FAN6751MR Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – Highly-Integrated Green-Mode PWM Controller

September 2008
FAN6751MR
Highly-Integrated Green-Mode PWM Controller
Features
ƒ High-Voltage Startup
ƒ Low Operating Current: 4mA
ƒ Linearly Decreasing PWM Frequency to 18KHz
ƒ Fixed PWM Frequency: 65KHz
ƒ Peak-current-mode Control
ƒ Cycle-by-cycle Current Limiting
ƒ Leading-edge Blanking (LEB)
ƒ Synchronized Slope Compensation
ƒ Internal Open-loop Protection
ƒ GATE Output Maximum Voltage Clamp: 18V
ƒ VDD Under-Voltage Lockout (UVLO)
ƒ VDD Over-Voltage Protection (OVP)
ƒ Internal Recovery Circuit (OVP, OLP)
ƒ Internal Sense Short-Circuit Protection
ƒ External Constant Power Limit (Full AC Input
Range)
ƒ Internal OTP Sensor with Hysteresis
ƒ Built-in 5ms Soft-Start Function
ƒ Built-in VIN Pin Pull HIGH (> 4.7V) Recovery
Function for Second-Side Output OVP
ƒ Brownout Protection with Hysteresis
Applications
General-purpose switch-mode power supplies and
flyback power converters, including:
ƒ Power Adapters
ƒ Open-frame SMPS
Description
The highly integrated FAN6751 series of PWM
controllers provides several features to enhance the
performance of flyback converters.
To minimize standby power consumption, a proprietary
green-mode function provides off-time modulation to
linearly decrease the switching frequency at light-load
conditions. To avoid acoustic-noise problems, the
minimum PWM frequency is set above 18KHz. This
green-mode function enables the power supply to meet
international power conservation requirements. With the
internal high-voltage startup circuitry, the power loss
due to bleeding resistors is also eliminated. To further
reduce power consumption, FAN6751 is manufactured
using the BiCMOS process, which allows an operating
current of only 4mA.
Built-in synchronized slope compensation achieves
stable peak-current-mode control. The proprietary,
external line compensation ensures constant output
power limit over a wide AC input voltage range, from
90VAC to 264VAC.
FAN6751 provides many protection functions. In
addition to cycle-by-cycle current limiting, the internal
open-loop protection circuit ensures safety should an
open-loop or output short-circuit failure occur. PWM
output is disabled until VDD drops below the UVLO lower
limit, when the controller starts up again. As long as VDD
exceeds ~26V, the internal OVP circuit is triggered.
FAN6751 is available in an 8-pin SOP package.
Ordering Information
Part Number
Operating
Temperature
Range
FAN6751MRMY -40°C to +105°C
Eco Status
Package
Green
8-Lead, Small Outline
Package (SOP-8)
Packing Method
Tape & Reel
For Fairchild’s definition of “green” Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2008 Fairchild Semiconductor Corporation
FAN6751MR • Rev. 1.0.0
www.fairchildsemi.com