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Allegro MicroSystems A3940KLPTR-T
- Part No.:
- A3940KLPTR-T
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
A3940KLPTR-T.pdf
- Description:
- IC MOTOR DRIVER 7V-40V 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,809
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Product details
Overview
A3940KLPTR-T from Allegro MicroSystems is a full-bridge power MOSFET controller designed for high-power automotive motor drives. It delivers four high-current gate drive outputs, supports 100% duty cycle operation via integrated charge pump, and provides programmable dead-time (0.3–345 µs), thermal shutdown, and motor lead short-to-battery/short-to-ground fault detection. It operates across –40°C to +150°C junction temperature in automotive under-hood environments.
For engineers reviewing the A3940KLPTR-T datasheet, A3940KLPTR-T pinout, A3940KLPTR-T application, or A3940KLPTR-T equivalent, this page delivers verified technical context, validated pin functions, confirmed automotive motor control use cases, and two documented alternative parts with precise functional and application-level differences.
Technical Context
The A3940KLPTR-T implements dual n-channel MOSFET bridge control using bootstrap gate drive for high-side switches and an internal charge pump enabling true DC (100% duty cycle) operation. Its fault protection architecture monitors VDRAIN and LSS against user-programmable VDSTH thresholds with 1.7 µs noise filtering and two-dead-time settling delay before validation.
Control logic supports forward/reverse direction (PHASE), fast/slow decay (MODE), synchronous rectification (SR), and coast/brake states-all managed through six digital inputs (ENABLE, MODE, SR, PHASE, RESET, LONG) with internal 50 kΩ pull-downs. Dead time is analog-programmed via IDEAD current (4–167 µA) and digitally selected long/short modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VBB Range | 7 V to 40 V input supply - supports 12 V/24 V automotive battery systems with overvoltage protection up to 39 V. |
| VREG13 Output | 13.3 V ±0.7 V regulated supply - powers low-side drivers and charges bootstrap capacitors; dropout voltage ≤0.7 V at 15 mA. |
| Gate Drive Current | 700 mA source / 800 mA sink (25°C) - drives large n-channel MOSFETs with <90 ns rise/<70 ns fall times into 3300 pF load. |
| Dead Time Range | 0.3 µs to 345 µs - programmable via RDEAD (12.1 kΩ–499 kΩ) and LONG pin to prevent shoot-through across wide FET switching speeds. |
| Fault Detection | Short-to-ground, short-to-battery, open-bridge, VBB UV/OV, and thermal shutdown - all asserted on open-drain FAULT pin with latch/clear behavior per fault type. |
| Operating Temp | –40°C to +150°C junction - qualified for under-hood automotive applications with thermal shutdown at 172°C and 12°C hysteresis. |
| Package | 28-pin TSSOP with exposed thermal pad (LP) - RoHS-compliant, matte-tin plated, 4000 pcs/reel tape-and-reel packaging. |
Pinout & Package
28-pin TSSOP package (LP) with exposed thermal pad electrically isolated from GND; optimized for high-power dissipation in automotive motor control PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDRAIN (1) | Kelvin drain monitor | Direct Kelvin connection to high-side MOSFET drains for accurate short-to-ground detection; eliminates PCB trace IR drop error. |
| LSS (2) | Low-side source return | Reference node for short-to-battery monitoring and low-side gate driver return; connects to common source of low-side FETs. |
| GLB (3), GLA (12) | Low-side gate drive outputs | Drive n-channel MOSFET sources; 800 mA sink capability enables fast turn-off and controlled slew rate with external gate resistors. |
| GHB (5), GHA (10) | High-side gate drive outputs | Drive n-channel MOSFET gates via bootstrap; 700 mA source capability sustains gate charge during 100% duty cycle operation. |
| CA/CB (6,9) | Bootstrap capacitor terminals | Positive supply nodes for floating high-side drivers; charged to VREG13 – 1.5 V when Sx is low, then lifted with phase output. |
| VCP (15) | Charge pump output | Regulated VBB + 10.7 V (typ.) - supplies VIN to VREG13 regulator, enabling full-bridge operation down to 7 V battery input. |
| FAULT (18) | Open-drain fault indicator | Asserts logic high on any active fault (latched or transient); pulls low-side drivers to 0 V and forces coast mode when asserted. |
