用户手册 — Texas Instruments LM3448 -120VAC, 6W Isolated Flyback LED Driver Eval Board LM3448-120VFLBK/NOPB

目录

• Introduction

  3
• Key Features

  3
• Applications

  3
• Performance Specifications

  3
• Demo Board

  4
• LED Current vs. Line Voltage (using TRIAC Dimmer)

  4
• Typical Performance Characteristics

  5
• Efficiency vs. Line Voltage

  5
• Power Factor vs. Line Voltage

  5
• LED Current vs. Line Voltage

  5
• Output Power vs. Line Voltage

  5
• SW FET Drain Voltage Waveform (VIN = 120VRMS, 9 LEDs, ILED = 228mA)

  5
• FLTR2 Waveform (VIN = 120VRMS, 9 LEDs, ILED = 228mA)

  5
• EMI Performance

  6
• LINE – CISPR/FCC Class B Peak Scan

  6
• NEUTRAL – CISPR/FCC Class B Peak Scan

  6
• LINE – CISPR/FCC Class B Average Scan

  6
• NEUTRAL – CISPR/FCC Class B Average Scan

  6
• EN-61000-3 Class C Limits

  6
• Circuit Operation With Forward Phase TRIAC Dimmer

  7
• Forward phase circuit at full brightness

  7
• Forward phase circuit at 90° firing angle

  7
• Forward phase circuit at 150° firing angle

  7
• Circuit Operation With Reverse Phase TRIAC Dimmer

  8
• Reverse phase circuit at full brightness

  8
• Reverse phase circuit at 90° firing angle

  8
• Reverse phase circuit at 150° firing angle

  8
• Thermal Performance

  9
• Top Side - Thermal Scan

  9
• Bottom Side - Thermal Scan

  10
• LM3448 Device Pin-Out

  11
• Device Pin-Out

  11
• Pin Description 16 Pin Narrow SOIC

  11
• Demo Board Wiring Overview

  12
• Demo Board Assembly

  12
• Wiring Connection Diagram

  12
• Top View

  12
• Test Points

  12
• Bottom View

  13
• Design Guide

  14
• Evaluation Board Schematic

  14
• 13.1 DCM Flyback Converter

  15
• Direct Line-Injection Circuit

  15
• FLTR2 Waveform with No Dimmer

  15
• Typical Operation of FLTR2 Pin

  16
• DCM Flyback Current Waveforms

  17
• 13.2 Transformer

  18
• Switch Node Ringing

  20
• TVS Diode Clamp

  20
• 13.3 Bias Supplies and Capacitances

  21
• Bias Supply Circuits

  21
• Auxiliary Winding Bias Circuit

  21
• 13.4 COFF Current Source

  23
• COFF Current Source Circuit

  23
• 13.5 TRIAC Holding Circuit

  24
• 13.6 Overvoltage Protection

  24
• TRIAC Holding Circuit

  24
• OVP Circuit

  24
• 13.7 Input Filter

  25
• Input EMI Filter

  25
• 13.8 Inrush Limiting and Damping

  26
• Inrush Current Spike

  26
• Design Calculations

  27
• 14.1 Specifications

  27
• 14.2 Preliminary Calculations

  27
• 14.3 SW FET

  28
• 14.4 Current Sense

  28
• 14.5 Recirculating Diode

  29
• 14.6 Transformer

  29
• 14.7 COFF Current Source

  30
• 14.8 PassFET

  30
• 14.9 Input Capacitance

  30
• 14.10 Output Capacitance

  31
• 14.11 Overvoltage Protection Zener Diode

  31
• 14.12 Transil Clamp

  31
• Evaluation Board Schematic

  32
• Evaluation Board Schematic

  32
• Bill of Materials

  33
• Transformer Design

  35
• PCB Layout

  36
• Top Layer

  36
• Bottom Layer

  36