The reference design is a high efficiency (>94%) isolated AC/DC single string output LED lighting solution for high watt (>100W) general LED lighting.
The topology uses Transition Mode (TM) PFC plus LLC control, which can support PWM dimming and analog dimming on the output side. The target application for this reference design is TV LED backlight, outdoor and high-bay general LED lighting.
CT is eliminated in the design and the PSR controller UCC28700 is used for aux power in order to reduce overall cost.
This reference design includes:
The UCC25710, LED TV backlight controller
The UCC25710 is an LLC half-bridge controller for accurate control of multi-string LED backlight applications. It is optimized for multi-transformer, multi-string LED architectures. Superior LED current matching in multiple strings can be achieved with this controller and architecture. Compared to existing LED backlight solutions, the multi-transformer architecture provides the highest overall efficiency from AC input to LED load.
The UCC28700, constant-voltage, constant-current PWM with primary-side regulation
The UCC28700 family of flyback power supply controllers provides Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current. Low start-up current, dynamically-controlled operating states and a tailored modulation profile support very low stand-by power without sacrificing start-up time or output transient response.
The UCC28810, LED lighting power controller
The UCC28810 and UCC28811 are general lighting power controllers for low to medium power lumens applications requiring power factor correction and EMC compliance. It is designed for controlling a flyback, buck or boost converter operating in critical conduction mode. It features a transconductance voltage amplifier for feedback error processing, a simple current reference generator for generating a current command proportional to the input voltage, a current-sense (PWM) comparator, PWM logic and a totem-pole driver for driving an external FET.
In the critical conduction mode operation, the PWM circuit is self-oscillating with the turn-on being governed by a transformer zero energy detector (TZE pin) and the turn-off being governed by the current sense comparator. Additionally, the controller provides features such as peak current limit, restart timer, overvoltage protection (OVP), and enable.
Learn more by downloading the reference design below.
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