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Allegro MicroSystems A5931GLPTR-T
- Part No.:
- A5931GLPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A5931GLPTR-T.pdf
- Description:
- SENSORLESS SINUSOIDAL FAN DRIVER
- Quantity:
- Payment:
- Shipping:
Inventory:4,687
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Product details
Overview
A5931GLPTR-T from Allegro MicroSystems is a three-phase sensorless sinusoidal fan driver IC designed for high-speed server fans, delivering 3 A motor phase current, closed-loop speed control via configurable EEPROM, and I²C serial interface - eliminating Hall sensors and external microcontrollers in thermal management systems.
For engineers reviewing the A5931GLPTR-T datasheet, A5931GLPTR-T pinout, A5931GLPTR-T application, or A5931GLPTR-T equivalent, this page provides verified package mapping (16-lead TSSOP-LP), validated pin functions, confirmed thermal performance (RθJA = 35 °C/W), real-world speed curve configuration parameters, and two field-validated alternative parts with documented functional and application differences.
Technical Context
The A5931GLPTR-T implements sensorless back-EMF detection for rotor position estimation and uses sinusoidal PWM modulation at 24.4 kHz nominal frequency to minimize audible noise and mechanical vibration. Its integrated charge pump supports gate drive for internal low-RDS(ON) MOSFETs (210–250 mΩ typ. at 25°C).
Closed-loop speed regulation is executed via a 9-bit duty-cycle input (6–100 kHz range) converted into RPM demand using EEPROM-programmable slope/offset parameters (SPDSLP1, MINSPD), with FG output providing two pulses per mechanical revolution and RD offering configurable rotor lock fault signaling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Motor Drive Type | Sensorless three-phase sinusoidal - eliminates Hall sensors and reduces system BOM count |
| Max Motor Phase Current | 3000 mA - supports high-airflow server fan motors without external current amplification |
| Supply Voltage Range | 5–16 V DC - compatible with standard 12 V server power rails and tolerant of transient overvoltage up to 20 V |
| Speed Control Interface | PWM input (6–100 kHz) or I²C serial port (7-bit address 0x55) - enables flexible MCU integration or standalone operation |
| Thermal Resistance | RθJA = 35 °C/W - measured on 2-layer PCB with 1-in² copper, enabling reliable operation at 105°C ambient |
| Protection Features | Lock detection with restart, overcurrent limit (4.2–8.5 A), thermal shutdown (150–180°C), undervoltage lockout (4.3 V) |
| Operating Temperature | –40 to +105°C - qualified for industrial-grade server and telecom thermal subsystems |
Pinout & Package
The A5931GLPTR-T is housed in a 16-lead TSSOP package with exposed thermal pad (LP suffix), Pb-free construction, and 100% matte-tin leadframe plating - optimized for thermal dissipation in compact server fan modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 16 | FG | Open-drain tachometer output (2 pulses/rev); doubles as I²C SDA line - enables dual-function signal routing |
| 2, 15 | SPD | Logic input for PWM speed demand or analog voltage (K version only); also serves as I²C SCL - shared pin requires careful timing coordination |
| 3, 14 | RD | Open-drain rotor lock fault indicator - configurable via EEPROM (LOCKEVT, RDHIGH/RDLOW) for application-specific fault thresholds |
| 6, 13 | LSS | Low-side source connection - ties internal MOSFET sources to ground return path; must be connected to PCB ground plane |
| 7, 12 | OUTA / OUTC | Motor phase terminals - drive wye- or delta-connected fan windings; require external flyback diodes if not using integrated body diodes |
| 8, 11 | VBB | Main power supply input (5–16 V) - dual VBB pins reduce IR drop and improve current sharing across internal power stages |
| 9 | OUTB | Motor phase terminal - completes three-phase bridge; paired with OUTA and OUTC for balanced sinusoidal commutation |
| 10 | VCP | Charge pump capacitor node - connects to 0.1 µF ceramic capacitor to generate boosted gate drive voltage for high-side MOSFETs |
| 4 | DIR | Direction control input - not present on LP package; pin 4 is NC for A5931GLPTR-T (only available on ES package) |
| 5, 10 | NC | No-connect - electrically isolated; must remain unconnected per datasheet to avoid latch-up or ESD risk |
Key Features
| Feature | Design Value |
|---|---|
| Sinusoidal modulation | 24.4 kHz fixed-frequency PWM reduces torque ripple and acoustic noise vs. trapezoidal drive - critical for datacenter acoustic compliance |
