Ti (NS) LM3448 TRIAC dimming offline LED drive solution

Key words: LED driver, LM3448, TI, TRIAC Ti (NS) LM3448 is an off-line LED driver integrated with a 600V MOC phase dimming. The application voltage ranges from 85VAC to 265VAC, adjustable switching frequency, no 120 Hz flicker, can provide high power LEDs Constant current, mainly for improved TRIAC dimming, solid state lighting, industrial and commercial lighting, and residential lighting. This article describes the main characteristics, simplified block diagrams, basic TRIAC dimming circuits, a typical LED driver application circuit, and a variety of design cases and indicators and materials used, LM3448 A19 EDISON modified evaluation board circuit diagrams and materials list. LM3448: Phase Dimmable Offline LED Driver with Integrated Fet The LM3448 is an adapTIve constant off-TIme AC / DC buck (step-down) constant current LED regulator designed to be compatible with TRIAC dimmers. The LM3448 provides a constant current for illuminating high power LEDs and includes a phase angle dim decoder. The dim decoder allows wide range LED dimming using standard forward and reverse phase TRIAC dimmers. The integrated high-voltage and low Rdson MOSFET reduces design complexity while improving LED driverm factor LED drivers suitable for integrated LED lamps with very low external component count. The LM3448 also provides the flexibility required to implement both isolated and non-isolated solutions based on the Flyback, Buck or Buck-Boost topology using either active or passive power factor correction (Valley- Fill) circuits. Additional features include thermal shutdown, current limit and VCC under --Voltage Lockout. Main features of LM3448: ■ Input Phase Angle Dim Decoder Circuit for LED Dimming ■ Integrated, Vertical 600V MOSFET with Superior Avalanche Energy Capability ■ Application Voltage Range 85VAC - 265VAC ■ Adjustable Switching Frequency ■ Adaptive Programmable Off-Time Allows for Constant Ripple CURRENT ■ No 120 Hz Flicker Possible ■ Low Quiescent Current ■ Thermal shutdown ■ Low Profile 16-Pin Narrow Soyi Package ■ Wave Solder Capable LM3448 Application: ■ Retrofit Triac Dimming ■ SOLID State Lighting ■ Industrial and Commercial Lighting, INDUSTRIAL LIGHTING ■ Residential Lighting 2011-10-11 13:53:29 Upload Download attachment (22.33 kB) figure 1. LM3448 simplified block diagram 2011-10-11 13:53:29 Upload Download attachment (6.38 kB) figure 2. Basic TRIAC dimming circuit 2011-10-11 13:53:29 Upload Download attachment (10.26 kB) image 3. LM3448 AC line detection circuit 2011-10-11 13:53:29 Upload Download attachment (60.06 kB) Figure 4. LM3448 typical non-isolated buck converter with Valley-Fill PFC 2011-10-11 13:53:29 Upload Download Attachment (21.6 KB) Figure 5. LM3448 Typical LED Driver Application Circuit 2011-10-11 13:53:29 Upload Download Attachment (45.64 KB)