Flyback LED power supply controller solution with PFC

LED power controller is one of the key components in LED lighting applications. Marvell's 88EM8080/81 device is a high-performance flyback LED power controller with power factor correction (PFC). This article introduces the new generation of lighting power technology in combination with advanced solid-state (SS) lighting device solutions. The focus is on the performance, characteristics and application advantages of single-stage PFC flyback converter. With the rapid development of LED lighting application products in China, the controller chip of the upstream product of the LED industry chain will definitely receive more and more attention.

Topology

Marvell's 88EM8080/81 device is a solution designed with unique digital signal processor (DSP) technology. Compared with the complex two-stage AC/DC power converter, the flyback PFC (isolated buck/boost) topology technology is an isolated PFC conversion stage that simplifies the circuit technology. In LED lighting applications, single-stage isolated PFC conversion is more cost-effective than two-stage. Figure 1 is a schematic diagram comparing the traditional two-stage power converter with the single-stage solution.

The chip adopts average current mode control (ACMC) for the control algorithm of PFC application, so it has low harmonic distortion and strong noise suppression. The chip has a fixed operating frequency, which is 60KHz (88EM8080) and 120KHz (88EM8081) according to different models.

Features

The flyback LED power supply controller with PFC has the following features:

unique DSP control strategy

Continuous current mode (CCM) or discontinuous current mode (DCM) operation

Adaptive loop control to obtain high power factor and low harmonic distortion under wide range of input voltage and low load conditions

Minimum number of peripheral components

Undervoltage lockout (UVLO)

Overvoltage protection (OVP)

Overtemperature protection (OTP)

Output high-precision constant current control

Advantages:

Single-stage AC/DC converter solid-state (SS) lighting architecture is shown in Figure 2.

Figure 2 Schematic diagram of single-stage AC/DC converter solid-state lighting architecture

The advantages of this solid-state lighting controller can be described as follows:

1. Single-stage PFC

Single-stage isolated PFC conversion simplifies system design and reduces costs compared to the two-stage structure, so it is cost-effective. The chip adopts average current mode control (ACMC) for the control algorithm of PFC application, which brings the benefits of low harmonic distortion and enhanced noise suppression. The 8-pin SOIC package further saves the space of the circuit board.

2. Digital signal processing (DSP) technology

The device adopts digital signal processing technology, so it has digital intelligence, high reliability, and can quickly add new features according to needs.

3. Adaptive loop control

The use of adaptive loop control in PFC is still a pioneering work, benefiting from modern digital control technology. Due to the use of adaptive feedback loop control, high power factor and low harmonic distortion THD can be obtained under a wide range of input voltage and low load conditions. The principle of the feedback loop is to allow the power control system to detect and adjust the output current and track the reference LED current that meets the design requirements. It also detects and adjusts the primary input current signal and tracks the sinusoidal current reference value to achieve power factor correction. Marvell's dedicated adaptive loop control can achieve high power factor under high input voltage and low load conditions. The efficiency is as high as 85-88%. The chip also provides sufficient switching device driving capability, so that high-frequency LED power supply systems can achieve higher conversion efficiency.

Applications

The flyback LED power supply controller with PFC can provide users with the smallest size, lowest system cost, smallest harmonic distortion THD and best power factor PF for LED lighting applications. The 88EM8080/81 based on the flyback topology is suitable for high-performance, low-cost, LED lighting systems with PFC. As a power supply controller, this device can be used for flyback converter solutions with PFC in various commercial or household applications, which is undoubtedly an ideal choice for solid-state LED lighting and green energy needs.