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Allegro MicroSystems A4934GLPTR-T
- Part No.:
- A4934GLPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A4934GLPTR-T.pdf
- Description:
- IC MOTOR DRIVER 8V-16V 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,142
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Product details
Overview
A4934GLPTR-T from Allegro MicroSystems is a discontinued three-phase sensorless BLDC fan motor driver with BEMF sensing, 16-pin TSSOP package (LP), 8–16 V supply range, 800 mA peak output current, and integrated soft switching for audible noise reduction in cooling applications.
For engineers reviewing the A4934GLPTR-T datasheet, A4934GLPTR-T pinout, A4934GLPTR-T application, or A4934GLPTR-T equivalent, this page provides verified technical context, validated pin functions, confirmed thermal and electrical specs, real-world use cases, and two documented alternative parts for legacy design support and transition planning.
Technical Context
The A4934GLPTR-T implements adaptive BEMF zero-crossing detection using motor center-tap (CTAP) referencing and tri-stated winding sampling, with programmable blanking and commutation delay timers. Its state sequencer executes six-step trapezoidal commutation without Hall sensors.
It integrates charge-pump-based high-side NMOS gate drivers, FG open-drain speed feedback, PWM-controlled duty-cycle speed regulation, and lock-detection logic with 2 s timeout and 5 s auto-restart. Standby mode activates on 500 μs low pulse at PWM.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 8–16 V - supports standard 12 V fan rails with 6.3 V UVLO threshold and 0.56 V hysteresis |
| Peak Output Current | 800 mA - rated for continuous run current <500 mA; 1.25 A only during startup/lock |
| Thermal Resistance (RθJA) | 34 °C/W - measured on 4-layer JEDEC PCB; requires exposed pad soldering and thermal vias |
| BEMF Sensing Method | Center-tap referenced zero-cross detection - eliminates Hall sensors and reduces BOM count |
| FG Output Type | Open-drain - compatible with 3.3 V or 5 V microcontroller inputs via external pull-up |
| Soft Switching Control | SLEW pin selectable (GND = less, open = more) - adjusts slew rate to reduce EMI and acoustic noise |
| Overcurrent Threshold | 200 mV ±20 mV at SENSE pin - sets current limit via external resistor (IOCL = 200 mV / RS) |
Pinout & Package
Package: 16-pin TSSOP with exposed thermal pad (suffix LP); Pb-free, 100% matte tin leadframe plating; requires GND connection to pad and thermal vias for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUTC (1) | Motor phase C output | Half-bridge output terminal for 3-phase BLDC motor winding C |
| CP1 (2), CP2 (3) | Charge pump capacitor terminals | Connect 0.1 μF ceramic caps to enable high-side NMOS gate drive |
| VCP (4) | Charge pump output | Provides boosted gate voltage for high-side drivers; decoupled internally |
| GND (5, 11) | Ground reference | Dual ground pins; must connect to PCB ground plane and exposed thermal pad |
| SLEW (6) | Soft switching control | Logic input: GND = reduced slew, open = enhanced soft switching |
| PWM (7) | Speed and enable control | Active-low PWM input; 500 μs low pulse enters standby mode |
| FG (8) | Fan speed feedback | Open-drain output; pulses per revolution; requires external pull-up resistor |
| TEST (9) | Factory test only | No connection required; leave open-circuit in production designs |
| FC (10) | Force commutation timing | Selects startup oscillator period: GND=100 ms, VBB=50 ms, open=200 ms |
| CTAP (12) | Motor center tap input | Reference node for BEMF zero-cross detection; connects to Y-connected motor center |
| SENSE (14) | Current sense input | Monitors voltage across external sense resistor for overcurrent protection |
| OUTA (15), OUTB (16) | Motor phases A and B outputs | Half-bridge output terminals for remaining motor windings |
| VBB (13) | Power supply input | 8–16 V main supply; requires 10 μF electrolytic decoupling capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Integrated BEMF sensing commutation | Eliminates Hall sensors and associated routing, reducing system cost and board space |
| Adaptive commutation delay | Automatically adjusts timing based on motor BEMF dynamics for stable operation across speed/load |
| Programmable startup oscillator | FC pin selects 50/100/200 ms forced commutation duration to ensure reliable motor start |
| Lock detection with auto-restart | Disables outputs for 5 s after 2 s of missing FG pulses, then attempts restart |
| Low-power standby mode | Reduces quiescent current to ≤50 μA when PWM held low for ≥500 μs |
Applications
| Server Rack Cooling Fan | Industrial Enclosure Ventilation |
|---|---|
Use Scenario: High-reliability 12 V, 3-phase BLDC fans in 1U/2U server chassis requiring silent operation and thermal stability. IC Role / Device Role / Timing Role: Primary motor controller performing sensorless commutation, speed regulation via PWM, and FG-based RPM monitoring. Use Value: Reduces audible noise by >15 dB(A) via soft switching while maintaining 800 mA drive capability for high-static-pressure fans. |
Use Scenario: Fan-cooled PLC cabinets and HMIs operating continuously in ambient temperatures up to +70 °C. IC Role / Device Role / Timing Role: Motor driver with lock detection and thermal shutdown (150 °C TJ) ensuring fail-safe shutdown during blocked airflow or bearing failure. Use Value: Prevents thermal runaway via 15 °C hysteresis thermal shutdown and automatic 5 s recovery attempt after stall detection. |
| Telecom Base Station Heat Sink Fan | Medical Imaging Equipment Cooling |
Use Scenario: Compact, high-efficiency fans in RF power amplifier heat sinks where EMI must be minimized. IC Role / Device Role / Timing Role: PWM-controlled driver with programmable slew rate (SLEW pin) to suppress switching noise coupling into sensitive analog circuits. Use Value: Enables compliance with CISPR 22 Class B emissions limits through adjustable edge rate control without external filtering. |
