The LED filament lamp is an incandescent lamp that is made of LED from the appearance. In the past, LED light sources had to reach a certain degree of illumination and light area, and optical devices such as lenses must be installed. On the one hand, the effects of light were affected; on the other hand, the energy saving effect of LEDs should be reduced. The LED filaments could achieve 360° full-angle light emission. With a large angle of light and without the need of a lens, it can realize a three-dimensional light source and bring an unprecedented lighting experience. LED filament production technology The LED filament is made by bonding non-back-plated blue LED lamp beads to base strips made of sapphire, transparent ceramics, fluorescent crystals, glass, metal, etc., and then connecting them with gold wires in series, and coating fluorescent powders [3 ]. The flow is shown below. At present, the substrate of the filament lamp is mainly divided into two major categories, rigid substrates and flexible substrates. The hardened stents are generally used in a large amount of ceramic and copper stents, and the flexible stents are mainly FPC (polyimide or polyester thin) and BT (resin). Board), PE (polyethylene) brackets, as shown below. Currently, there are many rigid substrate filaments on the market that are mounted in a positive-mounted chip package. The positive-mounted chip package uses a die-bonding adhesive or eutectic technology to fix the chip on a substrate, and the electrical connection is achieved through a gold wire or an alloy wire. The following figure shows a packaged filament package. . Flexible filaments are usually flip-chip, some rigid substrates are also flip-chip, flip-chip is no lead-flip package, no-lead flip-chip packaging is through the eutectic/reflow soldering technology to electrode contact surface plating tin or The gold-tin alloy electrode chip is directly soldered to the substrate so that the chip can be fixed as well as electrically connected and thermally conductive. When the filament is lighted, because the substrate has a certain degree of transparency and the refraction of the fluorescent adhesive layer, the filament has a 360° light emitting characteristic, so when the adhesive is dispensed, the filament is usually subjected to front and back dispensing, and the phosphor encapsulates the LED filament. Ensure that blue light does not fall out and prevent blue light from damaging the retina. Three LED filament lamp drive power 1. The resistance-capacity step-down power supply to be eliminated 2, the current mainstream non-isolated switch constant current drive power 3, emerging high-voltage linear constant current drive power Today, the new generation of drive power chips and Solutions with smaller footprints can meet the requirements of filament lamps without plastic parts. At present, the grid voltages of various countries in the world are different. In many countries, there are two different grid voltages that are used simultaneously, such as the United States, Canada, Mexico, Japan, Brazil, and Vietnam. The grid voltage varies from AC100V-240V with a large span. This requires that the filament lamp power supply can be applied to AC100V-240V input voltage. The basic operating voltage and current of the filament lamp is DC150V/10-30mA. Therefore, the power supply will be designed for step-up (AC90-130V input), step-down (AC180-265V input), and automatic lift according to different input voltage ranges. Pressure (input AC90-265V) Three different modes to adapt to different grid voltages. Filament lamp mainstream product driving power of the general parameters 1. Candle lamp power: 2W, 3W, 4W; Output voltage is DC150V, output current is 10-12mA, 14-15mA, 20-22mA; 2. Bulb power: 2W, 4W, 6W, 8W; Output voltage is DC150V, output current is 10-12mA, 22-24mA, 33-36mA, 44-48mA. SM2082C linear constant current filament lamp solution The SM2082C is a single-channel linear constant current driver IC. The output current is set to 5mA~60mA by an external resistor, and the output current does not change with the OUT port voltage of the chip. The system structure is simple, the number of external components is small, and the cost of the solution is low. Filament lamp program application principle (Figure 1): The SM2082C is available in both ESOP8 and TO252 packages and can be used for drive solutions for various interfaces such as E14 and E27. In the above figure, the E1 capacitor can be designed according to the customer's design. If the E1 capacitor is omitted, there will be a strobe of the AC. The following figure shows the scheme PCB schematic of the E14 interface (Figure 2): This solution PCB adopts SM2082C design in ESOP8 package. It enhances heat dissipation through spotted copper leakage treatment. It is compatible with electrolytic capacitors and can pass EMC certification. Its output current range is 10mA to 15mA, and it supports single voltage input of 110Vac or 220Vac. Voltage fluctuation range Better than ±10%. Since the SM2082C is a linear constant current scheme, the total voltage of the LED filament is required to be high, and the output current varies greatly when the input power grid fluctuation range is large; therefore, a non-isolated constant current driving scheme can be adopted when the input voltage fluctuates greatly. . SM7313P Non-Isolated Constant Current Driver Filament Lamp Solution SM7313P is a high-precision and high-efficiency non-isolated LED constant current drive control chip. The chip adopts a BUCK circuit structure and works in a fixed frequency mode. It can realize a small output current and high voltage within 5W using a relatively small chip inductor. Program. The constant current accuracy can reach ±3% of the full voltage range, with few external components and low solution cost. SM7313P also has LED output protection function such as open and short circuit protection. The power board of this solution has a diameter of 15.4mm and a height of 14mm, and can be directly placed in the E14 lamp head. No white plastic kit is required. When 30V/20mA filaments are used in two strings and one, the input range of 100Vac~265Vac can be supported. The filament lamp scheme realized by SM7313P, the voltage of LED filament is no longer limited, 30V to 150V and other voltages are optional. Certainly, SM7313P also supports the application of E27 interface specification, the output current can reach 40mA, when the output current is bigger, can adopt the chip such as our company SM7315P or SM7307 to carry on the scheme design. SM7315P/SM7307 Non-Isolated High Current Filament Lamp Solutions SM7315P and SM7307 are non-isolated BUCK LED constant current driver control chip. High-voltage self-starting and power supply technology eliminates the need for auxiliary windings to provide power and does not require any compensation components to achieve a constant output current. There are few peripheral components and the solution cost is low. The schematic of the SM7307 solution is shown in Figure 4. Figure 5 is a physical diagram of the filament lamp scheme implemented by the SM7307. The diameter is 19mm. The certification is compatible with non-certification. The EE8.3 small inductor can be used to support multiple specifications below 6W. Applications 150V/35mA, 60V/60mA, 60V/80mA, etc. . The SM7315P is compatible with the SM7307's PCB. The feedback loop can be omitted and the circuit is simpler. Some typical specifications of the current filament lamp program are shown in Table 1: Fiber Optic Accessories,Fiber Optic Cable Connectors,Fiber Optic Adapter,Fiber Cable Connectors Huizhou Fibercan Industrial Co.Ltd , https://www.fibercan-network.com
