1, chip fever
This mainly for built-in power of the modulator high pressure drive chip. If the current consumption chip for 2 mA, 300 V voltage and above chips, chip power consumption is 0.6 W, of course, can cause fever of the chip. The maximum current drive chip from driving power consumption of MOS tube, the simple formulas for the I = CVF (considering the resistance of the charging efficiency, the actual I = 2 CVF, including for the power of the c MOS tube CGS capacitance, v for power tube turn-on of the gate voltage, so in order to reduce the chip power consumption, must think of a way to reduce c, v and f. if c, v and f can’t change, so please think of the chip to the device to the power consumption chip, careful not to introducing additional power consumption. More simply, is considered better cooling it.
2, power tube fever
On this question, also meet someone in power nets BBS have posted. Power tube power consumption into two parts, switches loss and conductivity loss. Note that most cases markedly
fluorescent led bulbs the utility driver application, switch damage to far outweigh the conduction loss. Switch loss and the power of the tube CGD and CGS and chip drive ability and work on frequency, so to solve power tube of fever can from the following several aspects solution: A, can’t one-sided according to conduction resistance size to choose MOS power tube, because the small resistance, CGS and the greater the CGD capacitance. Such as 1 N60 CGS for 250 pF the left and right sides, 2 N60 CGS for 350 pF the left and right five N60 CGS for 1200 pF or so, the difference is too big, choose power tube than is necessary. B, the rest is frequent and chip drive ability, here only talk about the influence of frequency. Frequency and conduction loss also become direct ratio, so power tube fever, you have to think about the frequency of choice is a little shrill. Think of a way to reduce the frequency!!!! But want to notice, when the frequency decreases, in order to get the same load ability, current peak inevitable to be gigantic or inductance becomes larger, this may lead to inductance into saturated area. If inductor saturation current is enough adult, can consider to will CCM (continuous current mode) change into DCM (the continuous current mode), so we need to raise a load capacitance.
3, working frequency frequency reduction
This is also the user in the commissioning process more common phenomenon, the highest frequency reduction by two aspects cause. The input voltage and load voltage of the proportion of the small, system interference. the former, pay attention not to load voltage setting too high, although load voltage high, efficiency will be high. For the latter, can try the following several aspects: a, will set minimum current again small point; B, wiring clean point, especially sense the critical path; C, will choose little point or inductance inductance of the magnetic circuit choose closed; D, add RC low pass filtering it, the effect is not good, C consistency is bad, a deviation, but it should be enough for lighting. No matter how to frequency reduction benefits not merely bad, so be sure to solve.
4, inductance or transformer choice
Finally to that point, I haven’t introduction, can only talk nonsense point of saturated impact. Many users of reaction, the constant drive circuit, with a production of inductive no problems, with the inductance current production B is smaller. In that case, want to see inductor current waveform. Some engineers didn’t pay attention to this phenomenon, direct regulation sense resistor or work to the contemporary need frequency that this could seriously affect the service life of fluorescent led comparison. Say So, in before the design, reasonable calculation is crucial, if the theoretical calculation of the parameters and testing parameters of the poor little far, want to consider whether frequency reduction and transformer are saturated. Transformer saturation, L will become smaller, lead to transmission delay caused by a sharp rise in the peak current increment, then LED peak current also follows to increase. the average current unchanged, under the premise of can simply look at the light failure.
5, fluorescent led light
We all know LEDripple too big words. LED life be affected, how much impact, didn’t also see which experts said. Ago asked LED factory the data. They pay 30% less than can be accepted, but then not validated. Suggest or try to control minor points. If heat dissipation solve bad word, LED must drop the forehead to use. Also hope there is a precise index expert can give, or influence the promotion of LED.
