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Allegro MicroSystems A3935KLQTR
- Part No.:
- A3935KLQTR
- Manufacturer:
- Allegro MicroSystems
- Category:
- Motor Drivers, Controllers
- Package:
- 36-BSOP (0.295", 7.50mm Width)
- Datasheet:
-
A3935KLQTR.pdf
- Description:
- IC MOTOR DRVR 4.75V-5.25V 36QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,835
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Product details
Overview
The A3935KLQTR from Allegro MicroSystems is a 3-phase N-channel MOSFET gate driver IC designed for automotive high-power motor control. It integrates a PFM boost converter (16 V nominal), internal LDO regulator (13.5 V VREG), six TTL-compatible gate drive outputs, differential current sensing, and comprehensive fault protection including short-to-battery/ground, bridge-open, and thermal shutdown. It operates across –40°C to 150°C junction temperature in electric power steering and HVAC blower systems.
For engineers reviewing the A3935KLQTR datasheet, A3935KLQTR pinout, A3935KLQTR application, or A3935KLQTR equivalent, this page delivers verified technical context, validated pin functions, real-world automotive use cases, and two confirmed alternative controllers with documented functional differences.
Technical Context
The A3935KLQTR implements a pulse-frequency modulated (PFM) boost converter to generate a stable ~16 V VBOOST supply from a wide 7–40 V battery input, enabling reliable high-side N-MOSFET drive via bootstrap circuits. Its integrated differential current-sense amplifier (gain = 19.2 V/V, ±25 mV DC error) supports Kelvin-connected shunts for accurate phase-current monitoring.
Fault management includes independent VBAT overvoltage (adjustable 19.4–40 V via OVSET), undervoltage (5.25 V trip), VREG undervoltage (10.5 V), and motor-lead diagnostics using VDSTH-set thresholds and Kelvin-connected VDRAIN/LSS inputs. Dead-time control (75–180 ns) prevents shoot-through during phase commutation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Battery Input Range | 7 V to 40 V - supports cold-crank and load-dump conditions in 12 V automotive systems. |
| VREG Output Voltage | 12.7–14 V - regulated high-side gate supply enabling robust N-MOSFET turn-on even at low VBAT. |
| Gate Drive Outputs | 6 TTL-compatible outputs (GHA/GLA–GHC/GLC) - direct phase-A/B/C high/low-side control with 800 mA pulsed source/sink capability. |
| Current Sense Gain | 19.2 V/V ±0.3 - precise proportional output (CSOUT) for closed-loop motor current regulation. |
| Operating Temperature | –40°C to 150°C TJ - qualified for under-hood automotive environments per AEC-Q100. |
| Protection Features | Short-to-battery, short-to-ground, bridge-open, VBAT UV/OV, VREG UV, VDD UV, thermal shutdown - autonomous fault detection with active-low FAULT output. |
| Package | 36-pin QSOP (LQ), 0.8 mm pitch - surface-mount package with exposed pad thermal path (RθJA = 44°C/W). |
Pinout & Package
Package: 36-pin QSOP (LQ), 0.8 mm pitch, surface-mount, Pb-free variant with 100% matte tin leadframe plating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CSP / CSN | Differential current-sense inputs | Kelvin connection across shunt resistor; enables accurate phase-current measurement with ±200 mV common-mode range. |
| GHA–GHC / GLA–GLC | High-/low-side gate drive outputs | Drive external N-MOSFET gates; GHx sourced up to 800 mA, GLx sunk up to 850 mA at 25°C. |
| CA–CC | Bootstrap capacitor positive terminals | Supply floating high-side drivers; voltage rises with SA/SB/SC to maintain VGS > 10 V for N-FETs. |
| VDSTH / VDRAIN | Drain-source fault threshold & Kelvin monitor | VDSTH sets MOSFET on-state VDS fault threshold; VDRAIN provides isolated Kelvin sense for high-side drain voltage. |
| OVSET / OVFLT / UVFLT | VBAT overvoltage setpoint & fault flags | OVSET adjusts VBAT(OV) from 19.4–40 V; OVFLT/UVFLT provide open-drain status signals for system-level fault handling. |
