lm3450主要特性:

51電子網公益庫存:

BTS5589G

C40273

LT1469CDF

K6X0808X1D-DF70

■ critical conduction mode pfc

■ over-voltage protection

■ feedback short circuit protection

■ 70:1 pwm decoded from phase dimmer

■ analog dimming

■ programmable dimming range

■ digital angle and dimmer detection

■ dynamic holding current

■ smooth dimming transitions

■ low power operation

■ start-up pre-regulator bias

■ precision voltage reference

lm3450應用:

■ dimmable downlights, troffers, and lowbays

■ indoor and outdoor area ssl

■ power supply pfc


圖1.lm3450方框圖

圖2.lm3450典型應用電路圖

圖3.lm3450典型反激電路圖

圖4.pfc系統架構圖

圖5.lm3450 pfc控制電路圖

圖6.lm3450 調光譯碼器電路圖

圖7.lm3450 調光保持路圖

圖8.lm3450初級偏壓電路圖

lm3450評估板

the lm3450 evaluation board is designed to provide an ac to led solution for a 15w led load. specifically, it takes an ac mains input and converts it to a constant current output of 350 ma for a series string of 1 to 14 leds (maximum led stack voltage of 45v). there are two assembly versions designed to operate from two different nominal ac input voltages, 120v_ac or 230v_ac.

the board employs a two stage design with an lm3450 flyback primary stage and an lm3409 secondary stage. the lm3450 provides an isolated 50v regulated output voltage and a power factor corrected input current. the lm3409 uses the 50v flyback output as its input and provides a constant current of 350 ma to the led load. this two stage design provides excellent line and load regulation as well as isolation.

the board is comprised of two copper layers with components on both sides and an fr4 dielelctric. the two stage design has several key advantages over a single stage design including:

no 120 hz led current ripple.

better dimming performance at low dimming levels.

better line disturbance rejection.

better efficiency using small led stack voltages.

lm3450評估板主要指標:

input voltage range: v_in = 180v_ac to 265v_ac

regulated flyback output voltage: v_out = 50v

maximum led stack voltage: v_led < 45v

regulated led current: i_led = 350 ma


圖9.lm3450評估板外形圖

圖10.簡化lm3450評估板電路圖

圖11.lm3450評估板偏壓電路

圖12.lm3450輸入emi濾波器電路

圖13.lm3450評估板完整電路圖
230vac 評估板材料清單(bom):

ns 公司的lm3450是具有pfc和相位調光譯碼器的led驅動器,pfc在調整輸出電壓同時保持輸入端有極好的功率因素.相位調光70:1 pwm譯碼,具有過壓和反饋短路保護,非常適合離線10-100w的led驅動,主要用在調光筒燈,平光燈和室內外區域照明以誠相待及電源pfc介紹了lm3450主要特性, 方框圖, 典型應用電路圖和反激電路圖, pfc系統架構圖和控制電路圖, 調光譯碼器電路圖以及lm3450評估板主要指標,完整電路圖和材料清單(bom).