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.

Register Log in

How can get a contant and abrupt DC output?

Status
Not open for further replies.

jacobocd

Newbie level 4
Joined
Apr 4, 2011
Messages
5
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,316
Hello,

I'm designing a power supply PCB, whose input is a 28V DC, and has two outputs at 5V and 15V,DC.

I have a problem with the regulated output of 5V, because, the time to reach the 5V in the initial instant is too long (about 8ms). I want that remain the 5V close until 5V is reach at the output, then, the output will be opened.

How can do it?Are there some circuits to it?

Thanks in advance
 

Einar M

Junior Member level 3
Joined
Mar 17, 2011
Messages
31
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Location
Calif.
Activity points
1,432
Putting a MOSFET in series with the 5V and turning it on after a suitable delay could work. There would be some loss of load regulation caused by the on resistance, but if the load isn't too large it wouldn't be too bad.
 

jacobocd

Newbie level 4
Joined
Apr 4, 2011
Messages
5
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,316
Thanks,

Where can find some tipycal circuits of this type?
How is the best way to analyse the circuit?
 

Einar M

Junior Member level 3
Joined
Mar 17, 2011
Messages
31
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Location
Calif.
Activity points
1,432
It was too late last night to draw up diagram. This is what I had in mind:
C1 and R1 determine initial delay ( aprox 10 mS ). R2 controls output ramp; smaller R faster etc. Choose for best looking response. Q1 can be 2n7000 , Q2 a power FET with 10 milliohm on resistance. C2 is probably already part of reg.
As for analysis, SPICE might work. I do it in my head with help of pencil and paper.
 
Last edited:

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top