基于NCL30000設計的中小型開關電源

NCL30000是On Semi 公司的中小型開關電源控制器，適用于單級PFC LED驅動器。NCL30000具有非常低24uA的起動電流，工作電流僅2mA，能逐個周期進行電流保護，可提供500mA電流源，主要用在LED驅動電源，商業和住宅區LED裝飾照明，PFC恒壓電源。本文介紹NCL30000主要特性，方框圖，簡化應用框圖和簡化反激應用框圖，以及NCL30000LED2GEVB評估板電路圖和材料清單（BOM）。

NCL30000 pdf:http://www.nxhydt.com/soft/39/2010/2010041373298.html?

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 24 uA 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典型應用：

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


圖1。NCL30000方框圖

圖2。簡化NCL30000應用框圖

圖3。簡化反激應用框圖：次級恒流控制

圖4 寬輸入4-15 個LED 350mA應用電路圖

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.

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.


圖5。NCL30000LED2GEVB評估板外形圖

圖6。NCL30000LED2GEVB評估板電路圖

NCL30000LED2GEVB評估板材料清單（BOM）：