APPLICATION NOTE
R01AN0674EJ0100 Rev.1.00 Page 1 of 33
2011.05.31
78K0/Ix2 Microcontrollers
78K0/Ix2 Microcontrollers
LED Lighting System with PFC Control
Readers The target readers of this document are us er engineers who design an d develop LED li ghting systems and
power supply systems.
The target products are as follows:
•78K0/IB2:
μ
PD78F0745, 78F0746, 78F0755, 78F0756
•78K0/IA2:
μ
PD78F0743, 78F0744, 78F0753, 78F0754
•78K0/IY2:
μ
PD78F0740, 78F0741, 78F0742, 78F0750, 78F0751, 78F0752
Purpose The purpose of this document is to describe the features and the control methods for the LED lighting
system with PFC control using the 78K0/Ix2 microcontroller.
Caution The sample programs are for reference only. We do not guarantee their operation. Before using the
sample programs, evaluate them thoroughly on the user's s et.
CONTENTS
CHAPTER 1 OVERVIEW....................................................................................................................2
1.1 Introduction................................................................................................................................2
1.2 Features of LED Lighting System Control with 78K0/Ix2...........................................................3
1.3 System Block Diagram ..............................................................................................................4
1.4 Pin Functions of 78K0/Ix2..........................................................................................................5
1.5 System Operation Overview......................................................................................................6
CHAPTER 2 CONTROL METHODS FOR VARIOUS FUNCTIONS...................................................7
2.1 LED Control...............................................................................................................................7
2.1.1 LED control overview ..........................................................................................................7
2.1.2 LED control software design ...............................................................................................9
2.1.3 Calculating coefficients of PI control formula ......................................................................13
2.2 PFC Control...............................................................................................................................16
2.2.1 PFC control overview..........................................................................................................16
2.2.2 PFC control software design...............................................................................................19
APPENDIX A EZ-0011 EXTERNAL APPEARANCE .........................................................................25
APPENDIX B EZ-0011 CIRCUIT DIAGRAM......................................................................................26
APPENDIX C EZ-0011 PARTS LIST .................................................................................................27
R01AN0674EJ0100
Rev.1.00
2011.05.31
78K0/Ix2 Microcontrollers 78K0/Ix2 Microcontrollers
LED Lighting System with PFC Control
R01AN0674EJ0100 Rev.1.00 Page 2 of 33
2011.05.31
CHAPTER 1 OVERVIEW
1.1 Introduction
Lighting accounts for about 16% of domestic household power
consumption (Figure 1-1). The use of LED's in lighting has been
increasingly popular in recent years due to the reduction of CO
2
emissions
and the needs for energy saving. This is because LED lighting has higher
luminance efficiency and a longer life than the conventional incandescent
bulbs or fluorescent lights. For energy saving in systems, there are greater
needs for optimal ON/OFF control and dimming control for lighting using
communication and sensors, and lighting system control with
microcontrollers is required. On the other hand, there are greater needs
for low costs for promoting LED lighting. There have been many cases
in which board platforms are used to reduce development man-hours or the functions of analog control IC's are
built into a microcontroller.
With these needs, this application note describes the features, system configuration, and control methods of
LED lighting system with the 78K0/Ix2 microcontroller by using the LED lighting evaluation board with PFC control
EZ-0011 (Photo 1-1) as an example. To purchase the EZ-0011, contact Renesas Electronics sales office or
distributor.
Photo 1-1. External Appearance of EZ-0011
Figure 1-1. Percentage of
Lighting Equipment in Domestic
H
ousehold
P
ower
Consumption
Lighting
equipment
Approx. 16%