Product Overview: STMicroelectronics L4964

The STMicroelectronics L4964 is a versatile, high-performance monolithic power switching regulator, specifically designed for efficient step-down (buck) voltage conversion in automotive and industrial environments. It integrates all necessary control, driver, and power elements into a single package, making it a highly integrated and compact solution for DC-DC power management.

The device delivers high efficiency, precise regulation, and robust protection features, suitable for powering microprocessors, sensors, and analog circuitry. The L4964 includes a 5 V linear regulator, PWM control, power switching transistor, oscillator, error amplifier, soft start, and current limiting—all on-chip.

Key Features

* Integrated 5 V linear regulator output
* Capable of delivering up to 4 A output current
* Operating input voltage range up to 50 V
* Internal PWM control with fixed frequency
* High efficiency switching regulator (up to ~90%)
* On-chip protection: current limiting, thermal shutdown, output short-circuit protection
* Soft start for inrush current limiting
* Synchronization capability with external clock
* Internally generated 5.1 V reference
* Housed in Multiwatt-15 or PowerSO-20 package

Electrical Specifications

* Input Voltage Range: 8 V to 50 V
* Output Voltage Range: Adjustable from 5.1 V to 40 V
* Switching Frequency: Fixed, typically 150 kHz
* Output Current: Up to 4 A continuous
* Efficiency: Up to 90% under typical conditions
* Reference Voltage: 5.1 V ±2%
* Line Regulation: 0.5% typical
* Load Regulation: 0.3% typical
* Standby Current: < 200 µA in disabled mode
* Soft Start Time: Programmable via external capacitor

Functional Blocks

* PWM Controller: Regulates duty cycle based on feedback from the output, maintaining a constant voltage regardless of input variations.
* Integrated Power Switch: NPN transistor capable of handling the main current path, eliminating the need for external switching FETs.
* Error Amplifier: Compares feedback voltage with the internal reference and controls PWM duty cycle accordingly.
* 5 V Regulator: Internal linear regulator supplies 5 V from the main input for biasing control logic and can also be used externally for other system components.
* Oscillator: Generates the internal clock for PWM timing; can be synchronized to an external clock.
* Protection Logic: Includes overcurrent, overvoltage, overtemperature, and output short-circuit protections.

Thermal and Packaging Information

* Package Options: Available in Multiwatt-15 and PowerSO-20 packages
* Junction Temperature Range: -40°C to +150°C
* Thermal Shutdown Threshold: 150°C typical
* Thermal Resistance (Junction-to-Case): ~3°C/W (Multiwatt)

Control and Monitoring Features

* Enable/Disable Pin: Provides remote shutdown capability to minimize power consumption during standby
* Synchronization Pin: Allows multiple L4964 devices or other systems to be synchronized to a common clock source
* Reset Output: Provides system reset function with adjustable delay on power-up
* Current Limiting: Pulse-by-pulse current limiting protects against overloads
* Output Voltage Adjustment: Via external resistor divider from the feedback pin

Applications

* Automotive ECU power supplies
* Industrial control systems
* Motor control units
* Battery-powered or distributed power systems
* Power supply for embedded microcontrollers
* Voltage regulators for telecommunication and instrumentation systems

Advantages

* High level of integration reduces BOM count and PCB area
* On-chip protections increase system reliability and robustness
* Wide input voltage range supports automotive cranking and industrial surges
* High efficiency reduces power loss and thermal dissipation
* Adjustable output and flexible control enable broad application usage

Conclusion

The STMicroelectronics L4964 is a powerful and highly integrated switching regulator that combines efficiency, reliability, and flexibility in a single device. With a wide input voltage tolerance, high output current capability, and embedded protection and control features, it serves as a robust solution for demanding power supply applications in automotive and industrial sectors. Its high efficiency and internal linear 5 V regulator also make it suitable for systems requiring multiple voltage rails with minimal external circuitry.