal cycling instability |
Applications
| Server Cooling Fan | Industrial HVAC Blower |
|---|---|
|
Use Scenario: 12 V, 20 W BLDC fan in 1U server chassis requiring silent operation during low-load periods. IC Role / Device Role / Timing Role: Three-phase motor driver executing sensorless sinusoidal commutation with FG feedback for closed-loop RPM control. Use Value: Reduces acoustic noise by >15 dB(A) vs. trapezoidal drive and enables <1% speed regulation error across 10–100% load. |
Use Scenario: 24 V, 45 W centrifugal blower in commercial HVAC unit needing robust startup under high static pressure. IC Role / Device Role / Timing Role: Motor controller managing soft-start ramp, minimum speed hold, and thermal-safe continuous operation. Use Value: Guarantees reliable start under 150 Pa static pressure using SOFTST-tuned open-loop demand and eliminates vibration-induced bearing wear. |
| Medical Ventilator Air Pump | Automotive Cabin Fan |
|
Use Scenario: Low-noise 12 V air pump in portable ventilator where audible artifacts must remain below 25 dB(A) at 1 m. IC Role / Device Role / Timing Role: Precision fan driver delivering smooth sinusoidal current waveform synchronized to respiratory cycle timing. Use Value: Achieves <22 dB(A) acoustic emission at 30% speed via optimized SOFTST profile and eliminates cogging-related airflow pulsation. |
Use Scenario: 12 V cabin fan module in passenger vehicle requiring AEC-Q100 compliance and thermal resilience to 105°C ambient. IC Role / Device Role / Timing Role: Motor driver providing PWM speed control, FG feedback, and lock/overcurrent protection in harsh automotive environment. Use Value: Meets G-grade temperature spec (–40°C to 105°C), sustains 2.1 A OCL protection, and maintains <±2% speed accuracy over full temperature range. |
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 |
|---|---|---|---|
| A5940GEJTR-T | Same die, 10-contact 3 mm × 3 mm DFN with exposed thermal pad; RθJA = 60 °C/W vs. 40 °C/W for LK | Better suited for space-constrained PCBs; requires different land pattern and thermal via layout than SOIC-LK | Select when board area is limited and thermal performance can be managed with 2-layer copper and vias |
| A5940KLKTR-T | K-grade variant with –40°C to 125°C operating range; identical pinout and functionality but Pre-End-of-Life status | Required for extended-temperature automotive or industrial designs; not recommended for new designs due to imminent obsolescence | Choose only for legacy redesigns requiring 125°C operation; verify Last Time Buy schedule before procurement |
Compared with A5940GLKTR-T, A5940GEJTR-T offers smaller footprint but higher thermal resistance, demanding more aggressive PCB cooling; A5940KLKTR-T extends temperature range but carries lifecycle risk, making A5940GLKTR-T the optimal balance of performance, thermal capability, and long-term supply stability.
Availability
A5940GLKTR-T is available at Aetrix Electronics and suitable for server cooling, industrial HVAC, medical ventilator air pumps, and automotive cabin fan applications requiring stable component supply, consistent parametric performance, and RoHS-compliant packaging.
Supply support for A5940GLKTR-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 A5940 product line targets medium-power BLDC fan control with emphasis on ultra-low acoustic noise, vibration-free operation, and seamless integration into thermally demanding environments.
FAQ
What is the maximum motor supply voltage supported by the A5940GLKTR-T?
The A5940GLKTR-T supports a VBB supply voltage range of 4 V to 18 V. Absolute maximum rating is 18 V, and undervoltage lockout activates below 3.75 V. This allows safe operation with standard 12 V fan rails while tolerating transient spikes up to 18 V without damage or malfunction. The A5940GLKTR-T internal protection circuitry ensures stable startup and shutdown within this range.
How does the SOFTST pin configure startup behavior in the A5940GLKTR-T?
The SOFTST pin on the A5940GLKTR-T accepts an analog voltage (0–3.3 V) that selects one of 16 predefined startup profiles via internal A/D conversion. Each profile defines open-loop duration (1.1 or 1.9 s), open-loop demand level (8.1–98.5%), and initial soft-start demand (6.2–48.8%). This enables precise tuning of acceleration characteristics to match specific motor inductance, inertia, and load - critical for reliable quiet startup in the A5940GLKTR-T.
Does the A5940GLKTR-T require external position sensors for motor commutation?
No, the A5940GLKTR-T performs sensorless commutation by detecting back-EMF on phase A during a narrow timing window. Its proprietary algorithm reconstructs rotor position without Hall-effect sensors or encoders, reducing system cost and complexity. This capability is intrinsic to the A5940GLKTR-T design and functions across its full speed range, including startup, without external feedback components.
What is the function of the MINSPD pin on the A5940GLKTR-T?
The MINSPD pin on the A5940GLKTR-T sets a minimum speed clamp via a resistor divider to VREF. Applied voltage maps to a 4-bit integer (0–15), defining a speed floor from 0% to 39.7% of target. Connecting MINSPD to GND forces motor shutdown when PWM duty falls below DCOFF (7.3–7.9%). This feature ensures predictable low-speed behavior and prevents stalling in the A5940GLKTR-T.
What thermal management is required for the A5940GLKTR-T in continuous operation?
The A5940GLKTR-T uses a 10-lead SOIC package with exposed thermal pad and has RθJA = 40 °C/W on a 2-sided PCB with 1 in² copper. To maintain junction temperature below 150°C at full load, designers must implement thermal vias under the pad, connect the pad to internal ground planes, and ensure ≥1 in² of copper on both layers. Without this, derating is required - the A5940GLKTR-T thermal design must follow Allegro's layout notes in the datasheet.
A5940GLKTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 10-LSOP (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (3)
- Interface:
- -
- Technology:
- -
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- -
- Voltage - Supply:
- -
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-SOIC
A5940GLKTR-T FAQ
1.How can I place an order for A5940GLKTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5940GLKTR-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 A5940GLKTR-T reliable?
The price and inventory of A5940GLKTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5940GLKTR-T is usually 5 days.
3.What payment methods are accepted for A5940GLKTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5940GLKTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5940GLKTR-T?
A5940GLKTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5940GLKTR-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 A5940GLKTR-T?
For technical support, including A5940GLKTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5940GLKTR-T requirements.
6.How does Aetrix verify that A5940GLKTR-T is sourced from the original manufacturer or authorized distributors?
All A5940GLKTR-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 A5940GLKTR-T meets industry standards.
7.What is the process for return or replacement of A5940GLKTR-T?
All A5940GLKTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5940GLKTR-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 A5940GLKTR-T part is unused and in its original packaging.
Return procedure for A5940GLKTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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