It is a general trend that led lighting gradually replaces traditional lighting. However, LED general lighting has many challenges, such as power density, power factor correction (PFC), space limitation and reliability. Ansenmey semiconductor is committed to providing a wide range of solutions for LED lighting, and launched a variety of products that meet the latest LED lighting standards, including AC-DC LED driving power solutions for general lighting.
General lighting challenge and AC main power supply LED driver topology
Due to the total light efficiency requirements and heat dissipation limitations of LED, energy efficiency is particularly important for low-power applications; In many cases, even lower power applications require power factor correction and harmonic processing; High driving power density is required in space limited applications, especially in alternative bulb applications; The overall power supply reliability is very important to the service life of the whole lamp; Wide input power supply voltage range shall support up to 277 VAC; Compatible with triac dimming requirements. In addition, LED general lighting should also comply with evolving standards and Safety specifications, such as “Energy Star” and IEC requirements.
According to the application requirements (size, energy efficiency, power factor, power, driving current), there are many topologies to drive LEDs with AC main power supply. Ansenmey Semiconductor provides a variety of power solutions for a variety of lighting applications.
1) Power factor correction scheme
The 160 W power factor correction (PFC) boost scheme of ncp1611 or ncp1612 of ansenmey semiconductor adopts non isolated boost topology, and the light load energy efficiency is higher than that of traditional CRM PFC; No additional components, high reliability and safety. The scheme adopts current controlled frequency reversal (CCFF) CRM, which has the characteristics of boost or bypass diode short-circuit protection, pin open / short-circuit protection, optimized transient response, soft overvoltage protection, input undervoltage detection, low total harmonic distortion configuration, overheating shutdown and so on.
Such PFC schemes also include ncp1607, ncp1608, ncp1615 and ncp1654 (non isolated boost); Ncl30000 (isolated single-stage flyback, non isolated step-down); Ncl30001 (isolated single-stage flyback); Ncl30002 (non isolated step-down); Ncl30060 (single-stage flyback or step-down).
Taking ncl30000 as an example, two configurations can be selected for the “average current stabilizing” topology, one is the step-down configuration (including the tap inductance step-down configuration); The other is buck boost configuration. The inductor is not connected in series with the LED, and the input current waveform or distortion has nothing to do with the output voltage drop. It can carry out primary thyristor dimming and is suitable for isolation and non isolation schemes. The energy efficiency of isolation scheme is 80-85%.
2) Primary end control offline scheme
Primary steady current (PSR) is also called primary control. The primary end control off-line LED driver does not use optocoupler, and has ± 1% (typical value) precision LED current stabilization accuracy, wide VCC range, high-energy efficiency quasi resonance control, strong protection characteristic combination, and wide operating temperature range (- 40 to + 125 ℃); It supports flyback and buck boost topology, and the power factor with passive PFC input is about 0.9; This series can be applied to LED bulb replacement, off-line LED driver, embedded lamp, indoor / outdoor key lighting, task lamp and LED electronic control device.
The optional devices include ncl30080a / B, ncl30081a / B, ncl30082a / B and ncl30083a / b (passive PFC control); Ncl30085a / B, ncl30086a / B, ncl30087a / B and ncl30088a / b (active PFC control). Its dimming control includes non dimming, 3-step / 5-step dimming, analog / digital, bidirectional thyristor / trailing edge trigger dimming, etc.
3) AC-DC switching regulator
Ansenmey semiconductor’s switching regulators for isolated flyback and non isolated converters include ncp1010, ncp1011, ncp1012, NCP1014 / 15, ncp1027 / 28, ncp1072 / 5, ncp1076, etc. These devices are current mode with peak current limits from 100 mA to 800 ma. These schemes integrate MOS transistors, which are suitable for isolated and non isolated applications. They support secondary PWM dimming, analog dimming or dual brightness level dimming, with energy efficiency of up to 75-80%.
4) High power factor boost scheme for high voltage LED string
High voltage multi node LEDs are becoming more common as suppliers tend to better optimize LEDs to improve the overall light efficiency of the system and introduce more specialized LEDs. These LEDs have a forward voltage of 24 to 200 V per package and can be optimized for fixed-point lighting, omnidirectional lighting or linear lighting. In order to achieve this goal with low number of components and standard ready-made inductors, ncp1075 single-chip high-voltage switching regulator and high-precision ncp4328a constant current / constant voltage controller are used in the circuit.
