APPLICATION NOTE
R01AN1087EJ0201 Rev. 2.01 Page 1 of 27
Mar. 26, 2013
RL78/I1A
LED Control Using RL78/I1A
Purpose
The purpose of this application note is to describe the control method for LED lighting systems using the
RL78/I1A microcontroller features.
Readers
This document is intended for system engineers who design and develop LED lighting systems and powe r
supply systems.
The target products are as follows:
• 20-pin: R5F1076C
• 30-pin: R5F107AE, R5F107AC
• 38-pin: R5F107DE
R01AN1087EJ0201
Rev. 2.01
Mar. 26, 2013
<R>
RL78/I1A LED Control Using RL78/I1A
R01AN1087EJ0201 Rev. 2.01 Page 2 of 27
Mar. 26, 2013
Table of Contents
1.
Introduction........................................................................................................................................ 3
2. Overview of LED Control Using RL78/I1A ........................................................................................ 4
2.1 RL78/I1A Features for LED System Control ..................................................................................... 4
2.2 System Block Diagram...................................................................................................................... 5
2.3 Pin Functions of RL78/I1A ................................................................................................................ 6
3. LED Control Software Description .................................................................................................... 7
3.1 File Configuration .............................................................................................................................. 7
3.2 Initialization of the Internal Peripheral Functions .............................................................................. 8
3.3 Constant Current and Dimming Control.......................................................................................... 10
3.4 PI Control Method ........................................................................................................................... 13
3.5 Calculation of the PI Control Formula’s Coefficients....................................................................... 16
3.6 Software Flow Charts...................................................................................................................... 19
4. Get Started Quickly with the RL78/I1A DC/DC LED Control Evaluation Board.............................. 23
APPENDIX A Pictures .......................................................................................................................... 25
APPENDIX B Schematic ...................................................................................................................... 26