Non-isolated LED fluorescent lamp power supply design
Compared with traditional fluorescent lamps, LED fluorescent lamps can save electricity by at least 60%, and the life span is 5-8 times that of traditional fluorescent lamps. The current design limitations of fluorescent lamps are mainly in two aspects: heat dissipation design and non-isolated power supply design. The heat dissipation design has evolved from the original full PC tube to the half PC and half aluminum tube structure. Each heat dissipation design has its own strengths. At present, the entire industry pays more attention to heat dissipation and heat dissipation design is much more mature than it was a year ago; because It is a new generation of non-isolated LED energy-saving products, so from the beginning of product definition, high requirements have been put forward for non-isolated power supplies, which are mainly manifested in high performance, long life, small size, low temperature rise, and high reliability.
FT880 is a new generation of LED non-isolated power supply products newly developed in response to the various requirements of existing customers on the market for LED fluorescent lamps. It has the following characteristics:
1) FT880 is manufactured using 500V high voltage process, which makes the led non-isolated power supply have the characteristics of dynamic self-powered, feedback zero-current power supply, 2ms ultra-fast start-up, etc., and the long-term working power is more reliable;
2) The led non-isolated power supply can be configured as Buck, Buck-Boost, Boost and other electrical topologies to facilitate the application needs of different LED lamps.
3) FT880 has a PWM/PFM working mode, so that the power can apply the patented "full voltage constant current technology" and can be flexibly configured to different working modes to meet different topologies and LED configurations;
4) The working frequency of the chip is adjustable, and it can be configured as a fixed off-time mode, making the application of led non-isolated power supply more flexible;
5) Add linear dimming and PWM dimming functions for LED applications, which can input dimming signals from outside, or use FMD's patented LED dimming method;
6) The chip has a 2-level current detection mechanism. The non-isolated LED power supply can simultaneously detect LED short-circuit abnormalities and reliably protect the LED;
7) The chip's ultra-low working voltage of 7.5V makes the chip work in a low power consumption state of typically 1mA, which effectively guarantees the price and volume of peripheral devices.
8) The chip can be configured as an opto-coupler feedback type at the same time, which can achieve the mass production of non-isolated led power supply without adjustment, and realize the output opening at low cost.
As shown in Figure 1, the FT880 typical led non-isolated power supply application program. This program uses a high-efficiency low-side Buck topology, uses the patented "full voltage constant current technology" and "zero current power supply technology", and uses passive PFC power Improve the power factor of the program, the output optocoupler is turned on and the output voltage withstand voltage is reduced. The power range of the non-isolated driving LED power supply is 6W~30W. The program also has the following main features:
LED fluorescent lamp non-isolated design
■Full voltage input range: 90~277VAC, which can be used worldwide
■It is specially designed to increase the shielding design for the aluminum tube of fluorescent lamp, and the shielding design in the aluminum tube is necessary.
■Ultra-small volume design, suitable for T8, T10 fluorescent lamp PC tube aluminum tube (height 10mm, width 13.6mm)
■High efficiency, 90% efficiency
■Meet the requirement of Energy Star power factor greater than 0.9
■The overall temperature rise is less than 30℃
■Full voltage and current accuracy ±2%, using patented full voltage constant current technology
■Meet EN55015BEMI requirements
■No-load power consumption is less than 0.3W
■With non-isolated output overvoltage, short, overload, reverse connection
