Product overview
Description
The L6566B is an extremely versatile current-mode primary controller ICs, specifically designed for high-performance offline flyback converters. It is also suited for single-stage single-switch input-current-shaping converters (single-stage PFC) for applications supposed to comply with EN61000-3-2 or JEITA-MITI regulations.
Both fixed-frequency (FF) and quasi-resonant (QR) operation are supported. The user can pick either of the two depending on application needs. The device features an externally programmable oscillator: it defines converters switching frequency in FF mode and the maximum allowed switching frequency in QR mode.
When FF operation is selected, the ICs work like a standard current-mode controller with a maximum duty cycle limited at 70 % min. The oscillator frequency can be modulated to mitigate EMI emissions.
QR operation, when selected, occurs at heavy load and is achieved through a transformer demagnetization sensing input that triggers MOSFETs turn-on. Under some conditions, ZVS (zero-voltage switching) can be achieved. Converters power capability rise with the mains voltage is compensated by line voltage feedforward. At medium and light load, as the QR operating frequency equals the oscillator frequency, a function (valley skipping) is activated to prevent further frequency rise and keep the operation as close to ZVS as possible.
With either FF or QR operation, at very light load the ICs enter a controlled burst-mode operation that, along with the built-in non-dissipative high-voltage start-up circuit and the low quiescent current, helps keep low the consumption from the mains and meet energy saving recommendations.
An innovative adaptive UVLO helps minimize the issues related to the fluctuations of the self-supply voltage due to transformers parasites.
The protection functions included in this device are: not-latched input undervoltage (brownout), output OVP (auto-restart or latch-mode selectable), a first-level OCP with delayed shutdown to protect the system during overload or short circuit conditions (autorestart or latch-mode selectable) and a second-level OCP that is invoked when the transformer saturates or the secondary diode fails short. A latched disable input allows easy implementation of OTP with an external NTC, while an internal thermal shutdown prevents IC overheating.
Programmable soft-start, leading-edge blanking on the current sense input for greater noise immunity, slope compensation (in FF mode only), and a shutdown function for externally controlled burst-mode operation or remote ON/OFF control complete the equipment of this device.
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All features
- Latched or autorestart OVP
- Programmable frequency modulation for EMI reduction
- -600/+800 mA totem pole gate driver with active pull-down during UVLO
- Brownout protection
- SO16N package
- Pulse-by-pulse OCP, shutdown on overload (latched or autorestart)
- Line feedforward for constant power capability vs. mains voltage
- Selectable multi-mode operation: fixed frequency or quasi-resonant
- Advanced light load management
- On-board 700 V high-voltage start-up
- Adaptive UVLO
- Transformer saturation detection
- Low quiescent current (< 3 mA)
Circuit Diagram
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STMicroelectronics - L6566B
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Quality and Reliability
| Part Number | Marketing Status | Package | Grade | RoHS Compliance Grade | Material Declaration** |
|---|---|---|---|---|---|
| L6566B | Active | SO-16 | Industrial | Ecopack2 | |
| L6566BTR | Active | SO-16 | Industrial | Ecopack2 |
(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.
Sample & Buy
| Part Number | Marketing Status | Budgetary Price (US$)*/Qty | Order from ST | Order from distributors | Package | Packing Type | RoHS | Country of Origin | ECCN (US) | ECCN (EU) | Operating Temperature (°C) (min) | Operating Temperature (°C) (max) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| L6566B | | | distributors No availability of distributors reported, please contact our sales office | ||||||||||
| L6566BTR | | | distributors No availability of distributors reported, please contact our sales office |
L6566B Active
L6566BTR Active
(*) Suggested Resale Price (USD) per defined quantity for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office or our Distributors