Overview
The L6591TR, produced by STMicroelectronics, is a double-ended PWM controller specifically designed for soft-switched half bridge topology. This IC provides complementary PWM control, where the high-side switch is driven ON for a duty cycle D and the low-side switch for a duty cycle 1-D, with D < 50%. It features an externally programmable deadtime to ensure soft-switching and support high-frequency operation up to 500 kHz. The L6591TR also includes advanced light load management, adaptive undervoltage lockout (UVLO), and various protection mechanisms such as pulse-by-pulse overcurrent protection (OCP) and transformer saturation detection.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Frequency | Up to 500 kHz | |
| Maximum Duty Cycle | 46% to 50% | % |
| IC Supply Voltage (Vcc) | 11.3 to 22 V | V |
| Turn-on Threshold (VccOn) | 13 to 15 V | V |
| Turn-off Threshold (VccOff) | 9.2 to 11.3 V | V |
| High-Voltage Startup Generator | 60 to 90 V | V |
| Gate Drive Peak Current (IHVG, ILVG) | 0.3 A min. source, 0.8 A min. sink | A |
| Junction Temperature Operating Range | -40 to 150 °C | °C |
| Package | SO16N |
Key Features
- Complementary PWM control for soft-switched half bridge with programmable deadtime
- Advanced light load management with controlled burst mode operation
- Adaptive undervoltage lockout (UVLO) and pulse-by-pulse overcurrent protection (OCP)
- Transformer saturation detection and latched disable input for easy implementation of OTP or OVP
- Programmable soft-start and digital leading-edge blanking on the current sense input pin
- High-voltage startup circuit and synchronous bootstrap diode for high-side gate drive
- Interface with PFC controller for two-stage power-factor-corrected systems
Applications
- High power AC-DC adapters and chargers
- Desktop PCs and entry-level servers
- Telecom SMPS (Switch-Mode Power Supplies)
- Power-factor-corrected systems
Q & A
- What is the primary function of the L6591TR?
The L6591TR is a double-ended PWM controller designed for soft-switched half bridge topology, providing complementary PWM control.
- What is the maximum operating frequency of the L6591TR?
The L6591TR can operate up to 500 kHz.
- What protection mechanisms are included in the L6591TR?
The IC includes pulse-by-pulse OCP, transformer saturation detection, and latched disable input for OTP or OVP implementation.
- How does the L6591TR manage light loads?
The L6591TR enters a controlled burst mode operation at very light loads to keep consumption low and comply with energy-saving regulations.
- What is the purpose of the high-voltage startup generator in the L6591TR?
The high-voltage startup generator charges the capacitor connected to the Vcc pin until it reaches the startup threshold, ensuring proper startup of the IC.
- Can the L6591TR be used in power-factor-corrected systems?
Yes, the L6591TR has an interface with the PFC controller to enable the pre-regulator to be switched off between bursts, aiding in energy-saving compliance.
- What is the package type of the L6591TR?
The L6591TR is available in the SO16N package.
- What is the junction temperature operating range of the L6591TR?
The junction temperature operating range is -40 to 150 °C.
- How does the adaptive UVLO in the L6591TR work?
The adaptive UVLO minimizes issues related to fluctuations of the self-supply voltage with the output load, adapting to the loading conditions of the converter.
- What is the purpose of the soft-start feature in the L6591TR?
The soft-start feature generates a voltage ramp using an internal 20 µA generator, ensuring a gradual startup of the system.
