L6741

The STMicroelectronics L6741 is a high-voltage half-bridge driver IC designed for controlling power MOSFETs and IGBTs in switching applications. It integrates a high-voltage gate driver with level-shifting circuitry capable of driving N-channel devices in half-bridge configurations up to 600 V. The IC is optimized for power supply applications such as AC-DC converters, motor drives, class-D audio amplifiers, and LED drivers. Its architecture supports high-speed switching, fault detection, and robust operation in noisy environments. L6741 features separate high- and low-side drivers, internal dead-time management, and advanced protection mechanisms, making it suitable for efficient and reliable power conversion systems.

## Key Features

* High-voltage half-bridge driver for N-channel MOSFETs/IGBTs
* Wide supply voltage range: VCC = 10 V to 20 V, VBS = 10 V to 20 V
* High-side floating supply operation up to 600 V
* Low-side gate drive voltage: VCC
* High-side gate drive voltage: VBS
* Internal level shifter for high-side drive
* Programmable dead-time control with adjustable delay
* Fast propagation delay: 50 ns typical
* Short-circuit protection with desaturation detection
* Under-voltage lockout (UVLO) for both high- and low-side drivers
* Thermal shutdown protection
* Low quiescent current for efficient operation
* Bootstrap capacitor support for high-side drive
* High noise immunity: 100 mV typical
* Separate inputs for high- and low-side control
* Available in 16-lead SOIC and PowerSO packages
* Operating junction temperature: -40°C to +150°C

## Electrical Characteristics

* Supply voltage, VCC: 10 V to 20 V
* Bootstrap supply voltage, VBS: 10 V to 20 V
* High-side output voltage swing: VBS - 0.7 V typical
* Low-side output voltage swing: VCC - 0.7 V typical
* High-side turn-on rise/fall time: 20 ns / 25 ns typical
* Low-side turn-on rise/fall time: 15 ns / 20 ns typical
* Propagation delay (input to output): 50 ns typical
* Input logic voltage high (VIH): 2.4 V minimum
* Input logic voltage low (VIL): 0.8 V maximum
* Maximum output source current: 2 A peak
* Maximum output sink current: 2 A peak
* UVLO threshold VCC rising: 8.8 V typical
* UVLO threshold VCC falling: 8.0 V typical
* Desaturation detection threshold: VCE(sat) ≈ 5 V typical

## Functional Architecture

* The L6741 integrates a high-voltage half-bridge gate driver with two separate channels: high-side (HO) and low-side (LO).
* High-side output is level-shifted from the floating supply VBS, referenced to the source of the high-side MOSFET or IGBT.
* Low-side output is referenced to the ground potential (VSS) and driven directly from VCC.
* Internal dead-time control prevents simultaneous conduction of high- and low-side devices, avoiding cross-conduction.
* Desaturation detection monitors the collector-emitter voltage of the high-side IGBT/MOSFET to detect short-circuit conditions.
* Under-voltage lockout (UVLO) disables gate drive when supply voltage is insufficient to fully turn on the power device.
* The IC features fast propagation and matched rise/fall times to reduce switching losses and EMI.

## Input and Output

* Inputs: INH (high-side control), INL (low-side control) compatible with TTL/CMOS logic levels
* Outputs: HO (high-side gate drive), LO (low-side gate drive) capable of sourcing and sinking peak currents up to 2 A
* Bootstrap capacitor between VB and VS enables high-side floating operation
* Input thresholds designed for robust switching in noisy environments
* Open-drain or complementary output stage ensures rapid gate charging/discharging

## Protections and Limitations

* Desaturation detection provides short-circuit protection on high-side devices
* Overtemperature protection: internal thermal shutdown at 150°C typical
* UVLO on both VCC and VBS prevents under-voltage operation
* Maximum voltage between HO and VS: 600 V absolute maximum
* Maximum voltage between VCC and VSS: 20 V absolute maximum
* External bootstrap capacitor sizing required to maintain high-side drive voltage during operation
* Careful PCB layout recommended to minimize parasitic inductance and EMI in high-speed switching circuits

## Package and Mechanical

* Package options: 16-lead SOIC, PowerSO
* Lead-free, RoHS-compliant
* Compact footprint suitable for dense power electronics boards
* Typical thermal resistance θJA: 60°C/W for SOIC, 35°C/W for PowerSO
* Sufficient creepage and clearance between high-voltage pins for 600 V operation

## Applications

* AC-DC and DC-DC power converters
* Brushless DC (BLDC) motor drives
* Synchronous rectification in power supplies
* Class-D audio amplifiers
* High-brightness LED drivers
* Solar inverters and energy storage systems
* General-purpose half-bridge and full-bridge power stages

## Advantages

* Integrated high-voltage driver reduces component count compared to discrete solutions
* Fast switching times minimize losses in MOSFETs and IGBTs
* Comprehensive protection features improve system reliability and safety
* Low quiescent current supports energy-efficient designs
* High noise immunity ensures stable operation in industrial and automotive environments
* Adjustable dead-time provides flexibility for various power devices and switching frequencies

## Summary

The STMicroelectronics L6741 is a versatile high-voltage half-bridge driver suitable for high-speed and high-reliability applications. Its combination of high-side level-shifting, low-side direct drive, integrated protections, and fast switching capability enables robust operation of N-channel MOSFETs and IGBTs in demanding power systems. The L6741 is particularly suited for AC-DC and DC-DC conversion, motor drives, and LED driving applications where precise control, safety, and efficiency are critical. Its integrated features reduce external components, simplify layout, and ensure high system performance.