Overview
The L6566A, produced by STMicroelectronics, is an extremely versatile current-mode primary controller IC designed for high-performance offline flyback converters. It is particularly suited for applications that require compliance with EN61000-3-2 or JEITA-MITI regulations. The IC supports both fixed-frequency (FF) and quasi-resonant (QR) operation, allowing users to select the mode based on application needs. It features an externally programmable oscillator, advanced light load management, and a non-dissipative high-voltage startup circuit. The L6566A is also equipped with various protection functions, including overcurrent protection, overvoltage protection, and brownout protection, making it a robust solution for power supply designs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Voltage range (referred to ground) | -0.3 to 700 | V |
| IC supply voltage (Icc = 20 mA) | 10.6 to 23 | V |
| Turn-on threshold | 13 to 15 | V |
| Turn-off threshold | 9.4 to 10.6 | V |
| Quiescent current | < 3 mA | mA |
| Maximum duty cycle (FF mode) | 70% min. | % |
| Gate-driver current | -600/+800 mA | mA |
| Storage temperature | -55 to 150 | °C |
| Junction operating temperature range | -40 to 150 | °C |
| Thermal resistance junction to ambient | 120 | °C/W |
Key Features
- Selectable multi-mode operation: fixed frequency or quasi-resonant
- Onboard 700 V high-voltage startup circuit
- Advanced light load management
- Low quiescent current (< 3 mA)
- Adaptive undervoltage lockout (UVLO)
- Line feedforward for constant power capability vs. mains voltage
- Pulse-by-pulse overcurrent protection (OCP) with shutdown on overload (latched or auto-restart)
- Transformer saturation detection
- Switched supply rail for PFC controller
- Latched or auto-restart overvoltage protection (OVP)
- Brownout protection
- -600/+800 mA totem pole gate-driver with active pull-down during UVLO
- SO16N package
Applications
- Notebook, TV, and LCD monitor adapters
- High power chargers
- PDP/LCD TVs
- Consumer appliances (e.g., DVD players, VCRs, set-top boxes)
- IT equipment and games
- Auxiliary power supplies
- Power supplies in excess of 150 W
Q & A
- What are the operating modes of the L6566A?
The L6566A supports both fixed-frequency (FF) and quasi-resonant (QR) operation.
- What is the maximum duty cycle in fixed-frequency mode?
The maximum duty cycle in FF mode is limited to 70% minimum.
- How does the L6566A manage light load conditions?
The IC enters a controlled burst-mode operation at very light loads to keep consumption from the mains low and meet energy saving recommendations.
- What protection functions are included in the L6566A?
The device includes overcurrent protection, overvoltage protection, brownout protection, and transformer saturation detection.
- How does the adaptive UVLO function work?
The adaptive UVLO helps minimize issues related to fluctuations in the self-supply voltage due to transformer parasites.
- What is the purpose of the line feedforward function?
The line feedforward function compensates for the rise in power capability with the input voltage.
- How does the L6566A handle overvoltage conditions?
The IC has latched or auto-restart overvoltage protection (OVP) that can be selected externally.
- What is the role of the soft-start current source?
The soft-start current source allows for a gradual increase in duty cycle during startup, improving noise immunity and preventing overload conditions.
- What package type is the L6566A available in?
The L6566A is available in an SO16N package.
- What are some typical applications of the L6566A?
Typical applications include notebook adapters, high power chargers, PDP/LCD TVs, and consumer appliances.
