Common problems and solutions in the design of the LED power supply _

Common problems and solutions in the design of the LED power supply of 2020-986 07 - 01 16:29:37 in current life, in order to save energy, LED by large, but LED all need to have a power drive, it is good or bad will directly affect the service life of the LED, so how to make an LED driving power supply is the key of the LED power supply designer. 1. Drive circuit directly influences the life of what we call the LED drive including digital drive and simulate the drive and digital circuit driver drive index word, including digital dimming control, RGB full color changes, etc. Refers to the analog circuit to simulate the drive and drive, including AC constant current switching power supply, DC constant current control circuit. Driver circuit is composed of electronic components, including semiconductor devices, resistor, capacitor, inductor, etc. , these components have life, any device failure will lead to the failure of the whole circuit or part function failure. 2. Heat dissipation problem of LED cold light source, work junction temperature cannot exceed the limit, when the design should leave some allowance. The whole design of lamps and lanterns should consider good appearance, easy installation, light distribution, many problems such as heat dissipation, to seek balance in the many factors, so that the overall lamps and lanterns is the best. Some don't know much about the designer to power LED lamps and lanterns, give the LED heat dissipation space is larger, to power the heat dissipation space is smaller. Is generally designed after looking for the right power supply to form a complete set of lamps and lanterns, bring certain difficulty to the power of form a complete set. Often encounter because of small space inside the lamp or the internal temperature is higher, and the cost control is low, cannot match to a suitable power source. In to consideration in the design of the LED heat dissipation of heat and power supply, the overall control the temperature of lamps and lanterns, in order to design a good lamps and lanterns. 3. Design of power supply in A. Power design. While LED luminous efficiency is high, but there is 80 - 85% of heat loss, which has 20 - inside the lamp 30% ( $10. 6626). Degree of temperature rise, if the room temperature is 25 degrees, there are 45 - inside the lamp 55 degrees, the power supply work in high temperature environment for a long time, to ensure that the life will have to increase the power allowance, generally until 1. 5 - 2 times the allowance. B。 Component selection. 45 - internal temperature of lamps and lanterns 55 degrees, internal temperature rise and power about 20 degrees, is to achieve the temperature of 65 - element accessories 75 degrees. Some components in high temperature condition parameters will offset, and some will shorten the service life, so the device to select can be used in high temperature for a long time, pay special attention to electrolytic capacitor and wires. C。 Electrical design. Switching power supply for LED parameter design, mainly is the constant current parameter, the size of the current decision LED brightness, if the current batch error is larger, the whole batch of the brightness of the light is not uniform. And the change in temperature can make the power output current offset. Typically batch error control within the plus or minus 5%, can ensure the brightness of the light. Positive pressure drop is misaligned, LED power supply design of constant current voltage range to include the LED voltage range. D。 PCB board design. The size of the LED lamps and lanterns to power small ( Unless it is power source external) , so higher requirements on the PCB design. Should stay a safe distance from enough, for the power of the input and output isolation, a side and secondary side circuit pressure 1500 - requirements 2000 vac, at least on the PCB to keep enough distance to 3 mm. If there is no space to ensure a safe distance from the case to use other measures to ensure insulation, such as punching on PCB, insulation paper, insulation potting glue, etc. Another cloth plate to consider heat equilibrium, heating element to uniform distribution, cannot be placed centrally, avoid local temperature rise. Electrolytic capacitor away from heat source, slow down aging, prolong service life. E. Use the parameters. Power supply depends mostly on the choice of constant current and constant current voltage range. Constant current value choice for the LED standard current offset. The choice of voltage range wants moderate, try not to choose major, avoid the waste of power.