Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic 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.

How to design a power supply that change current and voltage using comparators?

Status
Not open for further replies.

wolf12

Advanced Member level 4
Joined
Mar 31, 2011
Messages
109
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Activity points
2,102
How to design a power supply that change current and voltage using comparators? About 0 to 50 volts and 0 to 3 Amperes.
I dont know how you use comparators either. A big explanation will be very helpful.
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
48,211
Helped
14,207
Reputation
28,673
Reaction score
12,903
Trophy points
1,393
Location
Bochum, Germany
Activity points
279,282
Referring to your previous thread https://www.edaboard.com/thread212949.html, you have been asking how to design a power supply. Why do you think, that comparators should be used for it? They may be possibly used for special purposes, e.g. overcurrent shutdown. But they are not substantial for power supply design.
 

wolf12

Advanced Member level 4
Joined
Mar 31, 2011
Messages
109
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Activity points
2,102
Referring to your previous thread https://www.edaboard.com/thread212949.html, you have been asking how to design a power supply. Why do you think, that comparators should be used for it? They may be possibly used for special purposes, e.g. overcurrent shutdown. But they are not substantial for power supply design.

I've heard about a feedback system, I want to make one. You monitor the output of the powersupply with a comparator, if the voltage is 5.2V and when we have adjusted it to 5V, it sees the additional 0.2V and adjusts a resistance or something to make it 5V. This is power electronics right? Can you suggest me a book or a website to learn how to do this.
 

alexan_e

Administrator
Joined
Mar 16, 2008
Messages
11,895
Helped
2,021
Reputation
4,158
Reaction score
2,031
Trophy points
1,393
Location
Greece
Activity points
64,377

polo-g40

Full Member level 2
Joined
Jan 12, 2011
Messages
143
Helped
36
Reputation
84
Reaction score
42
Trophy points
28
Location
Gone
Activity points
0
I have seen comparators used in motor control circuits for PWM power control, might be what you are thinking of for big DC supplies.
In some integrated chips I've been looking at recently, the comparators are a big part of the internal circuit diagram. In these, if the load current goes over a certain ammount and causes the voltage over a low resistance sense-resistor to go above a (set-able normally) reference voltage it will cut the current off completely until a small capacitor (value sets speed) has discharged, giving the current time to drop and then it'll try full whack again, over and over and over, kHz. They are so efficient in power electronics because the quick switching times mean there is rarely any voltage or current across the chip, just one or the other, so little power is wasted....

If you aren't worried about noise and a bit of a ripple on the output they're a good idea , they are available in various power levels depending on what you buy, all having similar characteristics. It would probably be possible do a similar idea with voltage if you can build it but I'm not 100% on the use of it that way..

Neal:)
 

FvM

Super Moderator
Staff member
Joined
Jan 22, 2008
Messages
48,211
Helped
14,207
Reputation
28,673
Reaction score
12,903
Trophy points
1,393
Location
Bochum, Germany
Activity points
279,282
I have seen comparators used in motor control circuits for PWM power control, might be what you are thinking of for big DC supplies.
The original poster has clarified in his second post, that he's looking for a basic regulated power supply. Suggesting switching mode circuits or particularly self-oscillating "hysteretic" switchers effectively means trying to run before one can walk. Don't forget, that switching mode circuits also implement a feedback structure, that can (and should) be analyzed in terms of linear control theory in a first order. You can derive important parameters like loop bandwith, characteristic frequency, phase margin, stability and transient response from a time continuous representation of the switcher circuit. Understanding the theory is however complex enough for a linear controller, I think.

The literature suggested by Alex has some good material to understand the linear regulator basics.
 

polo-g40

Full Member level 2
Joined
Jan 12, 2011
Messages
143
Helped
36
Reputation
84
Reaction score
42
Trophy points
28
Location
Gone
Activity points
0
Sorry, I was looking at the question of why they'd thought a comparator may be used, no realising I was on completely the wrong tack. Appologies the [q]I've heard about a feedback system, I want to make one.[/q] made me think was walking already, sorry.
NEal
:)

although i did think
[q] You can derive important parameters like loop bandwith, characteristic frequency, phase margin, stabilty and transient response from a time discrete representation of the switcher circuit. Understanding the theory is however complex enough for a linear controller, I think.[/q]
may be a bit forward for a "walker".
 
Last edited:

kamalavignesh

Newbie level 6
Joined
Oct 4, 2010
Messages
11
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Location
Vijayawada
Activity points
1,368
For designing power supply with voltage and current control you can use TOP switch with feedback system. The feedback system will give control signal to the control pin of top switch by which the output voltage and current is limited to set value. this page will be helpful i think http://www.powerint.com/sites/default/files/PDFFiles/der227.pdf
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top