Views: 0 Author: Site Editor Publish Time: 2021-06-18 Origin: Site
White LED chip are voltage-sensitive devices. Packaging companies have different working currents and working voltages under different packaging brackets. Take a typical package as an example (2835); in actual work, the upper limit is 60mA, but The current will often increase due to various reasons in use. If no protective measures are taken, the LED chip will be damaged after the increased current exceeds a certain time and range.
The main reasons for the damage of LED chip are:
① The sudden increase of the power supply voltage exceeds the voltage regulation range of the lamp power supply, causing the output terminal voltage to rise, and the chip burn out.
② The short circuit of a certain component or printed line or other wires in the circuit forms a local short circuit of the power supply path of the LED chip, which increases the voltage in this place, thereby burning the chip or other components of the circuit board.
③ A certain LED lamp bead is short-circuited due to its own quality damage, and its original voltage drop is transferred to other LED chip.
④ The temperature inside the lamp is too high, which will increase the current of the LED chip and cause the chip to burn out.
⑤The lamp bead board is not waterproofed, and the surface condensed to form condensed water, causing the circuit or lamp bead to burn out.
So, how can we avoid the above problems and protect the LED lamp bead circuit?
First, In order to avoid the first problem, we should take measures.
The power supply of the lamp is generally to pass the AC 180~240V AC power through rectification, filtering, and after stabilization to ensure the output low voltage 12~72V DC power for the LED chip to emit light.
1. Improve the performance of the power supply itself and achieve a wide voltage input; generally, it can guarantee an input voltage of 130V~265V, and the output voltage changes within 3%.
2. Add a linear constant current circuit at the output end of the stabilized voltage, so that the lamp bead current does not change with the change of the input voltage.
Second,Measures we should take to avoid the second and third problems
1. When selecting chip, try to select qualified components to ensure the stability of the light source board.
2. Install as few circuit components as possible on the light source board inside the light source. It is best to install only chip and constant current IC.
Third, Measures to be taken to avoid the occurrence of the fourth and fifth problems
1. In order to ensure that the internal temperature of the lamp is not high, increase the heat dissipation area of the lamp body to ensure that the heat dissipation area per W is 50 square cm.
2. The lamp bead board must be waterproofed with epoxy resin to avoid condensation on the surface of the lamp bead board due to weather.