Use Scenario: Fan assemblies in MRI or CT scanner enclosures requiring long-term reliability and no Hall sensor drift over time. IC Role / Device Role / Timing Role: Sensorless motor controller eliminating magnetic interference risks from Hall sensors near strong magnetic fields. Use Value: Ensures consistent commutation accuracy independent of external magnetic fields, critical for medical device EMC certification. |
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 |
|---|---|---|---|
| A4941 | Pin-compatible successor with disableable soft switching, higher inductance motor support, and updated thermal performance | Required for new designs; supports motors with >1.5 mH phase inductance where A4934GLPTR-T may stall | Select A4941 for new designs or higher-speed/higher-inductance fan motors; migration path is direct with minor layout review. |
| MP6532 | Non-pin-compatible 3-phase driver with integrated MOSFETs, 24 V max, and digital I²C configuration interface | Enables programmable startup profiles and diagnostics not available in A4934GLPTR-T; requires different PCB layout and firmware integration | Choose MP6532 when system-level configurability, fault logging, or extended voltage range (>16 V) is required. |
Compared with A4934GLPTR-T, the A4941 offers backward-compatible pinout and improved motor compatibility, while the MP6532 provides digital control and higher integration at the cost of redesign effort - both serve distinct upgrade paths depending on whether mechanical compatibility or feature expansion is prioritized.
Availability
A4934GLPTR-T is available at Aetrix Electronics and suitable for legacy server cooling, industrial enclosure ventilation, and telecom base station fan applications requiring stable component supply despite end-of-life status.
Supply support for A4934GLPTR-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 ICs, specializing in motion control, current sensing, and motor driver solutions for automotive and industrial markets.
The A4934GLPTR-T belongs to Allegro's sensorless BLDC fan driver product line, engineered specifically for cost-sensitive, high-volume cooling systems requiring Hall-less commutation and low acoustic noise.
FAQ
Is the A4934GLPTR-T still in production?
No, the A4934GLPTR-T is a discontinued product. Allegro officially ended production on October 31, 2011. It is not recommended for new designs, and samples are no longer available. Aetrix Electronics maintains limited legacy stock for existing production continuity under controlled allocation.
What is the function of the FC pin on the A4934GLPTR-T?
The FC pin on the A4934GLPTR-T selects the startup oscillator period: connecting FC to GND sets 100 ms, to VBB sets 50 ms, and leaving it open sets 200 ms. This determines forced commutation duration during initial motor spin-up before BEMF sensing becomes valid - critical for reliable start under load or low-temperature conditions.
Can the A4934GLPTR-T drive a motor without a center tap?
No, the A4934GLPTR-T requires a Y-connected (star-wound) motor with an accessible center tap (CTAP). Its BEMF sensing architecture compares each tri-stated winding voltage to the CTAP reference; delta-connected or center-tap–less motors are incompatible with the A4934GLPTR-T's commutation scheme.
What does the SLEW pin do on the A4934GLPTR-T?
The SLEW pin on the A4934GLPTR-T controls soft switching intensity: grounding it reduces slew rate (less soft switching), while leaving it open increases it (more soft switching). This adjustment directly impacts audible noise and EMI but may cause stall in high-inductance motors - verify with actual motor testing.
How does overcurrent protection work in the A4934GLPTR-T?
The A4934GLPTR-T implements overcurrent protection via the SENSE pin, which monitors voltage across an external resistor (RS). When the sensed voltage exceeds 200 mV ±20 mV, the drivers disable for 25 μs. The trip current is calculated as IOCL = 200 mV / RS - e.g., 0.18 Ω yields ~1.11 A limit.
A4934GLPTR-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:
- Obsolete
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Driver - Fully Integrated, Control and Power Stage
- Output Configuration:
- Half Bridge (3)
- Interface:
- PWM
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- Fan Motor Driver
- Current - Output:
- 500mA
- Voltage - Supply:
- 8V ~ 16V
- Voltage - Load:
- 8V ~ 16V
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-eTSSOP-EP
A4934GLPTR-T FAQ
1.How can I place an order for A4934GLPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A4934GLPTR-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 A4934GLPTR-T reliable?
The price and inventory of A4934GLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A4934GLPTR-T is usually 5 days.
3.What payment methods are accepted for A4934GLPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A4934GLPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A4934GLPTR-T?
A4934GLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A4934GLPTR-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 A4934GLPTR-T?
For technical support, including A4934GLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A4934GLPTR-T requirements.
6.How does Aetrix verify that A4934GLPTR-T is sourced from the original manufacturer or authorized distributors?
All A4934GLPTR-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 A4934GLPTR-T meets industry standards.
7.What is the process for return or replacement of A4934GLPTR-T?
All A4934GLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A4934GLPTR-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 A4934GLPTR-T part is unused and in its original packaging.
Return procedure for A4934GLPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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