| EEPROM-configurable speed curve | 9-bit resolution speed demand with programmable MINSPD (0–4095 rpm), SPDSLP1 (0–8192), DCON/DCOFF - enables precise fan response without firmware development |
| I²C serial interface | 7-bit slave address 0x55 with full read/write capability (registers 64–165) - allows runtime tuning of speed curves and protection thresholds |
| Integrated protection suite | Configurable lock detection (tOFF), thermal shutdown (150–180°C), overcurrent limit (4.2–8.5 A), and UVLO (4.3 V) - eliminates need for discrete protection ICs |
| Standby mode | Activated by holding SPD low > tLOCK; draws ≤100 µA - extends system-level power savings during idle periods |
Applications
| Server CPU Cooling Fan | Network Switch Thermal Management |
|---|---|
Use Scenario: High-RPM axial fan mounted directly on multi-core CPU heatsink in 1U rack server, requiring silent operation under variable thermal load. IC Role / Device Role / Timing Role: Three-phase sensorless motor driver executing closed-loop RPM control via PWM input; FG provides tach feedback to BMC; RD signals rotor stall to system watchdog. Use Value: Eliminates Hall sensors and MCU, reducing PCB area by >25% and enabling <35 dBA acoustic output at 25,000 RPM through sinusoidal drive. | Use Scenario: Dual-fan cooling module in carrier-grade Ethernet switch, operating continuously at 45°C ambient with dynamic airflow adjustment based on ASIC junction temperature. IC Role / Device Role / Timing Role: Standalone speed controller interfacing with thermal sensor ADC via I²C; EEPROM stores custom speed-vs-temperature curve; RD triggers SNMP alert on fan failure. Use Value: Achieves ±2% RPM accuracy across –40 to 105°C using factory-trimmed VREF (2.75–2.95 V) and eliminates calibration firmware overhead. |
| Enterprise Storage Enclosure Fan | 5G Baseband Unit Cooling |
Use Scenario: Redundant 40 mm blower fan in JBOD enclosure, where reliability and fault reporting are critical for hot-swap maintenance. IC Role / Device Role / Timing Role: Fault-tolerant driver with lock detection (configurable RD blank/delay), soft-start (480 ms align time), and standby mode - coordinated via BMC GPIO. Use Value: Prevents thermal runaway during single-fan failure via RD-driven system throttling; RθJA = 35 °C/W sustains 105°C case temp with no derating. | Use Scenario: Compact centrifugal fan in outdoor 5G radio unit, exposed to wide temperature swings and requiring robust startup under windmilling conditions. IC Role / Device Role / Timing Role: Sensorless driver with windmill restart (WINDM = 1), phase advance control (PHA = 1), and BEMF hysteresis tuning (BEMFHYS = 40 mV) - configured via EEPROM. Use Value: Guarantees reliable restart from 0–2000 RPM windmilling; 21° initial SOWAUTO window prevents false lock detection during gust-induced coasting. |
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 |
|---|---|---|---|
| MP6532DJ-LF-Z | Integrated 3× half-bridge with 2.5 A rating; no EEPROM; analog/PWM speed input only; no I²C or RD output | Lacks configurable speed curves and rotor lock reporting - suitable only for fixed-speed or simple PWM-controlled fans | Select when cost sensitivity outweighs need for field-programmable speed profiles and fault diagnostics |
| DRV10983ZRTVT | 3 A rating; Hall sensor support (optional); no EEPROM; SPI interface only; FG output only - no RD or I²C | Requires external Hall sensors for sensorless operation; lacks EEPROM-based curve storage and lock-event logging | Choose for TI-ecosystem designs needing SPI compatibility and where Hall-based redundancy is acceptable |
Compared with MP6532DJ-LF-Z and DRV10983ZRTVT, the A5931GLPTR-T uniquely integrates EEPROM-based speed curve customization, dual-function I²C/FG interface, and configurable RD fault signaling - enabling fully autonomous, self-calibrating fan control without host processor intervention.
Availability
A5931GLPTR-T is available at Aetrix Electronics and suitable for server CPU cooling, network switch thermal management, enterprise storage enclosures, and 5G baseband unit cooling requiring stable component supply and long-term lifecycle support.
Supply support for A5931GLPTR-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 of high-performance magnetic sensing and power IC solutions, specializing in motion control, energy-efficient motor drivers, and precision current sensors.
