# Tag Info

11

It goes into the output capacitor. The pulse is short enough and the capacitor is large enough that it can be engineered not to significantly make the output voltage rise, maybe by few percent, as long as it is within limits so it's not too high. The output waveform also depends on how fast the regulator reacts to this via feedback loop and compensation as ...

7

No, even if that was only a 5V supply for digital logic, it is hazardous and unsafe. So at least your rectangle of unsafe voltages is too small. It will extend to all components and wires going into the box. That is because what you drew as the 0V or ground symbol, will actually have peaks of minus 325V in EU and half of that in the US during the negative ...

5

The inductor energy goes into the output capacitors, causing some amount of unavoidable overshoot in the output voltage. Worst case is a load release at the peak inductor current, and you can calculate the overshoot from the deltas in the inductor energy ($1/2\ LI^2$) and capacitor energy ($1/2\ CV^2$).

5

The circuit you mentioned could be described as a pwm current source. It uses its relatively large 2 ohms current sensing resistor, as well as the resistor R3 at the base of Q1 to limit its output current. A quick simulation shows that there is significant power dissipation in the other Q1 (BD140) during the on phase of the pwm cycle. So to answer your ...

3

I'd go straight for a single stage dual phase converter like this: - One for each motor should do the trick. Be warned though, this is not something to be undertaken without good tools and PCB design skills. You will certainly find more designs available if you split the power requirements by four and concentrate on a single regulator per motor load. ...

3

It is not only unsafe as stated by Justme, it will also blow imediately one of the rectifier diodes (one of the two diodes connected to GND on the left side of your rectifier symbol) because it shorts the AC input. The reason is that one of the AC terminals is also grounded which is not shown in your diagram (the other one of those two diodes will never be ...

2

Having just read about the TL494 in the last 30 minutes or so, I have to conclude that it certainly $\color{red}{\text{DOES}}$ need frequency compensation and that back in the day when it came out, people must have realized that and naturally "slugged" the output from pin 3 with a capacitor to either ground or back to pin 2. It's a poor data ...

2

So I have actually tried is with a cheap normal buck boost with constant voltage and constant current fuction. I have a 12v volt system so I set the the output to have 14.7 CV and 3 amps CC with 50 watts solar panel. In bright sunlight with the baterry charging, it pulled the solar panel down to 8 volts (minimum operating voltage of the BB converter) while ...

2

When someone asks what amount of phase margin (PM) is acceptable, the answer should be "what transient response do you want?". If you need a fast-recovery system and tolerate some overshoot or, on the contrary, you cannot suffer overshoot at all and want the most conservative design, then these are two different phase margin goals. For a second-...

2

Shorting the buck regulator output to GND probably will not damage any of the downstream components. BUT ... It NEVER is "recommended" to apply a dead short to the output of a switching regulator. Some linear regulators, such as in lab or bench supplies, use this technique to set the output current limit, but your circuit is not that. This part ...

1

What makes this circuit work in that situation? Base current to the driver transistor is limited by the 15k resistor, which in turn limits peak charging current due to current gain of the transistors. Typical HFE of the BC847A is ~180 at 30 mA, and the BD140 is ~40 at 1.5 A. With a control current of ~170 uA this would supply a charging current of 0.00017 x ...

1

Look at how appliances are designed to be safe. There are no appliances I can think of off the top of my head that use 1kW-ish power and have that power isolated before it is consumed. Something like a stove may have isolated control circuits but the power circuits will not be isolated from the mains. Similarly with an air conditioner, a washing machine and ...

1

Here's the block diagram of the LM3150 internals. So, VCC is normally regulated to ~6V by an LDO. This provides power to the drivers that do the actual switching. Because the role of the drivers is effectively to charge capacitors (the MOSFET gates), the important question is how much current the LDO can source on a consistent basis. C_VCC and C_BST ...

1

This is a really old app note from TI, and I believe they just lowered the loop gain until it was stable, by killing the error amp gain: "To increase the stability of the error-amplifier circuit, the output of the error amplifier is fed back to the inverting input through RT , reducing the gain to 101." So the loop response is probably terrible, ...

1

MOS1 is backwards, so right now the output voltage will just be the input minus the voltage drop from the body diode. It is, however, the correct type (you should be using an N channel FET, not P). Typically you need a high-side gate driver with a bootstrap capacitor to use one though. I recommend operating the converter in open loop at 50% duty cycle. ...

1

You are using an N-channel device as your pass transistor when you should be using a P-channel device in this type of circuit configuration. Look at the parasitic diode component across MOS1 - you can see that it will be conducting all the time. Change it to a P-channel device like this: - As for not finding an isolation component in PSIM, you should be ...

1

Being the author of these free ready-made SIMPLIS templates, I can answer the questions. When the PWM artificial ramp is of 2-V amplitude, you have to limit the maximum voltage excursion of the op-amp to limit the duty ratio. For instance, with a 2-V peak voltage and a maximum duty ratio arbitrarily fixed at 80%, then the maximum excursion applied at the PWM ...

1

Parallel is fine if you use schottky diodes to OR them. If the 0.25V Vf drop is too much for application, use ideal diodes such as LM66100 (see datasheet for proper configuration when using two of them). With resepect to the voltages, you'd be much better off using components that work down to 2.5V than to use a boost (or buck) converter. With smart low-...

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