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.

Register Log in

How to make a power input protection ?

Status
Not open for further replies.
A

ahgu

Full Member level 3
Joined
Jun 19, 2001
Messages
172
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,298
Activity points
1,552
Re: power input protection

I have power input that goes into the LDO.
I want to make sure the circuit does not go bad if somebody plug in 15 volts, or negative voltage?

What do I have put in the front of the circuit to make sure of that?
I thought about zener, But I guess I need a big zener. I don't want to put a fuse. it is too big.

thanks
ahgu

Added after 43 minutes:

Normal power input is 6.5VDC. I want make sure the circuit does not get blown when user put in like 24v and negatieve voltage.
 

power input protection

Ususally, I will put a diode in series to the positive supply in order to prevent a reverse polarity.
 

Re: power input protection

In addition to the reverse polarity diode you can use a PolySwitch for over-current protection in combination with a transient voltage suppressor (instead of a zener diode) rated for 7.5V or higher..
 

Re: power input protection

You might try:

1) series self resetting fuse (Raychem Polyswitch)
2) shunted by a power zener
3) series schottky diode

Fuse (1) opens if Zener (2) voltage reached or reversed voltage. Schottky diode (3) protects LDO circuit from small reversed voltage (~ -1 volt) if negative voltage is applied.

Take a look at http://www.circuitprotection.com
 

Re: power input protection

can I use a polyswitch that is rate for 60V 0.2amp?

even though my voltage is arround 7v? but I don't want the current to go over 0.2 amp? I guess I don't undertand the voltage rating, does it matter? or just don't exceed that so it does not break the polyswitch?
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top