how to prevent negative voltage to enter into IC

P

ponsakthi

New Member

• Feb 13, 2009

• #1

hi all
i have a 12v to 5 v converter IC.

there are two points external to the module which are connected to 12v ic input and ground respectively.


but instead if they reverse the pins and connect 12v to ground pin and 0v to in i/p the ic burns out.


so what circuitry should ia dd on the input path of the 12v ic i/p to avoid negative voltages through it

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 13, 2009

• #2

Feed the 12V through a suitably rated rectifier diode.

 

P

ponsakthi

New Member

• Feb 13, 2009

• #3

diode will dissipate a large amount of heat .. isnt it?

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 13, 2009

• #4

ponsakthi said:

diode will dissipate a large amount of heat .. isnt it?

Click to expand...

As you've provided absolutely no details about the current required, how would we know? - but W = V x I

 

P

ponsakthi

New Member

• Feb 13, 2009

• #5

sorry the module takes 1.2 A of current

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Feb 13, 2009

• #6

Then the diode will dissipate about 0.84W, use a 3A or 5A diode you should be fine. Bear in mind as well, the regulator will dissipate less power, due to the 0.7V lower voltage supoplied to it.