LED area lighting power supply based on NCL30001

Some area lighting applications require an isolated, regulated output voltage with input power factor correction. These applications typically use a two-stage power conversion architecture, where a boost power factor correction (PFC) converts and pre-regulates the AC input line voltage to 400 V DC, which is then fed to a conventional DC-DC (DC-DC) converter of any suitable topology (typically a flyback converter for applications up to 150 W).

We can use a simpler approach to improve this traditional two-stage conversion architecture into a single-stage architecture that integrates power factor correction and the main converter (i.e., DC-DC converter). This single-stage architecture provides significant application advantages because it does not require the use of large-sized boost inductors, high-voltage MOSFETs, power rectifiers, and large capacitors. Of course, this single-stage architecture will bring some performance trade-offs in certain aspects, but it is an energy-efficient and cost-effective solution suitable for applications with relatively constant loads, such as LED area lighting.

The NCL30001 is a single-stage controller that integrates power factor correction and isolated step-down DC-DC conversion circuits to help reduce component count, reduce system costs, and support higher overall energy efficiency of LED power supplies. The NCL30001 provides a constant current to directly drive the LED, eliminating the need for linear or DC-DC conversion integrated in the LED light bar (Figure 1). ON Semiconductor's design note AND8427 describes an LED power supply based on the NCL30001 single-stage continuous current mode (CCM) PFC controller and the NCS1002 secondary-side constant voltage constant current (CVCC) controller, which is suitable for area lighting applications such as street lights.

Figure 1: The NCL30001-based LED driver solution is suitable for 40 to 125 W area lighting applications.

Tests show that under 90 to 264 Vac input voltage conditions, the NCL30001-based LED power supply provides high efficiency of more than 85%, a power factor of more than 0.9, and provides short-circuit and overvoltage protection. Designers can adjust the regulated current and regulated voltage by slightly adjusting the resistance in the secondary control circuit to support the specific application requirements of the end product. It is also worth mentioning that although this power supply is designed to provide a fixed current with tight current regulation, it can also work in constant voltage mode because its current and voltage are regulated according to the tightly regulated 2.5 V reference voltage integrated in the NCS1002.