Fairchild 公司的FAN6754B是高度集成的绿色模式PWM控制器,能提高反激转换器的性能,最小化待机功耗.高压起动,低工作电流1.5mA,固定PWM频率65kHz,频率跳频以降低EMI,峰值电流模式控制,主要用在LCD监视器,LCD TV和笔记本电脑.本文介绍了FAN6754B主要特性,功能方框图,典型应用电路图以及65W(19V / 3.42A)反激转换器的主要指标,电路图,材料厂清单和PCB布局图.
FAN6754B: Highly Integrated Green- Mode PWM Controller
The highly integrated FAN6754B 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 continuously decrease the switching frequency under light-load conditions.
Under zero-load and very light-load conditions, FAN6754B saves PWM pulses by entering deep burst mode. This burst mode function enables the power supply to meet international power conservation requirements.
FAN6754B integrates a frequency-hopping function internally to reduce EMI emission of a power supply with minimum line filters. Built-in synchronized slope compensation is accomplished by proprietary HV monitor to adjust VLimit for constant output power limit over universal AC input range. The gate output is clamped at 13V to protect the external MOSFET from over-voltage damage.
Other protection functions include AC input brownout protection with hysteresis, and VDD over-voltage protection. For over-temperature protection, an external NTC thermistor can be applied to sense the external switcher’s temperature. When VDD OVP or OTP are activated, an internal latch circuit is used to latch-off the controller. The latch mode is reset when the VDD supply is removed.
FAN6754B is available in an 8-pin SOP package.

FAN6754B主要特性:
 High-Voltage Startup
 AC Input Brownout Protection with Hysteresis
 Monitor HV to Adjust VLimit
 Low Operating Current: 1.5mA
 Linearly Decreasing PWM Frequency to 22KHz
 Frequency Hopping to Reduce EMI Emission
 Fixed PWM Frequency: 65KHz
 Peak-Current-Mode Control
 Cycle-by-Cycle Current Limiting
 Leading-Edge Blanking (LEB)
 Internal Open-Loop Protection
 GATE Output Maximum Voltage Clamp: 13V
 VDD Under-Voltage Lockout (UVLO)
 VDD Over-Voltage Protection (OVP)
 Programmable Over-Temperature Protection (OTP)
 Internal Latch Circuit (OVP, OTP)
 Open-Loop Protection (OLP); Restart for MR, Latch for ML
 Built-in 8ms Soft-Start Function

FAN6754B应用:
LCD Monitor
LCD TV
Notebook PC

图1.FAN6754B功能方框图

图2.FAN6754B典型应用电路图

用于笔记本电脑适配器的低成本绿色模式PWM控制器反激转换器65W(19V / 3.42A) This document describes a 65W power supply using FAN6754AMR and FAN6204MY synchronous rectification IC. This power supply is targeted towards power adapters and open-frame consumer products.
With the internal high-voltage startup circuitry, the power loss due to bleeding resistors is eliminated. To further reduce power consumption, FAN6754AMR is manufactured using the BiCMOS process. This allows an operating current of only 1.5mA and low startup current of 30μA. Built-in synchronized slope compensation ensures the stability of peakcurrent-mode control. In addition, FAN6204MY improves conduction losses in heavy load, and the SR controller stops all SR switching operation to reduce the operating current in light load.

反激转换器主要指标:


图3.65W反激转换器外形图

图4.65W反激转换器电报挂号路图
65W反激转换器材料清单(BOM):



图5.65W反激转换器PCB布局图(顶层)

图6.65W反激转换器PCB布局图(层)