Load and regulation of LM2576 3A Adj. Power Supply

[electronion]

How much the load & line regulation of LM2576 3A adj. Power supply?
Someone who have built it please gimme more informations about it.. (maybe like its drop voltage, adding the extra protection, etc.) so I can build a good Adj. power supply with LM2576..

 

[Tahmid]

First of all, you should check the datasheet. The datasheet specifies a ±4% max variation over line and load conditions.

www.national.com/ds/LM/LM2576.pdf
**broken link removed**

 

[electronion]

Okay, I want to built a short circuit protector in the power supply..
if I used a relay controlled by mikrocontroller to avoid the short circuit beetwen my power supply an the load by switch the connection off..
what do you think? is that ok?

 

[Sajjadkhan]

If you use relay then after the short circuit your relay will open and but when it will open and your circuit detects that there is no short circuit so it will close again but actually ur circuit is still in short circuit mode so you relay will start oscillation on off on off on off and it will make noise. u need a small current circuit after the relay.
consider the following circuit, its for ur understanding only.


switch is realy ok. so if short circuits occur realy will switch to upper side and connects with the same supply but now with R1 in series. so if short circuit still occurs there will be no voltage across r2. and u can use this signal to detect short circuit.

Do one thing if u are not using any controller than connect r2 with a transistor and operate relay with it. the realy will initally be off when you power the circuit then your relay will be in upper position since there is no short circuit and r2 has signifiant voltage on it to drive transistor it will turn on the realy and you will have a connection but if even in start you short the circuit and power the circuit then transistor wont turn on so realy wont turn on and your circuit will be protected. yes it may happen then when realy will be switching then inbetween there will be no connection for transistor so it will turn off quicker and calls back the realy in that case install a capacitor parallel to r2 to hold its value at least for 10ms.

 

[electronion]

sajjadkhan, thanks for your info..

Now, I think, I will use the relay with 2 current sensors to protect the short circuit..
The first relay will switch off when short circuit condition and wait until the current sensor senses there is no more short circuit.. when there is no more short circuit, the relay will switch on.. so, the ossilation on off will not happen..