Design Of A Main/Sub Dual-channel LED Driver

Safety is the most important factor in miner production, there are a lot of accidents are caused by miner’s lamp. Traditional miner’s lamps use lead-acid batteries for power, incandescent tungsten as light source which has a number of disadvantages such as large volume, high maintenance costs, short lifetime, great power consumption and unsafely because of the fragile glass. This paper designed a lithium battery as the power supply, the LED as light source of high precision under voltage threshold and automatic switching dual channel driver with constant current, not only overcome the above disadvantages, but also promote the standardization production, the drive circuit of miner’s lamp lighting also meet industry standards.This paper presents a structure that the dual channel can switch automatically by detecting the battery voltage with high precision under voltage threshold to ensure working time of the main light production and emergency time of auxiliary lights. Accurate detection of changes in battery capacity guarantees that the right charging time and improves the safety of the lamp. To charge battery consistently, design a sequential logic circuit, make under voltage threshold voltage in the range of±2%with80mV hysteresis for high precision requirement. In order to reduce the power dissipation, design a8000-fold high-gain current amplifier to drive linear MOS with0.1V dropout for200mA.The chip provides the main LED shorts protection and over temperature protection against unexpected situations.The chip adopts Taiwan nuvoton0.6um CDMOS process, the SOP8package. Layout design makes full use of matching and kelvin contact technology. Test parameters of30random ICs in the27℃and85℃, provide the range of parameters for qualified ICs by using six sigma analysis methods which is the judgment for the large quantities of chip test.