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Allegro MicroSystems A5931KLPTR-T
- Part No.:
- A5931KLPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A5931KLPTR-T.pdf
- Description:
- AUTOMOTIVE 3-PHASE SENSORLESS SI
- Quantity:
- Payment:
- Shipping:
Inventory:4,274
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Product details
Overview
A5931KLPTR-T from Allegro MicroSystems is a three-phase sensorless fan driver IC designed for high-speed server fans, delivering sinusoidal motor control to minimize audible noise and mechanical vibration. It integrates closed-loop speed regulation, EEPROM-configurable speed curves, and 3 A motor phase current capability in a 16-lead TSSOP package with exposed thermal pad. The device operates across –40°C to +125°C and supports both PWM and analog (0.7–0.8 V threshold) speed demand inputs.
For engineers reviewing the A5931KLPTR-T datasheet, A5931KLPTR-T pinout, A5931KLPTR-T application, or A5931KLPTR-T equivalent, this page delivers verified technical context-including K-version thermal rating, SPD analog input specification, RDS(ON) at 125°C, and I²C address 0x55-essential for server cooling system design, thermal management validation, and drop-in replacement evaluation.
Technical Context
The A5931KLPTR-T implements sensorless sinusoidal commutation using back-EMF detection without Hall sensors, enabling smooth rotation and low-vibration operation in brushless DC fans. Its integrated charge pump drives low-RDS(ON) MOSFETs (225–265 mΩ at 125°C), and closed-loop control uses a 9-bit SPD input interpreted via configurable EEPROM speed curve parameters including DCON = 10% and SPDADC resolution of 4.82 mV/LSB.
It features dual-mode speed input: PWM (6–100 kHz) or analog voltage (0.7–0.8 V on/off thresholds), with I²C interface (7-bit address 0x55) shared between FG (SDA) and SPD (SCL) pins. Protection includes rotor lock detection (RD output), overcurrent shutdown (6.5 A), thermal shutdown (165°C), and undervoltage lockout (4.3 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 5–16 V DC - supports standard 12 V server fan rails with 20 V transient tolerance |
| Operating Temperature | –40°C to +125°C - qualified per AEC-Q100 Grade K for extended thermal environments |
| Motor Current | 3000 mA peak phase current - enables direct drive of high-airflow server fans without external FETs |
| RDS(ON) @ 125°C | 225–265 mΩ - gold-bondwire LP package ensures stable conduction under sustained thermal stress |
| SPD Input Threshold | VSPDON = 300 mV, VSPDOFF = 258 mV - precise analog speed enable/disable for low-noise standby transitions |
| I²C Address | 0x55 - fixed slave address enables deterministic firmware integration in multi-device thermal systems |
| FG Output | Open-drain, two pulses per mechanical revolution - provides RPM feedback compatible with standard fan monitoring circuits |
Pinout & Package
The A5931KLPTR-T is housed in a 16-lead TSSOP package with exposed thermal pad (LP suffix), optimized for thermal dissipation on 2-layer PCBs (RθJA = 35°C/W). Lead finish is 100% matte tin; RoHS and lead-free compliant.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | FG | Open-drain tachometer output (2 pulses/rev) and I²C SDA line - enables dual-function pin sharing with serial programming |
| 2 | SPD | Speed demand input - accepts PWM (6–100 kHz) or analog voltage (0.7–0.8 V thresholds); also serves as I²C SCL |
| 3 | RD | Open-drain rotor lock fault indicator - logic-high asserts on locked-rotor condition per EEPROM-configured RDHIGH/RDLOW |
| 4 | VCP | Charge pump capacitor connection - supplies gate drive voltage for high-side MOSFETs in 3-phase bridge |
| 5–6 | LSS | Low-side source return - dual pins reduce IR drop and improve current sensing accuracy for OCP |
| 7–8 | OUTA / OUTB | Motor phase terminals - drive Wye- or Delta-connected BLDC fan windings with sinusoidal modulation |
| 9–11 | VBB / OUTC / VBB | Power input (dual VBB pins) and third motor phase - redundant VBB routing lowers supply impedance |
