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.

The device features a programmable on time limiter, zero current detect sense block, gate driver, trans−conductance error amplifier as well as all PWM control circuitry and protection functions required to implement a CrM switch mode power supply. Moreover, for high efficiency, the device features low startup current enabling fast, low loss charging of the VCC capacitor. The current sense protection threshold has been set at 500 mV to minimize power dissipation in the external sense resistor. To support the environmental operation range of Solid State Lighting, the device is specified across a wide junction temperature range of −40 C to 125 C.

NCL30000主要特性:

Very Low 24uA Typical Startup Current

Constant On Time PWM Control

Cycle−by−Cycle Current Protection

Low Current Sense Threshold of 500 mV

Low 2 mA Typical Operating Current

Source 500 mA / Sink 800 mA Totem Pole Gate Driver

Reference Design for TRIAC and Trailing Edge Line Dimmers

Wide Operating Temperature Range

No Input Voltage Sensing Requirement

Enable Function and Overvoltage Protection

These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant

NCL30000典型应用:

LED Driver Power Supplies

LED Based Down Lights

Commercial and Residential LED Fixtures

TRIAC Dimmable LED Based PAR Lamps

Power Factor Corrected Constant Voltage Supplies

图1.NCL30000方框图

图2.次级恒流控制的简化反激应用电路.

图3.宽输入4−15 LED 350 mA 负载应用电路

NCL30000LED2GEVB评估板

NCL30000LED2GEVB:15W 350mA 220/240Vac Triac Dimmer

This is a single stage power factor corrected TRIAC dimmable isolated flyback LED driver intended for lighting applications such as down lights, PAR lamps and residential/commercial LED fixtures. The NCL30000 is based on a fixed on-time, critical conduction mode (CrM) flyback topology. The board is designed to provide 350 mA of constant current and drive up to 15 W of LEDs in a single string. Closed loop regulation of the LED current is achieved which results in accurate current regulation across a range of LEDs. This board is specifically designed to support an input line voltage range of 180-265 Vac.


图4.NCL30000LED2GEVB评估板外形图

The design is power factor corrected with a nominal PF of >0.96. Triac dimming is preconfigured to drive 12 white LEDs at 350 mA from 230 Vac. For optimal dimming performance, a single capacitor can be adjusted to match other numbers of LEDs. The board can support from 4-15 LEDs in series.

图5.NCL30000LED2GEVB评估板电路图

NCL30000LED2GEVB评估板材料清单(B)M):