Design Of Boost DC-DC Converter Applied To White LED Driver

A boost DC–DC converter was designed for the application of white LED. The method of Current mode Pulse width module was adopted for decreasing the ripple of output voltage and the Technology of synchronous was used for increasing the circuit efficiency. Fixed 1MHz operation frequency of this converter allows the use of small, low ESR capacitors as well as a more integration, which is more important in portable application.In the paper, the background was introduced at first, the opportunity and challenge for Chinese power management design was illuminated. Then the detail circuits of design were depicted clearly, including Error amplifier, Bandgap, the driver of Power device, oscillator, PWM comparator, over-voltage protector, thermal shutdown and the block for soft-star.The process of SANYO 1.6um 1 poly 2 metal BiCMOS was used for design. Every circuits pass the functional and performance simulation, and the results of simulation meet the specification. The key specification of this system is: input voltage is range from 2.7V to 7V; the typical switching current is 400mA, the max output voltage is 14.6V, and the efficiency of converter is up to 80%.The design can be used widely in mobile phone,MP3 and other fields which need the white LED for backlight.