| 12–13 | OUTC / LSS | Third motor phase and second low-side return - completes 3-phase output stage with symmetric layout |
| 14–16 | VREF / CTAP / GND | 2.85 V reference output, motor common tap (for Wye motors, 2 kΩ series resistor required), and ground reference |
Key Features
| Feature | Design Value |
|---|---|
| Sinusoidal modulation | Reduces torque ripple and acoustic noise by replacing trapezoidal switching with smooth current waveforms |
| EEPROM-configurable speed curve | Enables application-specific fan profiles (e.g., linear, dual-slope, clamp-enabled) without MCU firmware changes |
| Integrated charge pump | Eliminates need for external high-voltage bias supply - enables full 12 V gate drive for N-channel high-side FETs |
| SPD analog input mode | Supports 0.7–0.8 V on/off thresholds and 4.82 mV/LSB ADC resolution - simplifies analog thermal control loop integration |
| RD rotor lock detection | Configurable timing (RDBLANK, RDDLY) and RPM thresholds (RDHIGH/RDLOW) allow precise fault response tuning |
| Thermal shutdown with hysteresis | Triggers at 165°C with 20°C hysteresis - prevents thermal cycling and ensures safe recovery before restart |
Applications
| Data Center Server Cooling | Enterprise Storage Enclosure Fans |
|---|---|
|
Use Scenario: High-density 1U/2U servers requiring silent, vibration-free airflow under variable thermal loads. IC Role / Device Role / Timing Role: Primary fan controller executing sensorless sinusoidal commutation and closed-loop RPM regulation via SPD input. Use Value: Eliminates Hall sensors and MCU, reducing BOM cost and PCB area while maintaining <±5% speed accuracy across –40°C to +125°C. |
Use Scenario: Redundant cooling in JBOD/NAS enclosures where fan failure must trigger immediate alert and failover. IC Role / Device Role / Timing Role: Fault-aware motor driver providing RD output for lock detection and FG for real-time RPM telemetry. Use Value: RD signal configured with 100 ms RDBLANK and 16 rpm resolution enables reliable stall detection before thermal throttling occurs. |
| Industrial Rack-Mount Switches | High-Performance GPU Compute Servers |
|
Use Scenario: Fan control in fanless-designed switches with external blower modules subject to dust accumulation and bearing wear. IC Role / Device Role / Timing Role: Analog-input-capable driver accepting thermistor-derived voltage for adaptive speed scaling. Use Value: SPD analog mode (0.7 V on-threshold) allows direct connection to op-amp-based thermal amplifiers without ADC or level-shifting. |
Use Scenario: Multi-fan cooling for dual-GPU servers where synchronized low-noise operation prevents acoustic interference. IC Role / Device Role / Timing Role: Sinusoidal drive IC minimizing electromagnetic interference (EMI) and mechanical resonance in tightly packed chassis. Use Value: 24.4 kHz PWM frequency and soft-start reduce inrush current and avoid excitation of structural resonances above 20 kHz. |
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 |
|---|---|---|---|
| A5931GLPTR-T | Same pinout and feature set, but rated for –40°C to +105°C (G version); RDS(ON) lower (210–250 mΩ @ 25°C) due to copper bond wires | Targeted at commercial-grade servers without extended temperature requirements | Select when operating ambient stays below 105°C and lower conduction loss at room temperature is prioritized |
| MP6532DJ-LF-Z | 3-phase driver with Hall sensor support only; no sensorless mode; no EEPROM; 2.5 A rating; QFN-24 package | Requires external position sensors and MCU for closed-loop control; lacks analog SPD input and RD fault signaling | Choose only if Hall-based commutation is mandated and system already includes position sensing infrastructure |
Compared with A5931GLPTR-T, the A5931KLPTR-T trades marginally higher RDS(ON) at 125°C for guaranteed operation up to +125°C junction temperature, while MP6532DJ-LF-Z lacks sensorless capability and embedded speed control-making it unsuitable as a functional substitute without redesigning the entire fan control architecture.
