4 Key technologies of LED lighting
Selection and arrangement of LED
There are three main types of LEDs in terms of structure: one is a leaded (lead angle) LED, the rated current is generally 20 mA, the power is small, and multiple parallel connections are required for lighting; the other is a single-chip surface mount Chip LED, the rated current is generally greater than 50 mA (currently the maximum rated current of the LED reaches 1000 mA), the power is large, and can be used alone; the third is to integrate multiple small power chips to achieve high power, that is, the combination Power LED.
The use of multiple LEDs in parallel has low production costs and is suitable for large-area lighting, but requires a suitable arrangement. When using low-power diodes, in order to make the illumination of a single lamp meet the needs of the coal mining face, multiple diodes must be used in parallel. This brings up the question of how much voltage is used and how to control the total current of the diodes in parallel and in group to meet the requirements of the intrinsically safe circuit. Because the voltage of the intrinsically safe circuit is 24, 18, 12 V, etc., the currents corresponding to the requirements of intrinsic safety should be 400, 600, and 1000 mA. For low-power ordinary light-emitting diodes, the working condition voltage is generally 3 to 4 V and the working current is 20 mA. If 18 V / 600 mA is selected, 30 groups can be connected in parallel, 5 in series as a group, and then a suitable resistor is connected in series. The voltage drop of each diode is less than 3.6V, which meets the requirements of intrinsically safe type and brightness. When one or a group is damaged, it does not affect the work of other diodes or the illuminance.
When multiple LEDs are connected in parallel, the power of a single LED is small and the heat generated is relatively dispersed. As long as the LEDs are reasonably arranged and the Cu area of the printed circuit board is maximized, the heat dissipation requirements can be met.
When high power diodes are used, the design of the intrinsically safe circuit is no longer an issue. The key is how to arrange the diodes to meet the needs of the coal mining face.