Intelligent lighting platform solution

This paper mainly introduces the secomtel based on Renesas (Renesas) electronic building intelligent lighting platform for high performance 78K0/Ix2 series MCU development for lighting applications personal solutions, the scheme satisfies the high-end lighting products intelligent dimming control and networking needs in hardware and software, with high performance and low cost the advantage of.

Status quo of the lighting technology with the rapid development of the lighting industry, the lighting control scheme is more and more, the design of power supply and the lamp driving circuit, safety protection and management interface are more flexible. At present, lighting techniques mainly include fluorescent lamps, LED lamps and HID mainstream technology, the wide application of the power driven topology difference is very large, the other structure extends from the common Flyback, Buck, and Boost are widely used in product design, whether to adopt advanced digital design of energy saving control, whether the application of flyback and Buck support topology and Boost flexible, development cycle and launch time will determine the success or failure of the product, but the traditional lighting scheme is often used for devices to implement, difficult to meet the needs of rapid development.

Therefore, an excellent lighting platform solution will undoubtedly need to support the topology of flexible application, DALI, DMX512, 0-10V and meet, wireless, infrared and other mainstream lighting control dimming and networking requirements, in view of this situation, secomtel developed by Renesas electronics 78K0/Ix2 (Renesas) series MCU as the core platform of intelligent lighting solutions, with reference to design rich, lighting design in hardware and software development for various lighting manufacturers to provide effective guidance and help manufacturers more efficient development of lighting system has own intellectual property rights.

Two, 78K0/Ix2 series MCU introduction

78K0/Ix2 series MCU (Renesas) for Renesas electronic lighting applications carefully designed high performance 8 bit MCU, as shown in Figure 1, the series MCU is located in the lighting market to meet current high resolution dimming control, abnormal protection, intelligent control and other popular demand, depending on the implementation of green energy-efficient lighting system the cost and performance of single MCU.

Figure 1-78K0/Ix2 MCU series design philosophy

The 78K0/Ix2 series MCU has a wealth of hardware resources, providing excellent hardware support for flexible lighting power supply design and dimming control. Specific performance in:

1.16 bit PWM maximum count timer clock frequency 40MHz output, and a comparator linked PFC control system, with 2 dead time control PWM output, suitable for driving half bridge / full bridge circuit to realize frequency control;

2 built-in amplifier, comparator A/D and 10bit multi-channel high-speed analog circuits, simplify the external circuit;

3 timer trigger A/D sampling, signal capture useful right;

4 comparator / external interrupt to realize hardware disables the output function, rapid response, to ensure the safety of;

5 timer remote control interface and UART function, application oriented infrared and wireless remote control, DALI bus communication module port, suitable for intelligent lighting control;

More than 6 protection modules: window type watchdog, clock control, low voltage alarm, reliable operation.

Three, the world strong intelligent lighting platform program

Intelligent lighting platform secomtel development solutions the main functions of 78K0/Ix2 series MCU hardware resources based on the rich core, aims to design lighting products with high performance and low cost, provide the reference for the design of a variety of flexibility for customers in the LED lighting, fluorescent lamps, HID lighting and other fields.

Figure 2 is the LED driver reference scheme to control the application, in this scheme, only by using the comparator, the output of the PWM interlock function, can independent 3 channel constant current control; by changing the internal reference voltage or PWM output can achieve dimming setting; and MCU and DALI DMX512, supports a variety of sensors, analog input etc. many communication interfaces can be selected according to the external environment of communication control scheme suitable for optimal control.

Figure 2-78K0/Ix2 LED drive control

Following Flyback circuit for example process constant current control through the comparator

Figure 3-Flyback constant current control circuit

For switching power supply, PWM duty cycle determines the output voltage, as shown in Figure 3, the circuit starts to work, the current LED after sampling to MCU built-in comparator port, compare and reference value, generate an interrupt signal to adjust the duty ratio of PWM, the change process is shown in Figure 4, such as when the current is greater than the reference value, reduce the duty cycle; on the contrary, the duty cycle is increased and eventually reached a steady state dynamic load current.

For dimming, 78K0/Ix2 series MCU have a variety of ways, by changing the comparator reference voltage or by timer TMH1 and PWM output interlock function, in addition, secomtel scheme can also use the MCU powerful data processing ability, through the algorithm control function of ADC and embedded to realize constant current control at the same time, to provide sufficient resources for the expansion of MCU function.

Figure 5-DALI from system structure

Adopts BOOST power supply topology, input voltage after voltage direct drive LED lamps; load current sampling, by embedding algorithm to realize constant current control; MCU built-in DALI communication interface, connected through the DALI bus and the host, and the host to achieve mutual communication, complete the operation control command from the upper PC; temperature and light lamps illumination