Analyze LED lighting driver power solutions without electrolytic capacitors

The LED lighting driver power supply on the market is usually divided into a secondary architecture and a primary architecture. The primary architecture refers to the DC voltage and constant current required to directly convert the LED illumination from the 220V mains. The structure is relatively simple, and the BOM cost is also relatively low. Low, currently more popular with the market. This article will focus on the primary architecture LED lighting driver power supply without electrolytic capacitors.

Why emphasize electroless capacitors? This is because the working life of the conventional LED lighting driving power supply depends on the Electrolytic Capacitor that the smoothing circuit must use when the AC is turned to DC. We know that the working life of LEDs is up to 40,000 hours, and the life of electrolytic capacitors is only a few thousand hours. Since the life of the system is determined by the life of the electrolytic capacitors used in the power supply components, if you do not want to remove the electrolytic capacitors, then the LEDs The life of the lighting driver and the life of the LED are very mismatched, making it difficult to take advantage of the long working life of LED lighting. This is also the main reason why the industry has been actively developing LED lighting driver power supplies for electroless capacitors.

So why must we use electrolytic capacitors? This is because the LED is a DC current driving element. When the AC power is turned on, a DC stabilized power supply using a rectifying element and a smoothing circuit is generally used. The electrolytic capacitor necessary in the smoothing circuit rises due to the surrounding temperature and its own heat. At 10 ° C, the life is halved, so electrolytic capacitors hinder the life of LED lighting fixtures.

According to our understanding, the current companies that make electroless capacitor LED drive power solutions mainly include Shenzhen Creative Electronics, Xi'an Mingtai Semiconductor, Murata Manufacturing Co., Ltd., Dongguan Huihong Electronics and Shenzhen Guande Technology. The plan of Guande Technology is still in a state of secrecy for the time being, and there is not much to introduce here.

Creative Electronics is based on TK5401 chip of Takion Company of Japan. It replaces electrolytic capacitor with IC . It has 10 times longer life than original LED driver and can last for more than 40,000 hours. It can fully match the life of LED lamp, and this solution is simple in design and small in size. Only 40% of the original LED driver area, this program is mainly used in low-power lighting for home use, the range of application is 3W ~ 20W.

The TK5401 package has a built-in high-voltage power MOS transistor and control circuit. The removal of electrolytic capacitors enables miniaturization, low cost, and long life and high performance of LED lamps.

TK5401 main features: built-in high voltage power MOS tube (650V/1.9Ω); built-in startup circuit, support low power; support universal AC input voltage (AC 85-265V); overvoltage protection / thermal cutoff circuit; adjustable Stream protection.

The PWM control power MOS transistor operates at an average oscillation frequency of 67KHz, and a standard reference voltage (0.3V) is built in to ensure a constant output of the LED output, thereby realizing feedback control. It will stop working when the VCC voltage is lower than the operating voltage.

Although Xi'an Mingtai Semiconductor Co., Ltd. was just established at the beginning of this year, it has already had great strength. At the recent IIC-CHINA Autumn Exhibition Xi'an Station, Mingtai exhibited 20W and 120W electroless capacitors for LED lighting drive power, respectively. Amazing 90% and 95%, respectively, for the indoor lighting and street lighting market. Both products are implemented with their own developed LED drivers, MOSFETs and Schottky diodes. The 120W LED lighting driver is also equipped with complete short-circuit, open-circuit protection and EMC certification testing. These two products have a working life of 80,000 hours, effectively overcoming the industry's difficult problem of LED light source and drive power life mismatch.

It is understood that the 120W LED lighting driver power supply also integrates the power line carrier communication function, which allows the lighting power to be turned on and off remotely. The next step will be to develop dimmable indoor and street lighting solutions based on market demand for electricity.

Dongguan Huihong Electronics Co., Ltd. is a professional manufacturer, developer and marketer of solid state lighting (SSL) system solutions and products for the residential and commercial indoor LED lighting market.

The solution provided by Huihong Electronics eliminates the need for electrolytic capacitors in the smooth loop, has a service life of over 40,000 hours, an efficiency of 85% ± 5% (at 4W output power), a power factor of 90%, and an output power of 4W to 20W. Main functions: input undervoltage protection, input overvoltage protection, MOSFET overload protection, overheat protection, etc.

At the "TECHNO FRONTIER 2010" held on July 21st, Murata made a demonstration of digital power circuits for LED lighting. This demonstration is a power module developed by Murata for Clear Sodick. Its input and output capacitors use the company's multilayer ceramic capacitors (MLCC), which can be built into the tubes of straight-tube LED lighting fixtures. In addition to reducing the size of the product, it also extends the life of the product compared to the use of Aluminum Electrolytic Capacitors. In order to obtain a constant current, a DSP microcontroller is used with a switching frequency of approximately 200 kHz. The output capacitor uses two MLCCs of approximately 5μF. The input voltage supports AC100V and 200V.

It is understood that under normal circumstances, the capacity of the MLCC can not fully absorb the ripple current, but by improving the control of the DSP side, it will not feel the flicker of the lighting fixture. The main circuit uses a non-insulated buck-boost type, and no PFC (power factor improvement) circuit is provided. The external dimensions are 180 mm x 19.4 mm x 6.5 mm.

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