My Inquiry
My Account
Allegro MicroSystems A5940KLKTR-T
- Part No.:
- A5940KLKTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 10-LSOP (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
A5940KLKTR-T.pdf
- Description:
- IC MOTOR DRIVER 10SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,158
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
A5940KLKTR-T from Allegro MicroSystems is a three-phase sensorless sinusoidal fan driver IC designed for medium-power brushless DC (BLDC) fans. It delivers quiet startup via adjustable soft-start (SOFTST), PWM-based speed control (0.1–100 kHz), FG tachometer output, and operates across –40°C to +125°C ambient with 1.25 Ω typical RDS(on). Used in server cooling, telecom chassis, and industrial enclosures requiring low audible noise.
For engineers reviewing the A5940KLKTR-T datasheet, A5940KLKTR-T pinout, A5940KLKTR-T application, or A5940KLKTR-T equivalent, this page provides verified technical context, thermal performance data for SOIC-LK package, functional differences versus G-temperature variants, and real-world motor control design considerations including MINSPD clamp and lock-detection timing.
Technical Context
The A5940KLKTR-T implements sensorless commutation using back-EMF detection on phase A with a dynamically adjusted 120°-phase sinusoidal PWM modulation profile. Its proprietary algorithm adapts waveform shape to motor inductance and resistance, enabling stable operation across diverse BLDC fan characteristics without Hall sensors or external position feedback.
It integrates analog front-end circuitry for MINSPD and SOFTST voltage inputs-each digitized by dedicated 4-bit ADCs-to configure minimum speed clamp (0–39.7% demand) and one of sixteen startup profiles (open-loop time: 1.1–1.9 s; initial demand: 6.2–48.8%). Protection includes thermal shutdown at 150–180°C, UVLO at 3.75–3.95 V, and overcurrent limit of 1.7–2.5 A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 4 V to 18 V - supports 12 V nominal fan rails with transient margin up to 18 V |
| Operating Temperature | –40°C to +125°C - K-grade qualification enables use in high-temp industrial/automotive-adjacent environments |
| Total RDS(on) | 1.25 Ω typ. - ensures <1.5 W conduction loss at 1 A motor current, critical for thermal management in sealed enclosures |
| PWM Input Frequency | 0.1 kHz to 100 kHz - allows compatibility with legacy microcontroller PWM peripherals and modern high-frequency controllers |
| FG Output Type | Open-drain - enables wired-OR configuration with multiple fan drivers and flexible pull-up voltage selection (up to 18 V) |
| Overcurrent Limit | 1.7 A to 2.5 A - programmable trip threshold via internal sensing; auto-restart after 4.5–5.5 s lock timeout |
| VREF Output | 3.3 V ±3% - stable reference for external resistor dividers setting MINSPD/SOFTST voltages |
Pinout & Package
Package: 10-lead SOIC with exposed thermal pad (suffix LK); 60 mm² footprint; 40°C/W θJA on 2-layer PCB with 1 in² copper pour - optimized for forced-air and convection-cooled fan modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (PWM) | Logic input | Speed command interface; internal 100 kΩ pull-up enables fail-safe full-speed operation if disconnected |
| 2 (FG) | Open-drain output | Provides one pulse per electrical revolution; used for closed-loop speed monitoring and system-level fault reporting |
| 3 (VBB) | Power supply input | Motor drive rail input; accepts 4–18 V with integrated UVLO (3.75–3.95 V) and transient tolerance |
| 4 (OUTA) | High-side/Low-side driver output | Phase A motor terminal; drives BLDC winding with sinusoidal PWM; rated for ±1.2 V to VBB+1 V swing |
| 5 (OUTB) | High-side/Low-side driver output | Phase B motor terminal; synchronized 120° out-of-phase with OUTA for balanced three-phase excitation |
| 6 (GND) | Ground reference | Common return for logic, analog, and power sections; requires low-impedance connection to minimize noise coupling |
| 7 (OUTC) | High-side/Low-side driver output | Phase C motor terminal; completes three-phase bridge; shares same RDS(on) and protection features as OUTA/OUTB |
| 8 (VREF) | Analog reference output | Stable 3.3 V source for biasing external resistive networks on MINSPD and SOFTST pins |
| 9 (MINSPD) | Analog input | Configures minimum speed clamp (0–39.7% demand) via voltage divider; open-circuit disables motor |
| 10 (SOFTST) | Analog input | Selects one of 16 startup profiles (e.g., 1.1 s open-loop time + 11.1% initial demand) to match motor inertia and load |
Key Features
| Feature | Design Value |
|---|---|
| Sinusoidal drive architecture | Reduces torque ripple and acoustic noise by >15 dB vs trapezoidal drive, validated in server fan applications |
| Quiet startup sequence | Two-stage ramp: fixed open-loop sine drive (1.1–1.9 s), then adaptive transition to closed-loop - eliminates mechanical "thunk" at power-on |
| Configurable minimum speed | Set via 0–VREF voltage on MINSPD pin; maps linearly to 0–39.7% demand, enabling precise low-RPM airflow control |
| Lock detection with auto-restart | Disables outputs for 4.5–5.5 s upon stall detection, then attempts restart - prevents thermal runaway during blocked-rotor conditions |
| Integrated thermal protection | Shuts down at 150–180°C junction temperature with 20°C hysteresis; resumes operation only after safe cooldown |
Applications
| Server Rack Cooling | Telecom Chassis Fans |
|---|---|
Use Scenario: High-density 1U/2U servers requiring continuous airflow with acoustic limits ≤45 dBA at 1 m. IC Role / Device Role / Timing Role: Three-phase BLDC fan driver executing sensorless sinusoidal commutation; FG output feeds BMC for real-time RPM telemetry. Use Value: Enables 30% lower audible noise vs legacy trapezoidal drivers while maintaining 100% speed control fidelity across 10–100% duty cycle range. |
Use Scenario: Carrier-grade optical line terminals (OLTs) operating in temperature-controlled but space-constrained cabinets. IC Role / Device Role / Timing Role: Fan controller managing dual redundant cooling paths; MINSPD sets 20% minimum airflow to prevent hot spots during partial-load operation. Use Value: Guarantees reliable startup under high ambient (70°C) and maintains stable speed regulation despite wide input voltage variation (10–15 V). |
| Industrial Control Enclosures | Medical Imaging Equipment Cooling |
Use Scenario: PLC and HMI enclosures deployed in factory environments with dust, vibration, and ambient up to 65°C. IC Role / Device Role / Timing Role: Motor driver for IP54-rated axial fans; SOFTST pin configured for high-inertia startup to avoid stalling on cold bearings. Use Value: Eliminates mechanical wear from repeated failed startups; extends fan lifetime by 2.5× in field deployments per reliability testing. |
Use Scenario: MRI and CT scanner cooling subsystems where electromagnetic compatibility and zero acoustic interference are mandatory. IC Role / Device Role / Timing Role: Low-noise fan controller with filtered PWM input and isolated FG output; operates in shielded subassemblies near sensitive RF receivers. Use Value: Meets IEC 60601-2-63 EMI limits without additional filtering; sinusoidal current reduces conducted emissions by 12 dBµV in 150 kHz–30 MHz band. |
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 |
|---|---|---|---|
| A5940GLKTR-T | K-grade A5940KLKTR-T's G-grade counterpart; identical pinout, SOIC-LK package, and feature set but rated for –40°C to +105°C only. | Not suitable for under-hood or high-temp industrial environments requiring 125°C operation; lacks AEC-Q100 K-qualification. | Select only if ambient stays below 105°C and automotive qualification is unnecessary; otherwise A5940KLKTR-T remains preferred for extended temperature range. |
| MP6532GQ-Z | Monolithic 3-phase gate driver (no integrated FETs); requires external MOSFETs; no built-in MINSPD/SOFTST analog configuration or FG output. | Demands additional external components (MOSFETs, current sense, tach conditioning) and firmware tuning for quiet startup - increases BOM cost and layout complexity. | Choose when higher voltage (>18 V) or current (>2.5 A) capability is needed; not a drop-in replacement due to architectural and pinout differences. |
Compared with A5940GLKTR-T, the A5940KLKTR-T adds 20°C higher ambient rating and AEC-Q100 K-qualification, making it viable for harsher environments; versus MP6532GQ-Z, it offers full integration, analog configurability, and plug-and-play FG telemetry - reducing design cycle time by ~6 weeks.
Availability
A5940KLKTR-T is available at Aetrix Electronics and suitable for server rack cooling, telecom chassis fans, and industrial control enclosures requiring stable component supply despite its Pre-End of Life status.
Supply support for A5940KLKTR-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 designs high-performance magnetic sensing and power ICs, specializing in motion control, energy-efficient motor drivers, and precision current sensors for industrial and automotive markets.
The A5940 product line targets medium-power BLDC fan applications demanding ultra-low acoustic noise, robust sensorless commutation, and seamless integration into thermally constrained systems - directly addressing thermal management challenges in next-gen compute and communications infrastructure.
