FAN6747 Datasheet, PDF (1/15 Pages) Fairchild Semiconductor – Highly Integrated Green-Mode PWM Controller

January 2010
FAN6747
Highly Integrated Green-Mode PWM Controller
Features
ƒ High-Voltage JFET Startup
ƒ AC-Line Brownout Protection by HV Pin
ƒ Constant Output Power Limit by HV Pin
(Full AC-Line Range)
ƒ Two-Level Over-Current Protection (OCP) with
220ms Delay
ƒ Short-Circuit Protection (SCP) with 15ms Delay as
Output Short
ƒ Peak-Current Mode Operation with Cycle-by-Cycle
Current Limiting
ƒ Low Startup Current: 30µA
ƒ Low Operating Current: 1.7mA
ƒ Over-Temperature Protection (OTP) with an
External Negative-Temperature-Coefficient (NTC)
Thermistor
ƒ PWM Frequency Decreasing at Green-Mode
ƒ VDD Over-Voltage Protection (OVP)
ƒ Internal Latch Circuit for OVP, OTP, SCP, and OCP
Applications
General-purpose switch-mode power supplies and
flyback power converters, including:
ƒ Power Adapters
ƒ SMPS with Peak-Current Output, such as for
Printers, Scanners, Motor Drivers
ƒ AC/DC NB Adapters
ƒ Open-Frame SMPS
Ordering Information
Description
The highly integrated FAN6747 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 decrease the switching
frequency with load condition.
Under zero-load condition, the power supply enters
burst mode and burst frequency can be low to save
more power. Green-mode function enables the power
supply to meet international power conservation
requirements.
The FAN6747 is especially designed for SMPS with
peak-current output. It incorporates a cycle-by-cycle
current limiting and two-level Over-Current-Protection
(OCP) that can handle peak load with a delay time.
Once the current is over the threshold level, it triggers
the first counter 15ms and checks if VDD is below 10V; if
it is, the PWM latches off for SCP. If VDD is higher than
10V; it keeps counting to 220ms, then the PWM latches
off for OCP.
FAN6747 also integrates a frequency-hopping function
internally to help reduce EMI emission of a power
supply with minimum line filters. Built-in proprietary
internal synchronized slope compensation achieves
constant output power limit over universal AC line
range. The gate output is clamped at 14V to protect the
external MOSFET from over-voltage damage.
Other protection functions include AC-line brownout
protection with hysteresis and VDD over-voltage
protection. For over-temperature protection, an external
NTC thermistor can be applied to sense the ambient
temperature. When OCP, OVP, SCP, or OTP is
activated, an internal latch circuit latches off the
controller. The latch is reset when the VDD supply is
removed.
Part
Operating
Eco
Number Temperature Range _Status
Package
Packing
Method
FAN6747LMY
-40 to +105°C
Green
8-Lead, Small-Outline Integrated Circuit (SOIC),
JEDEC MS-012, .15-Inch Narrow Body
Tape & Reel
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
© 2009 Fairchild Semiconductor Corporation
FAN6747 • Rev. 1.0.1
www.fairchildsemi.com