As a fourth-generation lighting fixture that is green, energy-saving, energy-saving, and long-lived, LED light source has sprung up, attracted wide attention, and developed rapidly. The current LED light source is a semiconductor device that operates at a low voltage (VF=2â†’3.6V) and a large current (IF=200â†’1500mA), and must provide a suitable direct current to emit light normally. The technology of direct current (DC) driving DC LED light source has become more and more mature. Since the power supply used in our daily lighting is high voltage alternating current (AC100-220V), it is necessary to use the buck technology to obtain lower voltage. The transformer or switching power supply is stepped down, and then the alternating current (AC) is converted into direct current (DC), which is then converted into a direct current constant current source to cause the LED light source to emit light.
Therefore, the system application scheme of the DC-driven LED light source must be: transformer + rectification or switching power supply + constant current source. LED lamps must have a certain amount of space to house this power module, but for E27 standard screw luminaires, the space is very limited and difficult to place. Whether it is via transformer + rectification or switching power supply step-down, the system will have a certain amount of loss. When DC LED lamps are switched between AC and DC, about 15 to 30% of the power is lost, and the system efficiency is difficult to achieve more than 90%. . If the LED light source can be directly driven by alternating current (AC), the system application scheme will be greatly simplified, and the system efficiency will easily reach 90% or more.
It appears that LED driver ICs are critical devices in LED luminaires. At present, there are more than ten domestic LED driver IC development and manufacturers. The characteristic requirement of the LED driver IC is the consistency and constancy of the current output. At present, the domestic lighting LED driver IC product technology still uses the traditional DC/DC buck, boost constant current mode, and the constant current source circuit composed of PWM controller. At present, these two types of LED driver IC technology are still in the product. The initial stages of development, especially those limited to low-voltage wafers, affect the increasingly demanding higher voltage applications. With the expansion of lighting applications, LED driver ICs are moving toward mid- to high-end and highly integrated, multi-chip package (CMC) technologies.
The basic technical element of LED light source application is that it must meet its VF (forward voltage) and IF (forward current) requirements. VF is to establish a normal working state for the LED light source. IF is to promote the LED light source to emit light, its brightness and current. The size is proportional; in response to the development of LED driver IC technology, the input voltage (Vin) range of the LED driver IC will be wider (DC5C-45V), and the output constant current accuracy is higher (1%); in view of more and more LEDs The lamp uses multiple high-power LED series application technology, which requires the output voltage of the new generation LED driver IC to be increased to 60V-100V. This requires a high-voltage process to produce the wafer of the LED driver IC; the LED driver IC output withstand voltage is improved to It opens up new market segments in markets with high voltage requirements such as automotive electronics, automotive lighting, and high-light lighting.
China Resources Weiwei Technology Co., Ltd. is a domestic integrated circuit design company that is involved in the design and production of LED driver ICs earlier. Its PT4115 is a typical Vin wide voltage input (DC6V-30V), high current constant current output (1.2A) DC. /DC buck LED driver IC, PT4115 is a continuous inductor, current conduction mode buck constant current source, it has a wide DC 6V to 30V input voltage range, breakdown voltage >45V, output 200mA--1200 The mA constant DC can meet the requirements of driving 1-7 high-power LEDs in series or N low-power LEDs in series and parallel. The driving constant current size can be set according to the application scheme. PT4115 uses frequency jitter technology to effectively improve EMI; PWM dimming from full-scale down to zero, safe and reliable, dimming ratio up to 5000:1; SOT89-5 package, chip die (Die) Thermal conduction is very effective by dissipating heat directly from the exposed metal plate (Exposed PAD). The over temperature protection function (TSD) is set inside the PT4115 to ensure stable and reliable operation of the system. When the IC chip temperature exceeds 160 Â°C, the IC will enter the TSD protection state and stop the current output, and when the temperature is lower than 140 Â°C, the IC will return to the working state. The PT4115 can use the principle of analog dimming and the negative feedback of temperature on the LED current to realize the dynamic temperature control of the LED lamp. Just add a thermistor or PN junction at the dimming end (DIM). Plus the rectifier bridge PT4115 can be applied to AC 12V, 24V power supply LED lamps. The application of the PT4115 is very simple, with only four peripheral parts. With a working efficiency of 97%, the PT4115 is a true green driver IC. PT4115 is widely used in various types of LED lamps such as MR11, MR16, underwater lamps and street lamps that use LED lamps. In order to effectively shorten the design cycle of LED luminaire manufacturers, China Resources Converse's one-step promotion model provides LED luminaire manufacturers with DEMO boards, circuit diagrams, PCB boards and BOMs that can be directly used for MR16 production, providing timely and timely use for customers. Thoughtful technical support.
Lighting LED driver IC development direction
The LED light source is a long-life light source with a theoretical life of up to 50,000 hours. However, the application circuit design is unreasonable, the circuit components are not properly selected, and the LED light source is not well cooled, which will affect its service life. Especially in the application circuit, the electrolytic capacitor, which is the output filter of the AC/DC rectifier bridge, has a service life of less than 5,000 hours, which is a roadblock for manufacturing long-life LED luminaire technology. The only feasible advanced solution is Design and manufacture a new generation of LED driver ICs that can eliminate electrolytic capacitors in application circuits. Japan's new LED driver IC--TK5401 design eliminates the need for electrolytic capacitors on application circuits, and has a lifetime of up to 40,000 to 50,000 hours, just in line with LEDs. Lifetime matching. The use of this IC can reduce the PCB board area to 40%, which really saves the space of the power module, which is also the design of the LED lamp .
The design of the new generation of LED driver ICs must break the traditional DC/DC topology design concept, such as constant voltage, step-down type without hysteresis control, constant frequency constant current control, and use of electronic transformers using halogen lamps. The light source flashes and the multiple lamps are not connected in parallel, etc.; the LED driver IC must also be able to pass EMC, safety, CE, UL and other certifications in various application circuits; the application circuit strives for simplicity, and the use of fewer components is also a customer. Cost reduction is a dream, and market competition is necessary; isolated and non-isolated applications have always been the focus of business security and efficiency; increase the duty cycle of the PWM controller and so on.
0.5W-3W LED light source and LED driver IC The next-generation chip integrated in a CMC package has been produced in small batches. The display LED driver IC is developing in a highly integrated multi-chip CMC package; it can be directly driven by alternating current (AC). The new generation of light-emitting, special topology AC LED light source production technology is becoming more and more mature, and will create another new era of LED lighting technology.
IC manufacturers provide end-users with solutions that can be directly used for production, making the upstream and downstream of the industry chain directly docked, saving time, money, and products.
In recent years, integrated circuit manufacturers have been able to make integrated circuit new products into mass production applications in a short period of time, shortening the customer's design cycle, and as the upstream enterprises of R&D and production integrated circuits have stepped up their efforts. The development of the system application program on the product application side adopts the turnkey project mode, so that the downstream terminal factory that purchases the main chip can directly market according to this scheme in a short period of time. For example, Taiwan MTK provides a system solution for selecting mobile phone chips for direct production of mobile phones; China Resources Weiwei Technology Co., Ltd. designs and manufactures LED driver ICs, and provides LED lamp manufacturers with direct use for the production of MR16, E27, PAR30, PAR38, DEMO of the fluorescent lamp and circuit diagram, bill of materials (BOM). This has become an inevitable trend for the upstream enterprises that produce integrated circuits to cooperate more closely with the downstream enterprises that produce the final products, to survive together, to develop together, and to prosper together.
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