| OVSET (19), VDSTH (28) | Analog threshold inputs | User-programmable pins setting VBB overvoltage trip (16–39 V range) and drain-source fault thresholds (±0.39 V accuracy). |
Key Features
| Feature | Design Value |
|---|---|
| Charge pump + bootstrap gate drive | Enables 100% duty cycle operation with n-channel MOSFETs across 7–40 V battery input without external high-voltage supply. |
| Programmable dead-time control | Adjustable 0.3–345 µs dead time via resistor and LONG pin prevents shoot-through across diverse MOSFET gate charge requirements. |
| Motor lead fault diagnostics | Detects short-to-battery (on GLx active), short-to-ground (on GHx active), and open-bridge conditions with Kelvin VDRAIN sensing. |
| Integrated dual LDOs | VREG13 (13.3 V/15 mA) powers gate drivers; VREG5 (5 V/4 mA) supplies logic and external resistor networks-both with current limiting and UV/OV protection. |
| Automotive-grade thermal management | Thermal shutdown at 172°C with 12°C hysteresis and sleep mode (RESET = 0) reducing quiescent current to 1.0 µA. |
Applications
| Electric Power Steering (EPS) | Automotive HVAC Blower |
|---|---|
Use Scenario: High-reliability bidirectional motor control in steering assist systems requiring continuous torque delivery and fault-safe coasting. IC Role / Device Role / Timing Role: Full-bridge gate driver controlling dual n-channel MOSFET half-bridges; manages PHASE/MODE/SR logic for torque direction, decay mode, and regenerative braking. Use Value: Integrated VDRAIN Kelvin sensing and programmable VDSTH enable precise short-circuit detection in noisy EPS EMI environments without false triggers. | Use Scenario: Variable-speed blower motor control in climate systems where compact size, thermal robustness, and PWM efficiency are critical. IC Role / Device Role / Timing Role: Gate driver IC providing synchronous rectification (SR = 1) and fast/slow decay (MODE) to minimize conduction losses and acoustic noise. Use Value: VREG13-regulated 13.3 V supply ensures stable high-side gate drive across cold-crank (6.5 V) to load-dump (40 V) transients. |
| Engine Cooling Fan | Transmission Valve Actuator |
Use Scenario: High-power radiator fan control subject to extreme under-hood temperatures and battery voltage fluctuations. IC Role / Device Role / Timing Role: Full-bridge controller managing 100% duty cycle operation during maximum cooling demand; uses charge pump to sustain gate voltage at low VBB. Use Value: Thermal shutdown at 172°C and –40°C to +150°C operating range ensure reliability in sustained high-temperature engine bay operation. | Use Scenario: Precision proportional solenoid actuation in automatic transmission shift control requiring rapid, fault-monitored current reversal. IC Role / Device Role / Timing Role: Bidirectional H-bridge driver executing microsecond-accurate PHASE transitions with programmable dead time to prevent solenoid coil shoot-through. Use Value: Adjustable dead time (0.3–345 µs) accommodates varying solenoid inductance and MOSFET switching characteristics across production lots. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar full-bridge MOSFET controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| A3941KLPTR-T | Pin-compatible upgrade with enhanced VBB OVSET resolution (16-step vs. 3-point), improved thermal shutdown accuracy (±5°C), and reduced VREG5 load regulation (2 mV vs. 5 mV). | Supports tighter voltage margining in next-gen automotive modules; maintains identical footprint and control interface. | Select A3941KLPTR-T for new designs requiring higher OV fault granularity and improved regulator stability under dynamic load. |
| TLE9201SG | Infineon's 4-channel high-side/low-side driver with integrated current sense, SPI interface, and ASIL-B compliance; no charge pump or bootstrap support. | Targets safety-critical applications needing diagnostic reporting and functional safety certification; requires external gate supply for n-channel FETs. | Choose TLE9201SG only when ASIL-B compliance, current feedback, or serial configuration are mandatory; not a drop-in replacement. |
Compared with A3940KLPTR-T, A3941KLPTR-T offers refined protection thresholds and regulator performance while maintaining full hardware compatibility; TLE9201SG shifts to a safety-certified, SPI-configurable architecture requiring board-level redesign and external gate supply infrastructure.
