Texas Instruments LM3448 -120VAC, 6W Isolated Flyback LED Driver Eval Board LM3448-120VFLBK/NOPB LM3448-120VFLBK/NOPB 数据表
产品代码
LM3448-120VFLBK/NOPB
Application Report
SNOA554C – October 2011 – Revised May 2013
AN-2090 LM3448 -120VAC, 6W Isolated Flyback LED
Driver
.....................................................................................................................................................
ABSTRACT
This application note describes the performance of a LM3448 based Flyback LED driver solution that can
be used to power a single LED string consisting of seven to eleven series connected LEDs from a 85 V
be used to power a single LED string consisting of seven to eleven series connected LEDs from a 85 V
RMS
to 135 V
RMS
, 60 Hz input power supply.
Contents
1
Introduction
..................................................................................................................
2
Key Features
................................................................................................................
3
Applications
..................................................................................................................
4
Performance Specifications
................................................................................................
5
Typical Performance Characteristics
.....................................................................................
6
EMI Performance
...........................................................................................................
7
Circuit Operation With Forward Phase TRIAC Dimmer
................................................................
8
Circuit Operation With Reverse Phase TRIAC Dimmer
...............................................................
9
Thermal Performance
......................................................................................................
10
LM3448 Device Pin-Out
..................................................................................................
11
Demo Board Wiring Overview
...........................................................................................
12
Demo Board Assembly
...................................................................................................
13
Design Guide
...............................................................................................................
13.1
DCM Flyback Converter
.........................................................................................
13.2
Transformer
.......................................................................................................
13.3
Bias Supplies and Capacitances
...............................................................................
13.4
COFF Current Source
...........................................................................................
13.5
TRIAC Holding Circuit
...........................................................................................
13.6
Overvoltage Protection
..........................................................................................
13.7
Input Filter
.........................................................................................................
13.8
Inrush Limiting and Damping
...................................................................................
14
Design Calculations
.......................................................................................................
14.1
Specifications
.....................................................................................................
14.2
Preliminary Calculations
.........................................................................................
14.3
SW FET
............................................................................................................
14.4
Current Sense
.....................................................................................................
14.5
Recirculating Diode
...............................................................................................
14.6
Transformer
.......................................................................................................
14.7
COFF Current Source
...........................................................................................
14.8
PassFET
...........................................................................................................
14.9
Input Capacitance
................................................................................................
14.10
Output Capacitance
..............................................................................................
14.11
Overvoltage Protection Zener Diode
..........................................................................
14.12
Transil Clamp
.....................................................................................................
15
Evaluation Board Schematic
.............................................................................................
16
Transformer Design
.......................................................................................................
17
PCB Layout
.................................................................................................................
All trademarks are the property of their respective owners.
1
SNOA554C – October 2011 – Revised May 2013
AN-2090 LM3448 -120VAC, 6W Isolated Flyback LED Driver
Copyright © 2011–2013, Texas Instruments Incorporated