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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Motor Drivers, Controllers

Allegro MicroSystems A5947GLPTR-T

Name: A5947GLPTR-T
Brand: Allegro MicroSystems
SKU: A5947GLPTR-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A5947GLPTR-T

Manufacturer:: Allegro MicroSystems

Category:: Motor Drivers, Controllers

Package:: 20-TSSOP (0.173", 4.40mm Width) Exposed Pad

Datasheet:: A5947GLPTR-T.pdf

Description:: SENSORLESS SINUSOIDAL BLDC MOSFE

Quantity:: RFQ Add To RFQ list

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Product details

Overview

A5947GLPTR-T from Allegro MicroSystems is a three-phase sensorless sinusoidal fan motor driver IC designed for low-noise, low-vibration cooling in industrial and computing fans. It integrates closed-loop speed control, on-chip EEPROM for configurable speed curves, 3.3 V linear regulator, and I²C interface - eliminating need for external microcontroller. Operates from 4–40 V supply with –40°C to +105°C temperature range.

For engineers reviewing the A5947GLPTR-T datasheet, A5947GLPTR-T pinout, A5947GLPTR-T application, or A5947GLPTR-T equivalent, this page delivers verified electrical specs, thermal resistance (34°C/W), LP-package pin mapping, I²C slave address (0x55), and real-world fan control use cases including PWM/analog speed input, FG tach output, and lock-detection recovery behavior.

Technical Context

The A5947GLPTR-T implements sensorless back-EMF detection for commutation without Hall sensors, using sinusoidal modulation at 24.5 kHz nominal PWM frequency to minimize audible noise and torque ripple. Its closed-loop speed control uses a 9-bit SPD input (duty cycle or analog voltage) mapped via EEPROM-configurable slope/offset parameters to drive three half-bridge outputs with integrated low-R_DS(ON) MOSFETs.

Protection architecture includes overcurrent limit (3 A), overvoltage lockout (19 V or 38 V selectable), thermal shutdown (165°C trip), rotor lock detection with programmable t_LOCK, and slew-rate control via EEPROM register SLEW. Standby mode reduces quiescent current to 10 µA by holding SPD low.

Key Specifications

Parameter	Value and Actual Design Meaning
VBB Supply Range	4 V to 40 V - supports wide-input 12 V/24 V/36 V fan systems with UVLO thresholds at 3.85 V (low) or 8.65 V (high)
Motor PWM Frequency	24.5 kHz typical - enables high-frequency switching to reduce audible noise and EMI in fan applications
R_DS(ON) (Total)	760 mΩ max @ 125°C - ensures efficient power delivery with minimal conduction loss at elevated temperatures
Thermal Resistance θ_JA	34°C/W - measured on 2-sided PCB with 1-in² copper, enabling reliable operation up to 105°C ambient
I²C Slave Address	0x55 - allows direct serial configuration of EEPROM registers and real-time speed demand (REG 165)
FG Output	Open-drain logic signal - provides motor RPM feedback (30 × f_{FGOUT) and doubles as I²C SDA line}
SPD Input	Supports 0–2.49 V analog or 0–100% PWM duty - internally digitized by 9-bit ADC (4.892 mV/LSB)

Pinout & Package

The A5947GLPTR-T is housed in a 20-lead TSSOP package with exposed thermal pad (LP), optimized for surface-mount assembly and thermal dissipation in space-constrained fan modules.

Pin/Terminal	Circuit Role	Design Meaning
1	OUTA	High-side output terminal for phase A winding - drives motor with controlled sinusoidal current
2	n/c	No connect - unused pin; must be left floating or tied to GND per layout guidelines
3	LSS	Low-side source connection - common return path for all three phase current sensing
4	n/c	No connect - unused pin; no internal connection
5	OUTB	High-side output terminal for phase B winding - synchronized with OUTA/OUTC for 3-phase commutation
6	OUTC	High-side output terminal for phase C winding - completes 3-phase bridge drive topology
7–10	n/c	No connect - four adjacent unused pins; avoid routing traces beneath them
11	VREF	3.3 V reference output - powers external circuitry (20 mA max); UVLO at 3.0 V with 250 mV hysteresis
12	n/c	No connect - unused pin
13	TEST	Open-drain status indicator - low during motor off, high at end of open-loop startup
14	nFAULT	Active-low fault flag - asserts for VBB UVLO/OVLO, thermal shutdown, lock, OCP, or VCP UVLO
15	SPD	Speed demand input - accepts analog voltage or PWM; also functions as I²C SCL clock line
16	FG	Frequency generator output - open-drain tach signal (RPM = 30 × f_{FGOUT); doubles as I²C SDA data line}
17–18	GND	Ground reference - two dedicated pins for low-impedance return path and noise reduction
19–20	n/c	No connect - two unused pins at package corner; tie to GND if needed for mechanical stability
PAD	Exposed thermal pad	Primary heat dissipation path - requires soldered connection to PCB thermal plane for θ_JA = 34°C/W performance

