Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design

Fairchild’s FSQ500L is a low-cost product designed to replace linear power supplies. The chip integrates the current mode PWM of SenseFET, and the built-in PWM controller mainly has the following features: built-in oscillator, under-voltage lockout protection, overload protection, built-in leading edge blanking circuit, optimized gate drive on/off, hysteresis thermal shutdown protection and temperature compensated precision current sources. This article mainly introduces the main features and device block diagram of FSQ500L, and introduces a 2.04W output power supply development scheme based on FSQ500L chip. It mainly introduces the main features, performance, schematic diagram, PCB diagram and device list of the scheme.

The FSQ500L is specially designed for a replacement of linear power supplies with low cost. This device combines current-mode Pulse Width Modulator (PWM) with a senseFET. The integrated PWM controller features include: a fixed oscillator, Under Voltage Lockout (UVLO) protection , Overload Protection (OLP), Leading-Edge Blanking (LEB), an optimized gate turn-on/turn-off driver, Thermal Shutdown (TSD) protection with hysteresis, and temperature-compensated precision-current sources for loop compensation. When compared to a linear power supply, the FSQ500L device reduces total size and weight, while increasing efficiency, productivity, and system reliability. This device provides a basic platform for cost-effective flyback converters.

FSQ500L main features:

Single Chip 700V SenseFET Power Switch

Precision Fixed Operating Frequency: 130kHz

No-load consumption 250mW at 265VAC with Burst Mode and Down to 60mW with External Bias

Internal Startup Switch

Soft-Start Time Tuned by External Capacitor

Under-Voltage Lockout (UVLO) with Hysteresis

Pulse-by-Pulse Current Limit

Overload Protection (OLP) and Internal Thermal Shutdown Function (TSD) with Hysteresis

Auto-Restart Mode

No Need for Auxiliary Bias Winding

FSQ500L application:

· DVD

· STB

· Video Game Console

· Consumer Applicance

Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design
Figure 1. FSQ500L Internal Block Diagram

FEBFSQ500L_H257v1 main features:

Single-Chip700V SenseFET Power Switch

Precious Fixed Operation Frequency: 130kHz

No-load consumption 250mW at 256VAC with Burst Mode and Down to 60mW with External Bias

Internal startup Swith

Soft-Start Time Tuned by External Capacitor

Under-Voltage Lockout with Hysteresis

Pulse-by-Pulse Current limit

Overload Protection and Internal Thermal Shutdown Function with Hysteresis

Auto-Restart Mode

No Need for Auxiliary Bias Winding

FEBFSQ500L_H257v1 circuit diagram:

Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design
Figure 2. FEBFSQ500L_H257v1 circuit diagram

FEBFSQ500L_H257v1 Bill of Materials:
Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design

PCB component layout:

Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design

Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design

Fairchild FSQ500L 5.1V/400mA compact power saving mode flyback design

The Links:   ESM4016 KCS057QV1AJ-G32 PM150RSE120