Availability
A3940KLPTR-T is available at Aetrix Electronics and suitable for automotive EPS, HVAC blower, engine cooling fan, and transmission actuator applications requiring stable component supply despite end-of-life status.
Supply support for A3940KLPTR-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 sensors and power ICs, specializing in motion control and energy-efficient semiconductor solutions for automotive and industrial markets.
The A3940 product line delivers full-bridge gate drivers for high-power n-channel MOSFET motor control in harsh automotive environments, emphasizing fault resilience, thermal robustness, and programmable protection.
FAQ
Is A3940KLPTR-T still in production?
No, A3940KLPTR-T is a discontinued product. Allegro MicroSystems ceased production as of December 5, 2016. It is not recommended for new design applications, and samples are no longer available. Aetrix Electronics maintains limited legacy stock with full traceability for ongoing production support and repair programs.
What is the function of the VDRAIN pin on A3940KLPTR-T?
The VDRAIN pin on A3940KLPTR-T provides a Kelvin connection to the high-side MOSFET drains for accurate short-to-ground fault detection. It isolates measurement from PCB trace resistance, allowing precise comparison of drain-to-source voltage against the VDSTH threshold without IR drop error-critical for reliable motor protection in noisy automotive systems.
Can A3940KLPTR-T drive p-channel high-side MOSFETs?
No, A3940KLPTR-T is specifically designed to drive n-channel MOSFETs in both high-side (via bootstrap/charge pump) and low-side configurations. Its gate drive architecture-GHA/GHB outputs referenced to VREG13 and CA/CB bootstrap nodes-requires n-channel devices. Driving p-channel high-side FETs would require incompatible voltage referencing and is not supported.
What does the LONG pin do on A3940KLPTR-T?
The LONG pin on A3940KLPTR-T selects between short and long dead-time modes. When LOW (0), dead time is scaled by factor K=1; when HIGH (1), K=32-extending the minimum dead time from 0.3 µs to 8.3 µs and maximum from 11.0 µs to 345 µs. This allows fine-grained shoot-through prevention across diverse MOSFET gate charge profiles.
How is overvoltage protection configured on A3940KLPTR-T?
Overvoltage protection on A3940KLPTR-T is configured via the OVSET pin, which accepts a DC voltage (0–0.9 V) from a resistor divider between VREG5 and GND. Three distinct VBB overvoltage trip points are supported: 16–22 V (OVSET = 0 V), 24–30.5 V (OVSET = 0.45 V), and 32.5–39 V (OVSET = 0.9 V), with 2.1–4.1 V hysteresis.
A3940KLPTR-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushed DC
- Function:
- Controller - Commutation, Direction Management
- Output Configuration:
- Pre-Driver - Half Bridge (2)
- Interface:
- Parallel
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- -
- Voltage - Supply:
- 7V ~ 40V
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 135°C (TA)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
A3940KLPTR-T FAQ
1.How can I place an order for A3940KLPTR-T through Aetrix?
Please submit a Request for Quotation (RFQ) for A3940KLPTR-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 A3940KLPTR-T reliable?
The price and inventory of A3940KLPTR-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3940KLPTR-T is usually 5 days.
3.What payment methods are accepted for A3940KLPTR-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3940KLPTR-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3940KLPTR-T?
A3940KLPTR-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3940KLPTR-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 A3940KLPTR-T?
For technical support, including A3940KLPTR-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3940KLPTR-T requirements.
6.How does Aetrix verify that A3940KLPTR-T is sourced from the original manufacturer or authorized distributors?
All A3940KLPTR-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 A3940KLPTR-T meets industry standards.
7.What is the process for return or replacement of A3940KLPTR-T?
All A3940KLPTR-T units undergo pre-shipment inspection (PSI). If there is an issue with A3940KLPTR-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 A3940KLPTR-T part is unused and in its original packaging.
Return procedure for A3940KLPTR-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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