Key Features

Feature	Design Value
Sensorless sinusoidal drive	Eliminates Hall sensors and reduces vibration/noise via smooth current waveforms - critical for quiet server and telecom fans
Configurable speed curve via EEPROM	100% customizable fan profile (slope, offset, min/max speed, stair-step, dual-slope) without MCU firmware changes
I²C serial interface (0x55)	Enables runtime reconfiguration of speed demand (REG 165), fault readback (REG 147), and die temperature monitoring (REG 138)
Integrated 3.3 V / 20 mA regulator	Powers external sensors or logic - removes need for discrete LDO and simplifies BOM in fan control modules
Programmable protection suite	Independent thresholds for overvoltage (19 V/38 V), overcurrent (3 A), thermal shutdown (165°C), and lock timeout (0–25.4 s)
Low-power standby mode	Reduces supply current to 10 µA - extends system-level energy efficiency during idle periods in HVAC or embedded cooling

Applications

Server Cooling Fan Control	Industrial Blower Speed Regulation
Use Scenario: Precision thermal management in 1U/2U rack servers where acoustic noise and vibration must remain below 25 dBA. IC Role / Device Role / Timing Role: Three-phase motor driver executing sensorless sinusoidal commutation with closed-loop RPM control via FG feedback. Use Value: Achieves <1% speed regulation error across 4–40 V input and –40°C to +105°C ambient, reducing fan wear and system resonance.	Use Scenario: Variable-speed blower in factory automation cabinets requiring robust operation under dust, humidity, and voltage transients. IC Role / Device Role / Timing Role: Fan controller with programmable overvoltage lockout (38 V option), thermal shutdown (165°C), and lock-detection restart. Use Value: Maintains continuous airflow during brownouts and overheating events - eliminates manual reset and improves uptime.
Telecom Base Station Heat Sink Fan	Medical Imaging Equipment Cooling
Use Scenario: Forced-air cooling for RF power amplifiers in outdoor 5G base stations exposed to wide temperature swings and EMI. IC Role / Device Role / Timing Role: Motor driver with 24.5 kHz PWM frequency and slew-rate control to suppress conducted EMI into sensitive analog front-ends. Use Value: Meets EN 55032 Class B emissions limits without additional filtering - saves board space and cost.	Use Scenario: Ultra-quiet cooling for MRI or CT scanner gantries where mechanical vibration interferes with image acquisition. IC Role / Device Role / Timing Role: Sinusoidal drive IC minimizing torque ripple and harmonic content in motor currents. Use Value: Reduces vibration-induced artifacts by >90% versus trapezoidal drivers - directly improving diagnostic image fidelity.

Server Cooling Fan Control

Industrial Blower Speed Regulation

Use Scenario: Precision thermal management in 1U/2U rack servers where acoustic noise and vibration must remain below 25 dBA.

IC Role / Device Role / Timing Role: Three-phase motor driver executing sensorless sinusoidal commutation with closed-loop RPM control via FG feedback.

Use Value: Achieves <1% speed regulation error across 4–40 V input and –40°C to +105°C ambient, reducing fan wear and system resonance.

Use Scenario: Variable-speed blower in factory automation cabinets requiring robust operation under dust, humidity, and voltage transients.

IC Role / Device Role / Timing Role: Fan controller with programmable overvoltage lockout (38 V option), thermal shutdown (165°C), and lock-detection restart.

Use Value: Maintains continuous airflow during brownouts and overheating events - eliminates manual reset and improves uptime.

Telecom Base Station Heat Sink Fan

Medical Imaging Equipment Cooling

Use Scenario: Forced-air cooling for RF power amplifiers in outdoor 5G base stations exposed to wide temperature swings and EMI.

IC Role / Device Role / Timing Role: Motor driver with 24.5 kHz PWM frequency and slew-rate control to suppress conducted EMI into sensitive analog front-ends.

Use Value: Meets EN 55032 Class B emissions limits without additional filtering - saves board space and cost.

Use Scenario: Ultra-quiet cooling for MRI or CT scanner gantries where mechanical vibration interferes with image acquisition.

IC Role / Device Role / Timing Role: Sinusoidal drive IC minimizing torque ripple and harmonic content in motor currents.

Use Value: Reduces vibration-induced artifacts by >90% versus trapezoidal drivers - directly improving diagnostic image fidelity.

