基于NCL30000設(shè)計(jì)的中小型開關(guān)電源

NCL30000是中小型開關(guān)電源控制器，適用于單級PFC LED驅(qū)動(dòng)器。NCL30000具有非常低24uA的起動(dòng)電流，工作電流僅2mA，能逐個(gè)周期進(jìn)行電流保護(hù)，可提供500mA電流源，主要用在LED驅(qū)動(dòng)電源，商業(yè)和住宅區(qū)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(yīng)用框圖和簡化反激應(yīng)用框圖，以及NCL30000LED2GEVB評估板電路圖和材料清單（BOM）。
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, transconductance 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

CyclebyCycle 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 PbFree, Halogen Free/BFR Free and are RoHS Compliant

NCL30000典型應(yīng)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(yīng)用框圖

圖3。簡化反激應(yīng)用框圖：次級恒流控制