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Allegro MicroSystems A5931KESTR-1-J
- Part No.:
- A5931KESTR-1-J
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
A5931KESTR-1-J.pdf
- Description:
- AUTOMOTIVE 3-PHASE SENSORLESS SI
- Quantity:
- Payment:
- Shipping:
Inventory:2,626
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Product details
Overview
A5931KESTR-1-J from Allegro MicroSystems is a three-phase sensorless sinusoidal fan driver IC designed for high-speed server fans, delivering closed-loop speed control, EEPROM-configurable speed curves, and integrated 3 A MOSFET drivers with RDS(ON) ≤ 265 mΩ (TJ = 25°C). It eliminates Hall sensors, supports I²C programming, and operates across –40°C to +125°C.
For engineers reviewing the A5931KESTR-1-J datasheet, A5931KESTR-1-J pinout, A5931KESTR-1-J application, or A5931KESTR-1-J equivalent, this page provides verified functional context, thermal performance data (RθJA = 35°C/W), real-world protection thresholds (OCP = 6.5 A, TJSD = 165°C), and validated alternative options for server cooling systems requiring AEC-Q100 qualified motor control.
Technical Context
The A5931KESTR-1-J implements sensorless back-EMF detection for commutation without position sensors, using sinusoidal modulation at 24.4 kHz nominal PWM frequency to minimize audible noise and mechanical vibration. Its closed-loop speed control system interprets 9-bit PWM duty input (6–100 kHz) or analog SPD voltage (K-version only) and maps it to RPM via EEPROM-defined linear or dual-slope speed curves.
It integrates charge-pump gate drivers, FG tachometer output (2 pulses/rev), RD rotor-lock fault flag, and configurable protections including overcurrent (6.5 A), thermal shutdown (165°C), undervoltage lockout (4.3 V), and lock-detection timing with programmable blanking (0.1–25.4 s) and delay (0–15 s).
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 |
| Motor Current | 3000 mA continuous - enables direct drive of high-RPM 3-phase BLDC fans up to ~25,000 RPM |
| RDS(ON) | 225–265 mΩ (TJ = 25°C) - low conduction loss for efficient thermal management in compact 16-lead TSSOP |
| PWM Frequency | 23.4–25.4 kHz - ultrasonic switching avoids audible noise while enabling precise speed resolution (0.2% duty step) |
| Operating Temp | –40°C to +125°C - AEC-Q100 Grade K qualification ensures reliability in thermally demanding server chassis environments |
| I²C Address | 0x55 - enables serial configuration and real-time speed control without MCU intervention |
| Thermal Resistance | RθJA = 35°C/W - measured on 2-layer PCB with exposed pad; defines maximum power dissipation before thermal shutdown |
Pinout & Package
Package: 16-lead TSSOP with exposed thermal pad (LP suffix), Pb-free, 100% matte-tin leadframe plating, 4.4 mm × 5.0 mm footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (PAD) | Exposed thermal pad | Primary heat path to PCB; must be soldered to copper pour for RθJA = 35°C/W performance |
| 1 | FG | Open-drain tachometer output (2 pulses/rev) and I²C SDA line - shared function requires careful timing coordination |
| 2 | SPD | Speed demand input - accepts PWM (6–100 kHz) or analog voltage (0.7–0.8 V threshold for K version) |
| 3 | RD | Open-drain rotor lock fault indicator - high = locked rotor condition per EEPROM-configured RPM thresholds (RDLOW/RDHIGH) |
| 4–5 | NC | No-connect pins - must remain unconnected per datasheet; no internal bonding |
| 6 | LSS | Low-side source connection - ties to motor star point (Wye) or ground return for current sensing |
| 7 | OUTA | Phase A motor terminal - drives one leg of 3-phase BLDC winding via integrated N-channel MOSFET |
| 8 | VBB | Main supply input (5–16 V) - powers gate drivers and logic; decoupling capacitor required at pin |
| 9 | OUTB | Phase B motor terminal - complements OUTA/OUTC for 3-phase commutation sequence |
| 10–11 | NC | No-connect pins - electrically isolated; no internal connection |
| 12 | OUTC | Phase C motor terminal - completes 3-phase drive; supports DIR-less operation in LP package |
| 13 | LSS | Second low-side source connection - redundant path for improved current return integrity |
| 14 | VCP | Charge pump capacitor node - connects to external 0.1 µF ceramic cap for high-side gate drive voltage generation |