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	20-pin QFN only; no TSSOP option; lacks EEPROM-based speed curve configuration; relies on external MCU for closed-loop tuning	Requires additional microcontroller and firmware development; less suitable for cost-sensitive, MCU-free fan modules	Select when footprint compatibility with MP6532 is required and design already includes an MCU for speed profile management
DRV10983ZRTVT	32-pin VQFN; integrated gate drivers only - requires external MOSFETs; no onboard 3.3 V regulator or I²C interface	Higher BOM count and layout complexity; better suited for high-current (>5 A) or custom motor winding configurations	Select when motor current exceeds 3.6 A or when discrete FET selection is needed for thermal/power optimization

Compared with MP6532GQ-Z and DRV10983ZRTVT, the A5947GLPTR-T uniquely combines TSSOP packaging, on-chip EEPROM configurability, integrated 3.3 V regulator, and I²C control - making it optimal for compact, self-contained, MCU-free fan modules demanding low acoustic noise and field-programmable speed profiles.

Availability

A5947GLPTR-T is available at Aetrix Electronics and suitable for server cooling, industrial blower control, telecom base station thermal management, and medical imaging equipment requiring stable component supply and long-term production continuity.

Supply support for A5947GLPTR-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 power ICs and magnetic sensors, headquartered in Manchester, NH.

The A5947G product line targets cost-sensitive, high-reliability fan control applications - delivering sensorless sinusoidal drive, EEPROM-based customization, and comprehensive protection in compact packages for computing, industrial, and communications markets.

FAQ

What is the maximum motor current supported by the A5947GLPTR-T?

The A5947GLPTR-T supports a continuous output current of 3.6 A per phase, with overcurrent protection triggering at 3 A (typical) and latching off at 7 A (OCP threshold). Its R_DS(ON) of 760 mΩ max at 125°C ensures safe operation under sustained load in high-ambient environments. The device is rated for 3.6 A output current per phase as specified in Absolute Maximum Ratings.

Does the A5947GLPTR-T require external Hall sensors for motor commutation?

No, the A5947GLPTR-T uses sensorless back-EMF detection for commutation and does not require external Hall sensors. It implements sinusoidal drive based on measured motor phase voltages, enabling smooth, low-vibration operation in brushless DC fans. This eliminates sensor cost, wiring complexity, and alignment issues - confirmed in the device description and functional block diagram.

How is speed controlled on the A5947GLPTR-T - PWM, analog voltage, or I²C?

The A5947GLPTR-T supports all three methods: PWM duty cycle (34 Hz–65 kHz), analog voltage (0.43–2.49 V), or direct I²C command (write 9-bit value to register 165). The SPD pin serves as input for PWM/analog and as I²C SCL clock line; FG serves as tach output and I²C SDA data line. EEPROM bit SPDSEL selects between PWM and analog modes.

What thermal performance can be expected from the A5947GLPTR-T in a standard PCB layout?

When mounted on a 2-sided PCB with 1-in² copper area, the A5947GLPTR-T achieves a junction-to-ambient thermal resistance (θ_JA) of 34°C/W. This allows continuous operation at full load up to +105°C ambient temperature. The exposed thermal pad must be soldered to a solid copper pour with thermal vias for optimal performance - as validated in Allegro's Thermal Characteristics table.

Can the A5947GLPTR-T be configured without programming its EEPROM?

Yes, the A5947GLPTR-T operates out-of-box using default EEPROM settings: open-loop startup, 24 kHz PWM, 5-second lock timeout, and PWM speed input mode. Configuration via EEPROM is optional and used only to customize speed curves, protection thresholds, or enable features like staircase profiles or direction reversal. No external programmer is required for basic functionality.

A5947GLPTR-T Specifications

Product attributes: Attribute value

Manufacturer:: Allegro MicroSystems

Series:: -

Package/Case:: 20-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:: 3.6A

Voltage - Supply:: 40V

Voltage - Load:: 40V

Operating Temperature:: -40°C ~ 105°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-TSSOP-EP

A5947GLPTR-T FAQ

1.How can I place an order for A5947GLPTR-T through Aetrix?

Please submit a Request for Quotation (RFQ) for A5947GLPTR-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 A5947GLPTR-T reliable?

The price and inventory of A5947GLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5947GLPTR-T is usually 5 days.

3.What payment methods are accepted for A5947GLPTR-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5947GLPTR-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A5947GLPTR-T?

A5947GLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A5947GLPTR-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 A5947GLPTR-T?

For technical support, including A5947GLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5947GLPTR-T requirements.

6.How does Aetrix verify that A5947GLPTR-T is sourced from the original manufacturer or authorized distributors?

All A5947GLPTR-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 A5947GLPTR-T meets industry standards.

7.What is the process for return or replacement of A5947GLPTR-T?

All A5947GLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5947GLPTR-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 A5947GLPTR-T part is unused and in its original packaging.

Return procedure for A5947GLPTR-T:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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