Design of White Light LED Driver IC Based on Charge Pump
|School||Hebei University of Science and Technology|
|Course||Circuits and Systems|
|Keywords||Charge pump Bias source Band-gap reference voltage source Error Amplifier Layout design|
White LED driver chips play an important role in protect white LED devices to work stability,with the extensive use of white LED devices,white LED driver chips will have broad prospect for development. Current white LED driver chips rely mainly on imports, so design and development with independent intellectual property rights of white LED driver IC has important practical significance.This topic has designed a charge pump-based white LED driver chips,using CSMC 0.6μm standard process to complete the whole circuit layout and generate a GDSII file for process manufacturers to tape. The core circuit module of the driver chip includes charge pump circuit module , multi-voltage bias circuit,reference source,error amplifier,under-voltage protection and over temperature protection module.Charge pump circuit module is the key to the design of white LED driver chip.In this paper,based on the technology of 1 or 1.5 times self-adaptive charge pump boost,using special substrate connection,which enables the design parameters and performance of chip has been greatly improved.The simulation results shows that the charge pump output ripple less than 10mV,with a greater stability than existing white LED driver chips.The reference voltage value generated by reference source also has a very strong stability, from -55℃to 125℃,the output voltage variation is±1.5mV, temperature coefficient is 6.87 ppm/℃. The turn-off threshold voltage of under-voltage protection module is 2.35V, which can turn off the chip in a low voltage to prevent over-discharge power,in order to protect the power supply.Because there is large size chip switching devices,set the over-temperature protection module thermal shutdown threshold voltage at 150℃,it can turn off the ship when the temperature is too high.The chip design uses adaptive charge pump structure with Special substrate Connection,makes boost conversion to input voltage.Through adaptive adjustment to ensure six parallel white LED device input current constant,so that each LED device keeps the same brightness.The chip is mainly used in portable electronic products,the input voltage range is 2.7~4.5V.The chip’s operating frequency is 1MHz,the working temperature range is -40 ~ +85℃.Shutdown current can be as low as 1μA under chips completely shut-down mode.The entire circuit diagram and chip layout are completed in CADENCE which is widely used in the industrial sector,and each sub-modules and overall layout of the circuit are optimized. Through the design rule checking (DRC),schematics and layout horses right (LVS) verification and other verification tools to ensure the accuracy and reliability of the layout.