Første LED controller med aktiv PFC
Linear Technology lancerer LT3799, der er en universal input, isoleret LED controller med aktivt PFC-kredsløb (in english).
As the power saving capability, long life and other benefits of high brightness (HB) LEDs continue to drive the development of a wide range of lighting applications it is no surprise that the growth rate of LEDs continues to accelerate.
In order to continually expand the wide base of applications, LED drivers must continually improve to leverage all of the benefits that LEDs offer. Arguably one of the most widespread emerging applications will be operating HB LEDs from offline AC power. Applications range from replacement bulbs to completely redesigned smart lighting systems.
In the USA and Asia, offline power is generally 110VADC, while in Europe it is 220VADC. Using an AC voltage source to power HB LEDs introduces several new challenges for IC drivers. First, LED drivers must offer high efficiency to preserve the energy savings inherent of LEDs while minimizing costly heat sinking.
Accurate Power Factor Correction (PFC) is also important in maximizing distribution efficiency while simultaneously minimizing harmonic distortion. Additionally, electrical isolation is required for safety and reliability and lighting systems must be compatible with existing circuitry such as TRIAC in wall dimmers. Finally, LED based lighting solutions must not only offer enhanced power savings and reliability, but must also be compact, simple and costs effective.
Linear Technology continues to grow its family of LED drivers to specifically address the demands of these merging LED requirements. The LT3799 provides the first compact, single stage, isolated LED driver with active PFC. It can operate from the universal input range of 90VAC to 265VAC and can power high brightness LEDs requiring from 4W to over 100W.
It uses a unique single stage flyback topology which does not require an optocoupler and offers a PFC of 0.98 and very low harmonic distortion. The LT3799 offers efficiency as high as 86% and is compatible with standard in-wall TRIAC dimmers, enabling very low dimming ranges without any visible flicker. The LT3799 also offers accurate (+5%) LED current regulation under all line and load conditions. Open and short LED protection ensure long term reliability, while a very simple, compact solution footprint enables a wide range of applications.
Key features of the LT3799 include:
• Isolated PFC LED Driver with Minimum Number of External Components
• VIN and VOUT Limited Only by External Components
• Active Power Factor Correction
• Low Harmonic Content
• No Opto-Coupler Required
• Accurate (±5%) Regulated LED Current
• Open LED Circuit Protection
• Thermally Enhanced 16-lead MSOP Package
www.linear.com
