Design of LED drive power is not difficult, but must be aware of. As long as the debugging before the calculation, debugging measurement, debugging after aging, I believe that anyone can do a good job LED.
1, LED current size
We all know that LEDripple is too large, LED life will be affected, the impact is much, have not seen what the experts said. Previously asked LED factory this data, they said that within 30% can accept, but then did not pass the verification. Recommended or as far as possible to control points. If the cooling solution is not good, LED must be used to reduce the amount of. Also hope that some experts can give a specific indicator, or affect the promotion of LED.
2, chip fever
This is mainly aimed at the high voltage driver chip of the built-in power modulator. If the chip consumes a current of 2mA, the 300V voltage is added on the chip, the chip power consumption is 0.6W, of course, can cause the chip to heat. Driving chip of the maximum current from the driving power MOS tube consumption, simple calculation formula for I=cvf (consider the charging resistor benefits, the actual I=2cvf, the CGS capacitance C for power MOS tube, V is the power tube conduction when the gate voltage, so in order to reduce the chip power consumption, must be to think of a way to reduce C, V and f. If C, V and F can not be changed, then please think of a way to chip power consumption is divided into chip devices, pay attention not to introduce additional power consumption. A little more simple, is to consider a better heat sink.
3, power tube heating
On this issue, have seen people posted on the forum posted. Power tube power consumption is divided into two parts, switching losses and conduction losses. Note that most of the occasions, especially the LED city electric drive applications, the switch damage is far greater than the conduction loss. Switch loss and the power tube CGD and CGS and chip driving ability and working frequency related, so to solve the heating power tube can be solved from the following aspects: A, can not be one-sided according to the conduction resistance size to select power MOS tube, because the smaller the resistance, CGS and CGD content more. Such as CGS of 1N60 for 250pF or so, CGS 2N60 for 350pF or so, CGS 5N60 for 1200pF, the difference is too large, the choice of power management, enough to be able to. B, the rest is the frequency and the chip driver, here only to talk about the impact of frequency. Frequency and conduction loss is also proportional to, so the power tube heating, first of all to think about is not the frequency of the choice of a bit high. Think of ways to reduce the frequency of it! But to pay attention to, when the frequency is reduced, in order to get the same load capacity, the peak current is bound to become large or large inductance, which is likely to lead to the induction into the saturation region. If the inductor saturation current is large enough, it may be considered that the CCM (continuous current mode) is changed to DCM (discontinuous current mode), so that a load capacitance is increased.