Fairchild FAN6751MR Data Handbook

FA 6751M ighly-Integrated G reen-M ode PW ontroller

September 2008

FAN6751MR Highly-Integrated Green-Mode PWM Controller Features Description

High-Voltage Startup The highly integrated FAN6751 series of PWM controllers provides several features to enhance the

Low Operating Current: 4m A

performance of flyback converters.

Linearly Decreasing PWM Frequency to 18KHz

To minimize standby power consumption, a proprietary Fixed PWM Frequency: 65KHz green-mode function provides off-time modulation to linearly decrease the switching frequency at light-load

Peak-current-mode Control

conditions. To avoid acoustic-noise problems, the minimum PWM frequency is set above 18KHz. This

Cycle-by-cycle Current Limiting

green-mode function enables the power supply to meet

Leading-edge Blanking (LEB) international power conservation requirements. With the

internal high-voltage startup circuitry, the power loss

Synchronized Slope Compensation

due to bleeding resistors is also eliminated. To further

Internal Open-loop Protection reduce power consumption, FAN6751 is manufactured

using the Bi CMOS process, which allows an operating

GATE Output Maximum Voltage Clamp: 18V

current of only 4m A.

VDD Under-Voltage Lockout (UVLO)

Built-in synchronized slope compensation achieves

VDD Over-Voltage Protection (OVP) stable peak-current-mode control. The proprietary,

external line compensation ensures constant output

Internal Recovery Circuit (OVP, OLP)

power limit over a wide AC input voltage range, from

Internal Sense Short-Circuit Protection 90VAC to 264VAC. External Constant Power Limit (Full AC Input FAN6751 provides many protection functions. In Range) addition to cycle-by-cycle current limiting, the internal

open-loop protection circuit ensures safety should an

Internal OTP Sensor with Hysteresis

open-loop or output short-circuit failure occur. PWM

Built-in 5ms Soft-Start Function output is disabled until VDD drops below the UVLO lower

limit, when the controller starts up again. As long as VDD

Built-in VIN Pin Pull HIGH (> 4.7V) Recovery

exceeds ~26V, the internal OVP circuit is triggered.

Function for Second-Side Output OVP

FAN6751 is available in an 8-pin SOP package.

Brownout Protection with Hysteresis

Applications General-purpose switch-mode power supplies and flyback power converters, including: Power Adapters Open-frame SMPS

Ordering Information

Operating

Part Number Temperature Eco Status Package Packing Method

Range

FAN6751MRMY -40°C to +105°C Green 8-Lead, Small Outline

Package (SOP-8) 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 www.fairchildsemi.com FAN6751MR • Rev. 1.0.0