| ENABLE / AHI–CLO | Global enable & phase control inputs | ENABLE disables all drivers; TTL-compatible AHI/ALO etc. allow direct microcontroller PWM or logic-level phase control. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PFM boost converter | Generates stable ~16 V VBOOST from 7–40 V battery input-enables high-side N-MOSFET drive without external boost IC. |
| Bootstrap circuitry with refresh | Supports continuous high-side conduction via CBOOT charge/discharge; 2.0 μs refresh time ensures gate voltage stability at high PWM frequencies. |
| Differential current-sense amplifier | 19.2 V/V gain, ±25 mV offset error, 1.6 MHz bandwidth-delivers accurate, noise-immune motor current feedback for torque control. |
| Comprehensive motor-lead diagnostics | Monitors short-to-battery (via LSS), short-to-ground (via VDRAIN), and bridge-open faults-reduces need for external protection circuitry. |
| AEC-Q100 qualified operation | –40°C to 150°C TJ range with thermal shutdown at 170°C-meets automotive reliability requirements for EPS and HVAC applications. |
Applications
| Electric Power Steering (EPS) | HVAC Blower Motor Control |
|---|---|
Use Scenario: High-torque, safety-critical steering assist in passenger vehicles requiring fail-safe motor control under battery transients. IC Role / Device Role / Timing Role: 3-phase gate driver with integrated VBAT monitoring, current sensing, and fault reporting-serves as core motor interface between MCU and 3-phase inverter bridge. Use Value: Enables single-chip motor control with diagnostic coverage for ASIL-B compliance; eliminates discrete boost and sense amplifiers. | Use Scenario: Variable-speed cabin air circulation in automotive HVAC systems with variable load and thermal constraints. IC Role / Device Role / Timing Role: Gate driver with adjustable VBAT overvoltage threshold and thermal shutdown-manages fan motor startup, speed regulation, and overtemperature protection. Use Value: Reduces BOM count by integrating bootstrap, current sense, and fault logic; supports smooth ramp-up/ramp-down via ENABLE-controlled coasting. |
| Engine Cooling Fan Control | Hybrid/EV Auxiliary Motor Drives |
Use Scenario: Radiator cooling fan operation across wide ambient temperatures and battery voltages (e.g., stop-start systems). IC Role / Device Role / Timing Role: High-current 3-phase driver with VBAT undervoltage lockout (5.25 V) and dead-time control-ensures safe fan operation during cranking. Use Value: Maintains fan functionality down to 7 V battery input; built-in UV/OV protection avoids false trips during load dump. | Use Scenario: Low-power auxiliary drives such as oil pumps, water pumps, or compressor actuators in hybrid powertrains. IC Role / Device Role / Timing Role: Compact gate driver with integrated LDO (VREG) and diagnostic outputs-interfaces MCU to small 3-phase inverter with minimal external components. Use Value: Supports compact, thermally efficient designs with 44°C/W thermal resistance; FAULT/UVFLT/OVFLT simplify system-level fault logging. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-phase gate driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP6532GQ-Z | Integrated 3-phase gate driver with 60 V half-bridge outputs; no internal boost converter-requires external 12 V supply for high-side drive. | Lacks PFM boost and bootstrap refresh; suited for 24 V industrial systems where external supply is available. | Select MP6532GQ-Z only when external 12 V rail exists and automotive AEC-Q100 qualification is not required. |
| DRV8305PAPR | 3-phase smart gate driver with integrated FETs (60 V, 3.5 A); includes SPI interface and enhanced diagnostics but no VBAT overvoltage adjustment. | Contains power stage-eliminates external MOSFETs but increases thermal footprint; lacks programmable OVSET. | Choose DRV8305PAPR for space-constrained designs needing integrated FETs and digital configuration, not analog VBAT fault tuning. |
Compared with MP6532GQ-Z and DRV8305PAPR, the A3935KLQTR uniquely combines automotive-grade PFM boost, adjustable VBAT OV threshold, and standalone gate drive in a 36-pin QSOP-making it optimal for cost-sensitive, high-reliability 12 V automotive motor control where external supplies or digital interfaces are undesirable.
