L6566
Product Page
L6566 is a new, extremely versatile current-mode primary
controller IC specifically designed for high-performance offline
flyback converters. Both Fixed-Frequency (FF) and Quasi-Resonant
(QR) operation are supported by the same product; the user can pick
either depending on the application requirements.
L6566 is a multi-die product, including a high voltage section (HV
start-up) in BCD off-line technology and a low voltage section (the
core of the controller) in BCD6 technology, mounted together in
a small, standard SO-16N plastic package. |
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The device features an externally programmable oscillator which
defines the converter’s switching frequency in FF mode and
the maximum allowed switching frequency in QR mode. When FF operation
is selected, the IC works like a standard current-mode controller
(UC384x-like) with a maximum duty cycle limited at 70 % min. QR
operation, when selected, occurs at heavy load and is achieved through
a transformer demagnetization sensing input that triggers the Power
MOSFET’s turn-on.
With a very small load, in FF or QR operation the IC enters controlled
burst-mode operation that, along with the built-in non-dissipative
high-voltage start-up circuit and a reduced quiescent current, helps
keep the consumption from the mains low while meeting the most demanding
energy saving regulations.
L6566 is supplied in two orderable versions, L6566A and L6566B.
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L6566A is specifically designed
for offline flyback converters operating from a front-end
Power Factor Corrector. The L6566A provides an interface with
the PFC controller that turns-off the pre-regulator at light
load. |
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L6566B is designed for offline flyback
converters where a front-end PFC is not expected. L6566B has
a frequency modulation input that modulates the oscillator
frequency. This modulation is used to reduce the peak value
of EMI emissions. |
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Main Features And
Benefits |
Selectable multi-mode operation
On-board high-voltage start-up
Low quiescent current (< 3 mA)
Adaptive UVLO
Line feed-forward
Pulse-by-pulse OCP
Transformer saturation detection
Latched or autorestart OVP
Brown-out protection
Component count minimization
Fits all world-wide energy regulations
System block diagram
Hi-end AC-DC adapter / charger
LCD/CRT monitor, LCD / CRT TV
Digital consumer
Single-stage PFC |
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