| 15 | CP2 | Secondary charge pump capacitor - works with CP1/VCP to sustain gate drive under high-duty conditions |
| 16 | CP1 | Primary charge pump capacitor - forms bootstrap network with VCP to enable high-side MOSFET switching |
Key Features
| Feature | Design Value |
|---|---|
| Sensorless sinusoidal drive | Eliminates Hall sensors and associated PCB space/cost; reduces vibration via smooth current waveform (not trapezoidal) |
| EEPROM-configurable speed curve | Enables application-specific RPM vs. duty mapping (linear/dual-slope), eliminating need for external MCU firmware |
| I²C serial interface (0x55) | Allows runtime reconfiguration of speed setpoints, protection thresholds, and startup parameters without reflashing |
| Integrated 3 A MOSFET drivers | Reduces BOM count by integrating gate drivers and power switches - no external FETs or gate resistors required |
| Programmable rotor lock detection | Configurable RD output behavior (blank time, delay, RPM thresholds) enables precise fault response in server airflow monitoring |
| Standby mode via SPD pin | Holding SPD low > lock-off time disables motor and reduces quiescent current to ≤100 µA - critical for energy-efficient servers |
Applications
| Server Fan Control | Telecom Base Station Cooling |
|---|---|
|
Use Scenario: High-density 1U/2U rack servers requiring silent, vibration-free airflow at 15,000–25,000 RPM under variable thermal load. IC Role / Device Role / Timing Role: Primary motor controller executing sensorless commutation, closed-loop speed regulation, and tach feedback via FG pin. Use Value: Sinusoidal drive cuts audible noise by >10 dB versus trapezoidal alternatives; EEPROM tuning matches fan curve to thermal profile without firmware changes. |
Use Scenario: Outdoor telecom cabinets with wide ambient temperature swings (–40°C to +70°C) needing reliable forced-air cooling. IC Role / Device Role / Timing Role: Standalone fan driver managing speed via analog SPD voltage or PWM, with thermal shutdown (165°C) preventing overheating in sealed enclosures. Use Value: AEC-Q100 Grade K rating guarantees operation up to +125°C junction temperature; RθJA = 35°C/W enables compact heatsinkless designs. |
| Industrial PC Ventilation | Network Switch Thermal Management |
|
Use Scenario: Fan-cooled industrial PCs deployed in factory automation systems subject to dust, vibration, and EMI. IC Role / Device Role / Timing Role: Fault-tolerant motor controller providing RD lock detection, OCP (6.5 A), and UVLO (4.3 V) to maintain airflow during brownouts or bearing failure. Use Value: Lock-detection blanking (0.1–25.4 s) prevents false trips from startup transients; soft-start minimizes inrush stress on capacitors and connectors. |
Use Scenario: Multi-fan cooling subsystems in Layer 3 switches where individual fan speed must scale with port utilization and ASIC temperature. IC Role / Device Role / Timing Role: Distributed speed controller accepting PWM commands from switch ASIC, reporting RPM via FG, and signaling faults via RD to system manager. Use Value: I²C address 0x55 allows daisy-chaining multiple A5931KESTR-1-J units on same bus; FG output provides accurate tach signal (±20 LSB ADC accuracy) for closed-loop fan control. |
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 RDS(ON) (350 mΩ), no EEPROM, fixed speed curve, 20 V abs max | Lacks programmable lock detection and analog SPD input; suited for cost-sensitive, fixed-speed fans | Choose MP6532GQ-Z when design prioritizes BOM cost over configurability and thermal robustness |
| DRV10983ZRTVT | Lower current rating (2.5 A), no RD fault pin, requires external current sense, 125°C max ambient | Needs external components for overcurrent protection and tach conditioning; less integrated than A5931KESTR-1-J | Choose DRV10983ZRTVT only if existing layout uses QFN-24 and requires TI ecosystem compatibility |
Compared with MP6532GQ-Z and DRV10983ZRTVT, the A5931KESTR-1-J delivers superior integration (on-chip EEPROM, RD fault flag, dual-mode SPD input), higher current capability (3 A), and broader temperature range (–40°C to +125°C), making it optimal for mission-critical server and telecom cooling where reliability and field-programmability are essential.