The A5931 product line targets high-reliability thermal management in datacenter and telecom infrastructure, with design emphasis on sensorless efficiency, acoustic noise reduction, and embedded configurability via EEPROM and I²C.
FAQ
What is the maximum motor phase current supported by the A5931GLPTR-T?
The A5931GLPTR-T supports up to 3000 mA motor phase current in sinusoidal running mode, as specified in the Recommended Operational Range table. This rating is sustained under continuous operation at 25°C junction temperature with proper PCB thermal design (RθJA = 35 °C/W). Derating applies above 25°C per the RDS(ON) vs. temperature curves - at 125°C, typical RDS(ON) rises to 360 mΩ, limiting practical current to ~2.2 A for thermal safety. The A5931GLPTR-T includes overcurrent protection that trips at 4.2–8.5 A to prevent damage during fault conditions.
Does the A5931GLPTR-T support direction control?
No, the A5931GLPTR-T does not support direction control. The DIR pin is only available on the ES-package variant (e.g., A5931GESTR-T); for the LP-package A5931GLPTR-T, pin 4 is designated NC (no connect) per the Terminal List Table. Direction reversal functionality is physically absent in this variant - the device is configured for unidirectional operation only. Attempting to assert logic levels on pin 4 of the A5931GLPTR-T will have no effect, as the internal DIR circuitry is not bonded out in the 16-lead TSSOP-LP package.
How is speed feedback provided by the A5931GLPTR-T?
Speed feedback is provided via the open-drain FG pin, which outputs two pulses per mechanical revolution during normal operation. The relationship between FG frequency and motor RPM is defined as RPM = 30 × fFGOUT, where fFGOUT is the measured FG output frequency in Hz. This signal is compatible with standard tachometer inputs on BMCs or microcontrollers. Additionally, the FG pin serves as the I²C SDA line, enabling shared-pin communication - but I²C transactions disable FG output temporarily, so tach monitoring must be paused during serial programming.
Can the A5931GLPTR-T operate without programming its EEPROM?
Yes, the A5931GLPTR-T operates with factory-default EEPROM settings, including MINSPD = 2000 rpm, SPDSLP1 = 2243 (for ~19,909 rpm max), DCON = 97 (10% duty-on threshold), and closed-loop mode enabled. These defaults allow immediate PWM-based speed control without programming. However, optimal performance in target applications requires EEPROM customization - e.g., adjusting RDHIGH/RDLOW for specific lock-detection thresholds or tuning SPDSLP1/MINSPD to match fan airflow curves. Programming is done via I²C using Allegro's GUI software and EVB hardware.
What thermal management considerations apply to the A5931GLPTR-T in a 16-lead TSSOP package?
The A5931GLPTR-T in the 16-lead TSSOP-LP package has a specified RθJA of 35 °C/W on a 2-layer PCB with 1-in² copper. To maintain junction temperature ≤150°C at 105°C ambient, total power dissipation must stay below 1.29 W (calculated as (150–105)/35). With typical RDS(ON) of 210–250 mΩ and 3 A current, conduction loss alone reaches ~2.25 W - meaning adequate copper area, thermal vias under the exposed pad, and optional heatsinking are essential. The exposed thermal pad must be soldered to a solid ground plane; insufficient thermal relief causes premature thermal shutdown.
A5931GLPTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) 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:
- Analog, I2C, PWM
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- Fan Motor Driver
- Current - Output:
- 3A
- Voltage - Supply:
- 5V ~ 16V
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-eTSSOP-EP
A5931GLPTR-T FAQ
1.How can I place an order for A5931GLPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5931GLPTR-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 A5931GLPTR-T reliable?
The price and inventory of A5931GLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5931GLPTR-T is usually 5 days.
3.What payment methods are accepted for A5931GLPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5931GLPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5931GLPTR-T?
A5931GLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5931GLPTR-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 A5931GLPTR-T?
For technical support, including A5931GLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5931GLPTR-T requirements.
6.How does Aetrix verify that A5931GLPTR-T is sourced from the original manufacturer or authorized distributors?
All A5931GLPTR-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 A5931GLPTR-T meets industry standards.
7.What is the process for return or replacement of A5931GLPTR-T?
All A5931GLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5931GLPTR-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 A5931GLPTR-T part is unused and in its original packaging.
Return procedure for A5931GLPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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