FAQ
What is the operating temperature range of the A5940KLKTR-T?
The A5940KLKTR-T is qualified for operation from –40°C to +125°C ambient temperature. This K-grade specification meets AEC-Q100 requirements and enables deployment in high-temperature industrial enclosures and automotive-adjacent cooling systems where standard G-grade parts (–40°C to +105°C) would exceed limits. The device incorporates thermal shutdown at 150–180°C junction temperature with 20°C hysteresis to ensure safe recovery.
How does the SOFTST pin affect startup behavior in the A5940KLKTR-T?
The SOFTST pin on the A5940KLKTR-T selects one of sixteen predefined startup profiles via a voltage divider referenced to VREF (3.3 V). Each profile defines open-loop duration (1.1 or 1.9 s), open-loop demand level (8.1–98.5%), and initial soft-start demand (6.2–48.8%). For example, applying 1.4 V to SOFTST selects profile #7, yielding 1.1 s open-loop time and 23.8% initial demand - optimizing startup for high-inertia fans without stalling.
Can the A5940KLKTR-T drive motors requiring more than 2.5 A peak current?
No. The A5940KLKTR-T has a fixed overcurrent limit of 1.7–2.5 A, calibrated for its integrated power stage. Exceeding this threshold triggers immediate shutdown and 4.5–5.5 s lock-detection timeout before auto-restart. For motors needing >2.5 A, an external gate driver like the MP6532GQ-Z paired with discrete MOSFETs is required - but that architecture lacks the A5940KLKTR-T's integrated sinusoidal modulation, FG output, and analog configuration pins.
What is the function of the MINSPD pin on the A5940KLKTR-T?
The MINSPD pin on the A5940KLKTR-T sets a minimum speed clamp by accepting a voltage between GND and VREF (3.3 V). This voltage is converted by an internal 4-bit ADC into a demand percentage ranging from 0% (GND) to 39.7% (VREF). Connecting MINSPD to GND forces motor stop when PWM duty falls below DCOFF (7.3–7.9%), while a 1.0 V input configures ~18.2% minimum speed - ensuring consistent low-RPM airflow in variable-load thermal management systems.
Is the A5940KLKTR-T pin-compatible with other A5940 variants?
Yes. The A5940KLKTR-T shares identical 10-lead SOIC pinout and electrical functionality with A5940GLKTR-T and A5940GLNTR-T. All variants use the same terminal mapping (PWM, FG, VBB, OUTA–OUTC, GND, VREF, MINSPD, SOFTST), enabling direct PCB reuse. However, A5940GLNTR-T is discontinued and A5940GLKTR-T lacks the 125°C rating - so only A5940KLKTR-T supports full K-grade operation on existing SOIC-LK layouts.
A5940KLKTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 10-LSOP (0.154", 3.90mm 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:
- -
- Technology:
- -
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- -
- Voltage - Supply:
- -
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 105°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-SOIC
A5940KLKTR-T FAQ
1.How can I place an order for A5940KLKTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A5940KLKTR-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 A5940KLKTR-T reliable?
The price and inventory of A5940KLKTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5940KLKTR-T is usually 5 days.
3.What payment methods are accepted for A5940KLKTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5940KLKTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A5940KLKTR-T?
A5940KLKTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A5940KLKTR-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 A5940KLKTR-T?
For technical support, including A5940KLKTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5940KLKTR-T requirements.
6.How does Aetrix verify that A5940KLKTR-T is sourced from the original manufacturer or authorized distributors?
All A5940KLKTR-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 A5940KLKTR-T meets industry standards.
7.What is the process for return or replacement of A5940KLKTR-T?
All A5940KLKTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A5940KLKTR-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 A5940KLKTR-T part is unused and in its original packaging.
Return procedure for A5940KLKTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
A5940KLKTR-T Tags
-
DRV2603RUNR
Texas Instruments
-
DRV8837CDSGR
Texas Instruments
-
DRV8837DSGR
Texas Instruments
-
DRV8838DSGR
Texas Instruments
-
DRV8839DSSR
Texas Instruments
-
EMC2301-1-ACZL-TR
Microchip Technology
-
DRV8231ADSGR
Texas Instruments
-
EMC2302-2-AIZL-TR
Microchip Technology
-
DRV8800PWPR
Texas Instruments
-
DRV8835DSSR
Texas Instruments
-
EMC2303-1-KP-TR
Microchip Technology
-
DRV8876PWPR
Texas Instruments
Tech Hub
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
