Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Power supply questions

Status
Not open for further replies.

maormat4

Junior Member level 3
Joined
Mar 1, 2017
Messages
26
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
203
Hello my friends,

i have some questions (some of them are wired):
1) What is the prefferd way to work? discontinous mode or continous mode?
2) what is the different between voltage feedback and current feedback?
3) assume i have 3 power supply modules connected in parallel using oring diodes, the output voltage will be a voltage that one of the oring diodes will be reversed biased, so one module will not work?
4) If i have a battery that doesnt connected to anything, the battery have parastic resistance so she some day will discharged. but, the air have a resistance so the battery will discharge throw the air too (in a very low current)? so its mean that the battery will discharge from all the universe and she make a current to flow all over the universe (a very very small current)?
5) If i have a battery of 5V and the negitive terminal is connected to ground and the positive terminal is connected to diode chatode, and the anode of the diode is disconnected, what will be the voltage at the anode?

Thank you my friends
 

1) What is the prefferd way to work? discontinous mode or continous mode?

Continuous mode has the advantage because your inductor can be rated for a lesser saturation current. A frequent recommendation in smps is 10 percent current ripple through inductor.

Suppose your average current is 5A. In discontinuous mode your waveform crests at 10A (minimum), then drops to zero. This requires a saturation rating =10A.

On the other hand in continuous mode your waveform can range between 5A and 6A, allowing saturation rating=6A. It means your inductor can be less bulky, less expensive. Also there is the benefit of reduced stress on components.
 

...
2) what is the different between voltage feedback and current feedback?
...
Voltage feedback is basically measuring the voltage of interest (especially the output voltage) in order to control it's value to bring it back down when it exceed a setpoint or take it back up when it goes below the setpoint.

Current feedback on the other hand is measuring a current of interest, usually in the form of voltage though (you know I*R=V) to compare with a voltage set point for controlling the current. Current feedback is used in two control schemes: (i) average current mode, where the average value of current is controlled without bothering about the peaks. (ii) peak current mode, where the peak value of the current is controlled
 

5) If i have a battery of 5V and the negitive terminal is connected to ground and the positive terminal is connected to diode chatode, and the anode of the diode is disconnected, what will be the voltage at the anode?

On anode the ideal diode will be 0V between anode and Ground, becouse diode is in councluding direction.
Real diode have any small leakage current for example 2uA and it will depend on the resistance of the voltmeter that we will measure.
 

Hi,

I was curious about the diode question, so simulated it then did a breadboard version with a typical rectifier, a typical fast signal diode and what I think has to be a typical Schottky diode. I only measured voltage to ground from the anodes as that was the question.

If I can ask, why does the simulation show entirely different results to the real circuit(s)?

Also, is the Schottky leakage really that high normally, compared to the standard silicon rectifiers (or did I use a damaged diode or maybe the SIL pins affect the reading)? It seems very high, in my ignorance, i.e. the ~600mV compared to ~10mV to ~20mV for the other two.

Thanks.

disconnected diode results real and simulated.jpg
 

Air is regarded as an insulator rather than a conductor of electricity. When a lightning bolt strikes, it is electricity traveling through a path of ionized air. To make it occur requires thousands of volts.

An idle battery self-discharges internally more so than by interaction with the external universe. Electrolyte chemistry gets weaker. Terminals accumulate corrosion. Aging nicads have a tendency to develop metal whiskers (dendrites), reducing its ability to hold a charge.
 

Hi,

I was curious about the diode question, so simulated it then did a breadboard version with a typical rectifier, a typical fast signal diode and what I think has to be a typical Schottky diode. I only measured voltage to ground from the anodes as that was the question.

If I can ask, why does the simulation show entirely different results to the real circuit(s)?

Also, is the Schottky leakage really that high normally, compared to the standard silicon rectifiers (or did I use a damaged diode or maybe the SIL pins affect the reading)? It seems very high, in my ignorance, i.e. the ~600mV compared to ~10mV to ~20mV for the other two.

Thanks.

View attachment 151048

You were trying to measure leakage? That's a tricky thing to do without precision equipment (your meter has finite impedance and its own leakage).

Yes Schottky can leak like crazy which is one of their key downsides.




4) Yes the battery theoretically conducts through air and the entire universe but of course at a much much lower rate than through itself, or also probably along leakage paths along its outer surface. Lightning is formed through current going through the air slowly, then ionizing the air and then conducting very quickly.

Note that this seems silly but parasitics such as this matter. Such as the capacitance of your body building charge or causing ESD shocks
 
  • Like
Reactions: d123

    d123

    Points: 2
    Helpful Answer Positive Rating
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top