LED lamp power supply design should pay attention to what elements?
- 2016-05-31 16:35:35
LED power LED lamp is a very important part, if the improper selection, LED lamp not play his rightful property, it may even not use normal lighting. Here LED fluorescent lighting power to do some small suggestion for your reference reference.1.LED fluorescent constant current power supply Why must it?Characteristics of LED semiconductor determines its influenced by the environment, such as temperature, LED current will increase; the increase of voltage, LED current will increase. Long-term than the rated current work, will greatly shorten the LED life. The LED is constant at the temperature and voltage changes and other environmental factors, to ensure that the operating current constant.2.LED fluorescent power to how we can match the light board?Some clients to design the light board, find the power, find it difficult to have a suitable power supply, or too much current, the voltage is too small (as I> 350mA, V <40V); or the current is too small, the voltage is too high (eg I < 40mA, V> 180V), the result is a serious fever, low efficiency, or the input voltage range is not enough. In fact, choose a string and then the best way, applied voltage and current on each LED is the same, but the effect of power able to play the best performance. The best way is to communicate and power supply manufacturers, tailored.3.LED fluorescent power operating current is how much is the most appropriate?General LED rated operating current of 20 mA, some plants used to make the design 20 mA, in fact, this current work is very serious fever, after repeated comparison test, designed to be 17 to 19 mA is relatively ideal design for the recommended 18 mA.4.LED fluorescent power operating voltage is how much?General LED recommended operating voltage is 3.0-3.5V, tested, most of the work at 3.125V, 3.125V so calculated according to the formula more reasonable. M light bead in series the total voltage = 3.125 * M.5.LED lamp series-parallel plate with wide voltage to how wide it?For LED lamp input voltage range in a relatively wide range (full voltage) AC85 ~ 265V, the panel LED lamp series-parallel manner is very important. As the current supply is generally non-isolated step-down power, wide voltage, the output voltage should not exceed 72V, the input voltage range of 85 ~ 265V can reach. That is, the serial number no more than 23 strings. Parallel Number not too much, otherwise the operating current is too large, severe fever, and recommended as the 6/8 and / 12 and. Total current not exceeding 240 mA as well. There is also a wide voltage solution is to first use the L6561 / 7527 of the voltage raised to 400V, then the buck, the equivalent of two switching power supply, cost twice as expensive, this program cost is not high, there is no market.6.LED series-parallel relationship with the PFC power factor and wide voltage is what?PFC power supply currently on the market, there are three cases: one is dedicated circuit without PFC, PFC which is generally about 0.65; one is with a passive PFC circuit, light board horses prepared well, PFC generally about 0.92; also It is active with an active circuit 7527/6561 do, PFC can reach 0.99, but the cost of this program is more expensive than the second option doubled. The second scenario is more so. For passive PFC circuit: also called valley-fill PFC circuit, its operating voltage range of the AC input voltage is half the peak. If the input is 180V, the peak is 180 * 1.414 = 254V, half the peak voltage is 127V, the buck minus differential pressure 30V, maximum output is 90V, so LED lamp beads maximum number of series 28 strings. Therefore, in order to give relatively high power factor, number of series lamp beads can not be too much, otherwise, would not reach the low voltage requirements.7.LED fluorescent power current precision how much would be the most appropriate?Some current precision on the market power of the poor, like the popular market PT4107 / HV9910 / BP2808 / SMD802 programs constant program error of ± 8% or ± 10%, constant error is too large. General requirements ± 3% on it.3% error, 6 in parallel, each of the error is about ± 0.5%, if it is 12 channels in parallel, each of the error is about ± 0.25%, the accuracy is sufficient. Accuracy is too high, the cost will be greatly increased. And in terms of LED, 17 mA and 17.5 mA little effect.8. isolation / non-isolatedUsually made of isolated power such as 15W, LED lamp placed in its transformer bulky, difficult to put in here. Especially for T6 / T8 lamp, almost impossible, generally only do so isolated 15W, 15W more than the few and expensive. Therefore, the high cost is not isolated, non-isolated general more mainstream, the volume can be made smaller, the minimum can be done 8 mm high, in fact, non-isolated safety measures well, the problem does not exist.9.LED fluorescent power efficiencyOutput power (output voltage * LED output current / input power). This parameter is particularly important, if inefficient means a large part of the input power is converted into heat that comes out; if it is contained within the tube will produce a very high temperature, combined with our LED light efficiency than the one dissipate heat, will produce higher temperature superposition.Our internal power supply Electronic parts life will be shortened with increasing temperature. So efficiency is to determine the battery life of the most fundamental factor, efficiency can not be too low, otherwise the power consumed in the heat too. Generally above 80% can, however, about the efficiency of the lamp plate matching connection.10.LED fluorescent lamp power supply DimensionsHeight is a major limiting factor, generally used for tube T6 / T8 size requirements ≤9 mm height can not be too high. T10 tube height ≤15 mm. Length can be rather long, but easy to heat.
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