Fremont Micro Devices FT821x Preliminary
www.fremontmicro.com Page 1 of 6 DS821x –A3
Transition-mode PFC Controller
FEATURES
DESCRIPTION
¾ Transition - mode control of PFC pre-regulator
¾ Low input current THD
¾ Ultra-low (≤50μA) start up current
¾ Low (≤3.5 mA) quiescent current
¾ Precise internal reference voltage
¾ Zero-current switching
¾ Leading edge blanking instead of RC filtering
¾ Clamp gate output voltage
¾ Adjustable line compensation
¾ Adjustable Output Overvoltage Protection
¾ Vcc Over Voltage Protection
¾ Open control loop protection
¾ IC Over Temperature Protection(OTP)
¾ Disable function
¾ Dip-8/SOP-8 packages
APPLICATIONS
¾ IEC61000-3-2 compliant SMPS ( TV, desktop
PC, monitor) up to 150W
¾ Hi-end AC-DC adapter/charger
¾ Entry level server & web server
The FT821x is a current-mode PFC controller
operating in Transition Mode (TM). The FT821x has
rich protections. It provides a controlled on-time to
regulate the output DC voltage and achieve natural
power factor correction.
The highly linear multiplier makes the device capable
of working in wide input voltage range applications
(from 85V to 265V) with an excellent THD.
The output voltage is controlled by means of a
voltage-mode error amplifier and a precise internal
voltage reference.
The device features extremely low consumption and
includes a disable function suitable for IC remote
ON/OFF control, which makes it easier to comply
with energy saving norms.
An effective two-step OVP enables to safely handle
overvoltages either occurring at start-up or resulting
from load disconnection.
The totem-pole output stage is capable of driving a
MOSFET or IGBT with source and sink currents of
± 400mA typically. The device is operating in
transition mode and it is optimized for Electronic
Lamp Ballast application, AC-DC adapters and
SMPS.