Availability
A5931KLPTR-T is available at Aetrix Electronics and suitable for data center thermal management, enterprise storage enclosure cooling, and industrial network switch fan control requiring stable component supply across extended temperature ranges.
Supply support for A5931KLPTR-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 semiconductor company specializing in high-performance power ICs, magnetic sensors, and motor driver solutions for automotive, industrial, and computing markets.
The A5931 product line targets high-reliability server and storage cooling applications, integrating sensorless sinusoidal drive, EEPROM programmability, and robust protection to replace discrete MCU-based fan controllers.
FAQ
What is the operating temperature range for the A5931KLPTR-T?
The A5931KLPTR-T is AEC-Q100 Grade K qualified and operates from –40°C to +125°C ambient temperature. This extended range is enabled by gold bond wire construction and thermal design optimized for high-power server fan applications where junction temperatures may exceed 105°C. The K-version rating is explicitly confirmed in the Selection Guide table for A5931KLPTR-T.
Does the A5931KLPTR-T support analog speed control, and what are its voltage thresholds?
Yes, the A5931KLPTR-T supports analog speed control via the SPD pin. Its analog mode is exclusive to the KLP and KES variants. The on-threshold (VSPDON) is 300 mV, off-threshold (VSPDOFF) is 258 mV, and the ADC resolution is 4.82 mV/LSB - all specified in the Electrical Characteristics table for A5931KLPTR-T only. These values enable precise low-voltage thermal loop integration.
What is the I²C slave address of the A5931KLPTR-T, and how are the SDA/SCL pins assigned?
The A5931KLPTR-T uses a fixed 7-bit I²C slave address of 0x55. The SPD pin functions as the SCL (clock) input, and the FG pin serves as the SDA (data) line - a shared-pin configuration documented in the Serial Port section. This dual-role assignment allows in-system programming without additional pins, though SPD input is disabled during active I²C communication.
How does the RD output function on the A5931KLPTR-T, and can it be disabled?
The RD output on the A5931KLPTR-T is an open-drain rotor lock fault indicator that asserts logic-high when motor speed falls below EEPROM-configured RDLOW or fails to reach RDHIGH after RDBLANK timeout. RD can be fully disabled by setting RDHIGH = 0 in EEPROM, causing the pin to go high only after open-loop startup completion - a behavior confirmed in the RD Function section and Table 2.
What is the maximum motor phase current supported by the A5931KLPTR-T, and how is it achieved?
The A5931KLPTR-T supports up to 3000 mA motor phase current in sinusoidal running mode, as specified in the Recommended Operational Range table. This is achieved through integrated low-RDS(ON) power MOSFETs (225–265 mΩ at 125°C), a charge pump for full gate drive, and thermal design leveraging the exposed pad in the 16-lead TSSOP package - enabling direct drive of high-airflow server fans without external drivers.
A5931KLPTR-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 ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-eTSSOP-EP
A5931KLPTR-T FAQ
1.How can I place an order for A5931KLPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5931KLPTR-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 A5931KLPTR-T reliable?
The price and inventory of A5931KLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5931KLPTR-T is usually 5 days.
3.What payment methods are accepted for A5931KLPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5931KLPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5931KLPTR-T?
A5931KLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5931KLPTR-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 A5931KLPTR-T?
For technical support, including A5931KLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5931KLPTR-T requirements.
6.How does Aetrix verify that A5931KLPTR-T is sourced from the original manufacturer or authorized distributors?
All A5931KLPTR-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 A5931KLPTR-T meets industry standards.
7.What is the process for return or replacement of A5931KLPTR-T?
All A5931KLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5931KLPTR-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 A5931KLPTR-T part is unused and in its original packaging.
Return procedure for A5931KLPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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