SG6742ML Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – Highly Integrated Green-Mode PWM Controller

June 2009
SG6742ML/MR
Highly Integrated Green-Mode PWM Controller
Features
ƒ High-Voltage Startup
ƒ Low Operating Current: 2.7mA
ƒ Linearly Decreasing PWM Frequency to 22KHz
ƒ Frequency Hopping to Reduce EMI Emission
ƒ Fixed PWM Frequency: 65KHz
ƒ Peak-Current-Mode Control
ƒ Cycle-by-Cycle Current Limiting
ƒ Leading-Edge Blanking
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 Programmable Over-Temperature Protection (OTP)
ƒ Internal Latch Circuit (OVP, OTP)
ƒ Internal Sense Short-Circuit Protection
ƒ Build-in 5ms Soft-Start Function
ƒ Constant Power Limit (Full AC Input Range)
ƒ Internal OTP Sensor 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 SG6742ML/MR PWM controller
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 22KHz. The
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, SG6742ML/MR is
manufactured using the BiCMOS process, which allows
an operating current of only 2.7mA.
SG6742ML/MR integrates a frequency-hopping function
that helps reduce EMI emission of a power supply with
minimum line filters. Its built-in synchronized slope
compensation achieves stable peak-current-mode
control. The proprietary, internal line compensation
ensures constant output power limit over a wide AC
input voltage range, from 90VAC to 264VAC.
SG6742ML/MR 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.
SG6742ML/MR is available in an 8-pin SOP package.
Ordering Information
Part
Number
SG6742MLSY
SG6742MRSY
Operating
Temperature
Range
-40 to +105°C
-40 to +105°C
OLP
Function
Package
Latch 8-Lead Small Outline Package (SOP)
Restart 8-Lead Small Outline Package (SOP)
Eco
Status
Green
Green
Packing
Method
Tape & Reel
Tape & Reel
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2008 Fairchild Semiconductor Corporation
SG6742ML/MR • Rev. 1.0.4
www.fairchildsemi.com