fairchild 公司的fsq510是用于谷底開關轉換器,具有低emi和高效率, 內部集成了700v的ldmos功率開關,內置的軟起動時間為5ms,主要用在lcd tv, lcd監視器,pc和白色家電的輔助電源.本文介紹fsq510主要特性,方框圖,典型應用電路以及采用fsq510的rd-267 4.2w電源參考設計的電路和所用變壓器的主要特性和電路.

fsq510, fsq510h, and fsq510m:green mode fairchild power switch (fps™) for valley switching converter  low emi and high efficiency

a valley switching converter (vsc) generally shows lower emi and higher power conversion efficiency than a conventional hard-switched converter with a fixed switching frequency. the fsq510 (h or m) is an integrated valley switching pulse width modulation (vspwm) controller and sensefet specifically designed for offline switch-mode power supplies (smps) for valley switching with minimal external components. the vs-pwm controller includes an integrated oscillator, under-voltage lockout (uvlo), leading-edge blanking (leb), optimized gate driver, internal soft-start, temperature-compensated precise current sources for loop compensation, and self-protection circuitry.

compared with discrete mosfet and pwm controller solutions, the fsq510 (h or m) can reduce total cost, component count, size and weight; while simultaneously increasing efficiency, productivity, and system reliability.

this device provides a platform for cost-effective designs of a valley switching flyback converters.

fsq510主要特性:

uses an ldmos integrated power switch

optimized for valley switching converter (vsc)

low emi through variable frequency control and inherent frequency modulation

high efficiency through minimum drain voltage switching

extended valley switching for wide load ranges

small frequency variation for wide load ranges

advanced burst-mode operation for low standby power consumption

pulse-by-pulse current limit

protection functions: overload protection (olp), internal thermal shutdown (tsd) with hysteresis

under-voltage lockout (uvlo) with hysteresis

internal startup circuit

internal high-voltage sensefet: 700v

built-in soft-start: 5ms

fsq510應用:

auxiliary power supplies for lcd tv, lcd monitor, personal computer, and white goods


圖1.fsq510內部方框圖

圖2.fsq510典型應用電路圖

參考設計 rd-267:采用fsq510的4.2w設計
指標:


圖3. 參考設計 rd-267電路圖

圖4. 參考設計rd-267的變壓器電路圖