Availability
A3935KLQTR is available at Aetrix Electronics and suitable for electric power steering, HVAC blower control, and engine cooling fan applications requiring stable component supply across extended automotive temperature ranges and long production lifecycles.
Supply support for A3935KLQTR 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 semiconductor company specializing in magnetic sensing, power ICs, and motor control solutions for automotive and industrial markets.
The A3935KLQTR belongs to Allegro's automotive gate driver product line, engineered specifically for high-reliability 3-phase brushless DC motor control in safety-critical vehicle subsystems like steering and thermal management.
FAQ
What is the maximum battery voltage the A3935KLQTR can withstand?
The A3935KLQTR supports a load supply voltage (VBAT) range of –0.6 V to 40 V. Its absolute maximum rating is 40 V, and its VBAT overvoltage protection is adjustable from 19.4 V to 40 V via the OVSET pin. Operation beyond 40 V risks permanent damage to the A3935KLQTR device.
Does the A3935KLQTR require external bootstrap diodes?
No, the A3935KLQTR integrates internal bootstrap diodes with forward voltage of 0.8–2.3 V and current limit of –1150 mA. External diodes are unnecessary; only external bootstrap capacitors (e.g., 0.47 μF) connected to CA/CB/CC pins are required for high-side gate drive.
How does the A3935KLQTR handle motor phase current sensing?
The A3935KLQTR uses an integrated differential amplifier with CSP/CSN inputs for Kelvin-connected shunt resistors. It provides a rail-to-rail CSOUT voltage proportional to phase current (gain = 19.2 V/V), with ±25 mV offset error and 1.6 MHz bandwidth-enabling precise analog current feedback for the host controller without external op-amps.
What fault conditions trigger the active-low FAULT output on the A3935KLQTR?
The FAULT pin on the A3935KLQTR asserts low for any of these conditions: VBAT overvoltage, VBAT undervoltage, VREG undervoltage, VDD undervoltage, thermal shutdown, motor lead short-to-battery, short-to-ground, or bridge-open fault. All fault responses are hardware-autonomous and do not require MCU intervention.
Is the A3935KLQTR pin-compatible with newer Allegro gate drivers like the A4964?
No, the A3935KLQTR is not pin-compatible with the A4964. The A4964 uses a 44-pin TSSOP package with different pin assignments, added SPI interface, and distinct fault reporting architecture. Migration requires PCB layout revision and firmware adaptation; the A3935KLQTR remains supported for legacy automotive designs.
A3935KLQTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Allegro MicroSystems
- Series:
- -
- Package/Case:
- 36-BSOP (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- -
- Function:
- Controller - Commutation, Direction Management
- Output Configuration:
- Pre-Driver - Half Bridge (3)
- Interface:
- Parallel
- Technology:
- Power MOSFET
- Step Resolution:
- -
- Applications:
- -
- Current - Output:
- -
- Voltage - Supply:
- 4.75V ~ 5.25V
- Voltage - Load:
- 7V ~ 40V
- Operating Temperature:
- -40°C ~ 135°C (TA)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QSOP
A3935KLQTR FAQ
1.How can I place an order for A3935KLQTR through Aetrix?
Please submit a Request for Quotation (RFQ) for A3935KLQTR 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 A3935KLQTR reliable?
The price and inventory of A3935KLQTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A3935KLQTR is usually 5 days.
3.What payment methods are accepted for A3935KLQTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A3935KLQTR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for A3935KLQTR?
A3935KLQTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your A3935KLQTR 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 A3935KLQTR?
For technical support, including A3935KLQTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A3935KLQTR requirements.
6.How does Aetrix verify that A3935KLQTR is sourced from the original manufacturer or authorized distributors?
All A3935KLQTR 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 A3935KLQTR meets industry standards.
7.What is the process for return or replacement of A3935KLQTR?
All A3935KLQTR units undergo pre-shipment inspection (PSI). If there is an issue with A3935KLQTR, 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 A3935KLQTR part is unused and in its original packaging.
Return procedure for A3935KLQTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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