Research And Design Of High Precision And Adjustable Current-limited Power Distribution Chip

With the rapid development of portable electronic products,such as mobile phones and tablet computers,as well as the urgent need for green energy technology,power management system gradually tends to be integrated,modular and intelligent.As one of the power management chips,the current-limited power distribution chip is an important part to achieve pluralism power control.As a kind of power control chip,the current-limited power distribution chip has a high requirement on the current-limited precision and chip efficiency.Due to the low current detection accuracy,the current-limited threshold drift is usually more than 15%.In this paper,by analyzing the traditional architecture,combined with the project requirements,a high-precision adjustable current-limited power distribution chip is designed.The chip generates high voltage by charge pump to drive N type power MOS for high efficiency.A high precision current detection circuit is designed with high speed gain-bootstrap structure and temperature compensation technology.A high voltage EA is designed to constitute current-limited loop with soft start function.And the bandgap is designed with chop offset correction to decrease voltage drift.The current-limited threshold can be adjusted by outside res and select by ILIM_SEL,which is convenient for the processor to control the power supply mode.In addition,the chip also has a complete over temperature protection,under voltage lockout,over-current protection and abnormal state display function.The chip is designed with 0.25 ?m BCD process.The limiting current drift caused by temperature and load change is only 8.7%.And limiting current can be changed from 150 mA to 2.5 A by outside res.The Ron is only 61.5 m? when output current is 2 A of which the efficiency is 97.1%.Reference voltage drift only ±7.5 mV benefit from chop technology.The chip has two over temperature threshold 135? at current-limited mode and 155? at non current-limited mode.When power voltage below 4.05 V,chip gets in under voltage lockout,until power voltage exceeds 4.15 V.Over-current time is 1.6 ?s.