L6566BH Просмотр технического описания (PDF) - STMicroelectronics

Номер в каталоге

Компоненты Описание

производитель

L6566BH

Multimode controller for SMPS

STMicroelectronics 

Description

1

Description

L6566BH

The L6566BH is an extremely versatile current-mode primary controller IC, specifically

designed for high-performance offline flyback converters running off rectified 3-phase input

lines. It is also suited to single-stage, single-switch, input-current-shaping converters

(single-stage PFC) for applications that must comply with EN61000-3-2 or JEITA-MITI

regulations.

Both fixed-frequency (FF) and quasi-resonant (QR) operation are supported. The user can

choose either of the two depending on application needs. The device features an externally

programmable oscillator: it defines the converter switching frequency in FF mode and the

maximum allowed switching frequency in QR mode.

When FF operation is selected, the ICs work as a standard current-mode controller with a

maximum duty cycle limited to 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 MOSFET turn-on. Under some conditions, ZVS

(zero-voltage switching) can be achieved. The converter’s 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 startup circuit and the

low quiescent current, helps keep the consumption from the mains low and meet energy

saving recommendations.

An innovative adaptive UVLO helps minimize the issues related to the fluctuations of the

self-supply voltage due to transformer 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 (auto-

restart or latch-mode selectable), and a second-level OCP that is invoked when the

transformer saturates or there is a short-circuit of the secondary diode. A latched disable

input allows easy implementation of OTP with an external NTC, while an internal 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 features of this

device.

6/51

Doc ID 16610 Rev 2

Share Link: