Overview
LED power controllers are one of the key components in LED lighting applications. Marvell's 88EM8080/81 device is a flyback high performance LED power controller with power factor correction (PFC). This article introduces a new generation of lighting power technology in combination with advanced solid state (SS) lighting device solutions. Focus on the performance, features and application advantages of single-stage PFC flyback converters. With the rapid development of LED lighting application products in China, the upstream product controller chip of the LED industry chain will surely receive more and more attention.
Topology
Marvell's 88EM8080/81 devices are designed with unique digital signal processor (DSP) technology. The flyback PFC (Isolated Buck/Boost) topology is an isolated PFC conversion stage that simplifies circuit technology compared to complex two-stage AC/DC power converters. In LED lighting applications, single-stage isolated PFC conversion is better than two-stage cost performance. Figure 1 is a schematic diagram of a conventional two-stage power converter compared to a single-stage solution.
Figure 1 Comparison of a traditional two-stage power converter with a single-stage solution
The chip's control algorithm for PFC applications uses average current mode control (ACMC), which has low harmonic distortion and strong noise suppression. The chip has a fixed operating frequency of 60 KHz (88EM8080) and 120KHz (88EM8081) depending on the model.
Characteristics
The flyback LED power controller with PFC has the following features:
·Unique DSP control strategy
Continuous current mode (CCM) or discontinuous current mode (DCM) operation
Adaptive loop control for high power factor and low harmonic distortion over a wide range of input voltages and low load conditions
·The minimum number of peripheral components
· Undervoltage lockout (UVLO)
·Overvoltage protection (OVP)
· Overheat protection (OTP)
· Output high precision constant current control
advantage:
The single-stage AC/DC converter solid-state (SS) lighting architecture is shown in Figure 2.
Figure 2 Schematic diagram of solid-state lighting system for single-stage AC/DC converter
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