The energy efficiency of the scheme is higher than 90%, with 20 ms fast start-up time, led open circuit protection, available inductance, power factor higher than 0.95, and power capacity greater than 10 W when ncp1075 is adopted. The applications are mainly led bulbs and tubes, low-power light sources and lamps, electronic control devices and LED drivers.
5) AC-DC switch controller
The switching controllers for isolated and non isolated buck and buck / boost converters have fixed frequency NCP1200, ncp1203, ncp1218, ncp1219, ncp1230, ncp1234 / 6, ncp1237 / 8 and ncp1250 / 1 / 3; There are also quasi resonant ncp1207a, ncp1308, ncp1337 / 38, ncp1377, ncp1379 / 80 and ncp1336. Switch controllers for non isolated buck converters include lv5011md, lv5012md, lv5026mc, lv5029md, ncl30002 and ncl30105. In addition, there are switch controllers ncp1392 / 3 and ncp1398 of resonant half bridge converter and switch combination controllers ncl30051 and ncl30030.
6) Offline buck LED driver
Ncl30002 is an energy-efficient CRM control method supporting high power factor or low ripple step-down topology. It has 485 MV peak current sensing accuracy of ± 2% (typical value) and as low as 24 μ Starting current of a (typical value); Maximum VCC up to 20 VDC; Gate driver with 500 mA source / 800 Ma drain MOSFET; Wide operating temperature range – 40 to + 125 ℃. Its applications include LED bulb (including small candle lamp) replacement, embedded lamp, indoor / outdoor key lighting and task lamp.
7) Non isolated off-line Buck Controller
Lv5026mc is a non isolated off-line step-down controller, which supports different dimming control (triac, analog and PWM), selectable switching frequency (50 kHz or 70 kHz) and low-noise switching system; It has short-circuit protection, soft start and built-in triac stability functions. Applications include wall lamp, task lamp, step lamp and led bulb replacement.
8) Dimmable LED driver
Lv5026mc, lv5029md, lv5011md and lv5012md in lv50xx are dimmable LED drivers. Taking lv5011md and lv5012md as examples, both switching frequencies are 70 kHz, which can improve the power factor and have the functions of external regulation, reference voltage, overvoltage protection and overheating shutdown. The difference between the two is the dimming mode, which can be used for small dimmable LED bulbs, offline LED drivers and embedded lamps.
9) Constant current regulator (CCR) with non isolated linear LED driver topology
One is the low current LED string driver CCR nsic2020 (120 V, 20 mA). When the AC voltage rises, the current remains constant. After reaching the LED threshold voltage, there is no delay in conduction. When the voltage is low, the LED brightness is high, which can prevent the LED from being affected by voltage surge. The other is used for low-cost T5 LED lamp. CCR nsic2050 (120 V, 50 MA) led driver is adopted, which can directly AC drive LED, no leakage current, and stable current can protect led.
10) LED power supply for street and area lighting
Instead of high intensity gas discharge lamp (HID) or high pressure sodium lamp (HPS), large LED array shall be used. According to different end products, LEDs can be configured in different structures. One method is to convert the AC input voltage into DC regulated output and supply power to multiple parallel LED light strips. Another method is to provide constant current to directly drive the LED, eliminating the built-in linear or DC-DC conversion section in the light bar.
The second method is designed to match the “Energy Star” version 1.1 light source specification, and its features include: general input range of 90 – 265 VAC (changed components can support 305 VAC); The maximum output power is 60 W (the changed element ncl30051 supports a maximum power of 250 W); Power factor PF is greater than 0.9 (50-100% load, with dimming); Harmonic content shall comply with iec61000-3-2 class C standard; More than 90% energy efficiency at IOUT = 1000 MA / VF = 35 to 45 V; Constant current output current range: 0.7 – 1.5 A; Output voltage range 35 – 50 V; Output open circuit and short circuit protection, over temperature protection, over-current protection – automatic recovery, over-voltage protection – input (OVP high voltage) and other protection characteristics.
Using its core expertise and advantages in power management, energy-efficient power supply and packaging, ansenmey Semiconductor provides control and driver devices that meet various specifications for LED lighting applications, especially general lighting. These solutions adopt unique LED driving power architecture, analog and dimming technology, flyback converter and non isolated topology, which are suitable for various general lighting applications and provide rich choices for the implementation of these devices.
Source; Led network