Overview
The L6566A is an extremely versatile peak-current-mode PWM controller specifically designed for high-performance offline flyback converters operated from front-end power factor correction (PFC) stages. It is produced by STMicroelectronics and is compliant with regulations such as EN61000-3-2 and JEITA-MITI. The device 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, among other key functionalities.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Voltage range (VHVS) | -0.3 to 700 | V |
| Startup current (IHVS) | Self-limited | |
| IC supply voltage (VCC) | Self-limited | |
| Maximum pin voltage (Vmax) | -0.3 to 7 | V |
| Zero current detector max. current (IZCD) | ±5 | mA |
| Internal oscillator frequency (fsw) | 10 to 300 | kHz |
| Maximum duty cycle (Dmax) | 70 to 75 | % |
| Thermal resistance junction to ambient (RthJA) | 120 | °C/W |
| Junction operating temperature range (TJ) | -40 to 150 | °C |
Key Features
- Selectable multi-mode operation: fixed-frequency (FF) or quasi-resonant (QR)
- Onboard 700 V high-voltage startup
- Advanced light load management
- Low quiescent current (< 3 mA)
- Adaptive UVLO
- Line feedforward for constant power capability vs. mains voltage
- Pulse-by-pulse OCP, shutdown on overload (latched or auto-restart)
- Transformer saturation detection
- Switched supply rail for PFC controller
- Latched or auto-restart 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, such as DVD players, VCRs, set-top boxes
- IT equipment, 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 voltage range for VHVS?
The maximum voltage range for VHVS is -0.3 to 700 V.
- What is the purpose of the adaptive UVLO in the L6566A?
The adaptive UVLO helps minimize issues related to fluctuations in the self-supply voltage due to transformer parasites.
- What protection functions are included in the L6566A?
The protection functions include not-latched input undervoltage (brownout), output OVP (auto-restart or latch-mode selectable), OCP with delayed shutdown, and transformer saturation detection.
- How does the L6566A manage light load conditions?
The L6566A enters a controlled burst-mode operation at very light load, which helps keep the consumption from the mains low and meet energy saving recommendations.
- What is the thermal resistance junction to ambient (RthJA) of the L6566A?
The thermal resistance junction to ambient (RthJA) is 120 °C/W.
- What is the junction operating temperature range of the L6566A?
The junction operating temperature range is -40 to 150 °C.
- What package type is the L6566A available in?
The L6566A is available in an SO16N package.
- How does the L6566A achieve zero-voltage switching (ZVS)?
ZVS can be achieved in QR operation by synchronizing MOSFET turn-on to the transformer's demagnetization.
- What is the maximum duty cycle in FF mode?
The maximum duty cycle in FF mode is limited to 70% (min.).