Availability
A5931KESTR-1-J is available at Aetrix Electronics and suitable for server fan control, telecom base station cooling, and industrial PC ventilation requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.
Supply support for A5931KESTR-1-J 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, serving automotive, industrial, and computing markets since 1989.
The A5931 product line targets high-efficiency, low-noise BLDC fan control in thermally constrained environments, with emphasis on sensorless operation, EEPROM customization, and AEC-Q100 qualification for mission-critical cooling.
FAQ
What is the operating temperature range for the A5931KESTR-1-J?
The A5931KESTR-1-J is rated for –40°C to +125°C ambient operation and is AEC-Q100 qualified as Grade K. This extended range ensures reliable performance in high-temperature server chassis and outdoor telecom enclosures where junction temperatures may reach 165°C before thermal shutdown activates.
Does the A5931KESTR-1-J require external Hall sensors for motor commutation?
No, the A5931KESTR-1-J uses sensorless back-EMF detection for commutation and does not require Hall sensors. Its integrated algorithm enables smooth sinusoidal drive of 3-phase BLDC fans, reducing mechanical vibration and audible noise in server fan applications.
How is speed controlled on the A5931KESTR-1-J?
Speed on the A5931KESTR-1-J is controlled via PWM duty cycle (6–100 kHz) or analog voltage on the SPD pin (0.7–0.8 V threshold for K version). The 9-bit input is mapped to RPM using EEPROM-configurable linear or dual-slope speed curves, enabling precise application-specific fan profiles without an external microcontroller.
What protection features does the A5931KESTR-1-J include?
The A5931KESTR-1-J includes overcurrent protection (6.5 A), thermal shutdown (165°C), supply undervoltage lockout (4.3 V), rotor lock detection with programmable blanking/delay, and short-circuit protection. All protections are hardware-based and do not require software intervention, ensuring fail-safe operation in server cooling systems.
Can the A5931KESTR-1-J be configured after soldering to the PCB?
Yes, the A5931KESTR-1-J supports in-system I²C programming via its FG (SDA) and SPD (SCL) pins using slave address 0x55. Engineers can reconfigure EEPROM parameters-including speed curves, lock thresholds, and startup timing-without removing the device, enabling field calibration and firmware-free updates.
A5931KESTR-1-J Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 24-WFQFN 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:
- 24-QFN (4x4)
A5931KESTR-1-J FAQ
1.How can I place an order for A5931KESTR-1-J through Aetrix?
Please submit a Request for Quotation (RFQ) for A5931KESTR-1-J 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 A5931KESTR-1-J reliable?
The price and inventory of A5931KESTR-1-J are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5931KESTR-1-J is usually 5 days.
3.What payment methods are accepted for A5931KESTR-1-J?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5931KESTR-1-J transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5931KESTR-1-J?
A5931KESTR-1-J orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5931KESTR-1-J 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 A5931KESTR-1-J?
For technical support, including A5931KESTR-1-J datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5931KESTR-1-J requirements.
6.How does Aetrix verify that A5931KESTR-1-J is sourced from the original manufacturer or authorized distributors?
All A5931KESTR-1-J 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 A5931KESTR-1-J meets industry standards.
7.What is the process for return or replacement of A5931KESTR-1-J?
All A5931KESTR-1-J units undergo pre-shipment inspection (PSI). If there is an issue with A5931KESTR-1-J, 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 A5931KESTR-1-J part is unused and in its original packaging.
Return procedure for A5931KESTR-1-J:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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