The Design Of LED Performance Testing Platform

The light-emitting diodes due to its energy-saving, safety, low cost of maintenance, show great promise in the lighting engineering. Lighting devices is considered to become main lighting device in the near future. The project is to develop a multi-data fusion measuring instruments which can detect the voltage, drive current, light intensity; the light fades parameters of the LED lights. It can be used to solve the verification and measurement of LED life, switching characteristics.This design use C8051f120microcontroller as control unit, use320240LCD for display. Design switching voltage source for driving LEDs which has3.3V,5V,±12V multi-channel output. Use a switching power supply chip TOP245YN to meet power demand. The output voltages of the bi-directional control,12regulation of DA, Digital Potentiometer DS3502furnish high precision. Use chip the AMC7140as the core component of the feedback loop NC to design constant current source. The output current of the constant current source is0-400mA.Measure the relative intensity of light of the LED by the light intensity sensor. Use the EEPROM to save the set parameters and data collected when the system power down. Control the system to perform a variety of measurements via the keyboard and the host computer.The data processing is more complex, due to its large amount of data collected. The space of storing the data is large. This design is to achieve communication between the microcontroller and the computer, processing, displaying and storing the data on the host computer. The MCU will capture analog signal through the on-chip A/D converted into digital signals, then use the serial communication sent to the host computer to process. Using the MAX3232chip as the data transfer, TTL level translates into RS232level, using full-duplex asynchronous communication. Because some of the computers have no serial port, so use the USB to RS232serial converter line.The design of program the host computer use LabVIEW to write. Icons, connection and block diagram is instead of the traditional program code. Read the serial data protocol by VISA. Process the data through an agreement between PC and MCU. At the same time, the host computer through the VISA protocol to write data to the serial port and command, control MCU for a variety of measurements.