TIDUCL3
February 2017
1
Overview
2
Resources
3
Features
4
Applications
5
Design Images
6
System Overview
6.1
System Description
6.2
Key System Specifications
6.3
Block Diagram
6.4
Highlighted Products
6.4.1
LMT87-Q1
6.4.2
TLC555-Q1
6.4.3
OPA2377-Q1
6.4.4
TL431-Q1
6.4.5
TPS92691-Q1
7
System Design Theory
7.1
PCB and Form Factor
7.2
Optimizing Board Performance Based on LED String Voltage and Current
7.3
Switching Frequency
7.4
Output Overvoltage Protection (OVP)
7.5
Current Monitoring (IMON)
7.6
Thermal Foldback
7.6.1
Changing Thermal Foldback Response
7.6.1.1
Changing Starting Point for Thermal Foldback
7.6.1.2
Changing Slope of Thermal Foldback
7.6.1.3
Constant Current at High Temperatures
7.6.2
Thermal Foldback Without PWM Dimming
7.7
Clock Generation (PWM)
7.8
Onboard Supply and Setting Duty Cycle
7.9
Buffering, Averaging, and Filtering
7.10
Boost Converter
8
Getting Started Hardware
8.1
Hardware
8.2
LED Selection
8.3
J3, LED+, LED– (Boost)
8.4
J1, POS(+), NEG(–)
8.5
J4, Temperature Sensor Connection
8.6
Duty Cycle Adjust
9
Testing and Results
9.1
Duty Cycle Accuracy
9.2
Thermal Foldback Testing
9.3
EMI Testing
9.4
Accuracy Calculation
10
Design Files
10.1
Schematics
10.2
Bill of Materials
10.3
PCB Layout Recommendations
10.3.1
Layout Prints
10.4
Altium Project
10.5
Gerber Files
10.6
Assembly Drawings
11
Related Documentation
11.1
Trademarks
12
About the Author
10.3
PCB Layout Recommendations