78K0/Ix2 Microcontrollers 78K0/Ix2 Microcontrollers LED Lighting System with PFC Control

2021-02-09

Readers: The target readers of this document are user engineers who design and develop LED lighting 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:μPD78F0740, 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.
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 CO2 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.
The LED lighting system with the 78K0/Ix2 microcontroller has the following features:
● Allows LED constant current/dimming control of up to 6 channels with the timer output function of the 16-bit timers X0, X1, 00 and 8-bit timer H1. This eliminates the need for an IC for LED constant current control, reducing the cost of the set.
● Allows power factor correction (PFC) control with the timer restart function that works with the comparator of the 16-bit timer X0. This eliminates the need for an IC for PFC control, reducing the cost of the set.
● Realizes the protective function that causes emergency stop of PWM output immediately (without the CPU) in case of a detection of overcurrent or overvoltage in the LED or PFC control part by using the high impedance output function that works with the comparator of the 16-bit timers X0 and X1. This eliminates the need for a dedicated protective circuit with an external comparator, reducing the cost of the set. Furthermore, operation after the emergency stop can be controlled by software, realizing a flexible protective function according to the system.
● Realizes transmission and reception of Manchester codes (transmission: 11 bits, reception: 19 bits) in compliance with the DALI communication standard with built-in hardware by using the DALI communication slave function of the serial interface UART6/DALI. This can reduce CPU load during data transmission and reception.
● The reception pin RxD6 of the serial interface UART6/DALI can be connected to the external interrupt pin INTP0 and the capture input pin TI000 of the 16-bit timer 00 inside the microcontroller. This realizes stand-by mode cancellation during the break period reception (low level for 88 μs to 1 s) of DMX512 communication as well as pulse width measurement during the break period.
● Realizes pulse width measurement during infrared remote control signal reception Note with hardware by using the pulse width measurement function of the 16-bit timer 00. This can reduce CPU load during data reception.
● Flexibly realizes time management and control during sensor detection Note with software processing of the microcontroller.

Renesas

78K0/Ix2

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Microcontrollers

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Application note & Design Guide

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English Chinese Chinese and English Japanese

2011.05.31

Rev.1.00

R01AN0674EJ0100

1.5 MB

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