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6

Like Aaron said, a topology with a transformer allows for better control of the step down/step up voltage. A duty cycle of 7% seems fine on paper, but in reality you should aim for closer to 30%. In an application with changing load that 7% nominal duty cycle can drop down to 1 or 2% with low or no load. When using a PFC, especially a boost PFC, the 400V(...


5

The usual method is to use the comparator with a triangle clock generator with the linear error converted to PWM (pulse width modulation) to control the buck regulator. I show my example below as a simplified version of this IC. (not optimized) Here a simple Schmitt astable clock can be integrated by some RC inside to create a fairly linear triangle at ...


4

With a simple buck converter, you only have one degree of freedom, the duty cycle. And as you are noticing, the duty cycles for those input:output ratios are very small. With a transformer design like a flyback, you get two degrees of freedom, the duty cycle and the transformer winding ratio. Usually you design the winding ratio so that you can be in the ...


2

for 5V operation you'll need to loose the diode D1 and THE voltage regulator formed by R3 R4 R5 R7 Z2 C13 Q1 and feed the apropriate voltage (probably 5v) to the Q1 terminal closest to E4 probably best to measure that first. you can get some reverse polarity protectopn by putting a reversed diode in parallel with the input. but if you have a 100A 5V ...


2

Voltage generator, maybe? I used this text in school and they use the Vg nomenclature from the get-go. I don't think there's anything special about it. On page 3, they introduced Vg for the first time: So Vg is just the way they call the input voltage to the converters in the text.


2

Why is only the first turn in the coil hotter compared to other two turns? The inner turn will get hotter because it has less surface area to dissipate heat produced and, it is enclosed by outer turns that themselves will push heat towards that inner turn. In this, only the turns of the top part seem to be hotter compared to the bottom. It looks ...


2

Since the input capacitor has a low ESR the surge current may be up to 12V/ESR. If the supply starts up with the Buck connected then a slow start might work with a suitable ICL, Inrush Current Limiter. Ic = C dV/dt Choose 1A or get a variety of values with a 12~22 Ohm minimum R @ 25°C TI's standard design shows 27uF 40 mOhm for Cin. Thus if the 12V ...


1

For consumer use, it is not popular, for light industry it is not common, but for heavy industry (MVA generation) as long as somewhere in the system design there is isolation and safety earth ground, there is no restriction for isolation if no service access is needed or safety hazard imposed in use. You are likely never to see the latter unless you are ...


1

The available power is based on Pin = Pout, BUT, if you reduce the voltage into a fixed value resistor, then the current reduces appropriately as per Ohm's law. Your confusion is about the power staying constant, it is available if you change the resistor...


1

it's bugging me because I'm essentially connecting Vin- and Vout- on the converter and if that was okay then why would they even have put Vout- on there? You probably have an isolated converter. If you need to maintain galvanic isolation between the input and output (for example, for user safety), then you would not connect VIN- and VOUT-. If you don't ...


1

So this is what the input stage looks like from your picture (assuming there is nothing on the back): simulate this circuit – Schematic created using CircuitLab Q1 is a power N-MOS (FQD2N60C). Its Gate is connected in series with 120kOhms from V+ and the Drain is connected in series with 20Ohms from V+. Z2 is some sort of fuse or diode or diode fuse?...


1

I have produced several hundred thousand products using MC34063 or equivalent. I am "familiar with its operation." However, YOU have not given us enough information for us to be sure what your problem is. The biggest problem is approximately what you say BUT from "the tone of voice" that comes across it sounds as though you think this is the "fault" of the ...


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