On Semi NCL30000 PFC LED驱动调光方案
On Semi 公司的NCL30000 是开关电源(SMPS)控制器,用于中小功率单级功率因素修正(PFC) LED驱动器.器件工作在临界导通模式(CrM),适合于反激和降压拓扑,主要用在LED驱动电源,商用和住宅区LED照明,TRIAC可调光的LED PAR灯,PFC恒压电源.本文介绍NCL30000主要特性, 方框图, 次级恒流控制的反激应用电路, 4−15个LED 350 mA 负载应用电路以及NCL30000LED2GEVB评估板电路图和材料清单.
The NCL30000 is a switch mode power supply controller intended for low to medium power single stage power factor (PF) corrected LED Drivers. The device is designed to operate in critical conduction mode (CrM) and is suitable for flyback as well as buck topologies.
Constant on time CrM operation is particularly suited for isolated flyback LED applications as the control scheme is straightforward and very high efficiency can be achieved even at low power levels. These are important in LED lighting to comply with regulatory requirements and meet overall system luminous efficacy requirements. In CrM, the switching frequency will vary with line and load and switching losses are low as recovery losses in the output rectifier are negligible since the current goes to zero prior to reactivating the main MOSFET switch.
..
