Author Topic: IC Protection Circuit required  (Read 3554 times)

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Offline RatfinkTopic starter

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IC Protection Circuit required
« on: April 05, 2007, 07:29:42 AM »
I've manage to fry a very expensive chip 300 pounds  :-[

As i've inherited the project i assumed the power protection circuit was good anywayz heres what we have:

Were using a 7.2V 1900mAh battery which powers up a FPGA and DSP board
The DSP board requires about 5v and 600mA (The chip is on a F2812 eZdSP board)
The FPGA requires 5.5V and 600mA

Currenty they are wired in paralell as follows:
http://img242.imageshack.us/my.php?image=circuitbg7.jpg

We need to make sure there is a constant 5V supply and 600 mA current and the DSP can draw more current when required. The DSP kept switching on and off till it burnt out.

When investigating we found the Voltage Regulator was not stepping downt he voltage were assuming there is no current protection in the setup in the diagram above.

Can anyone suggest how we can protect our expensive chips in future?

Offline ed1380

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Re: IC Protection Circuit required
« Reply #1 on: April 05, 2007, 07:32:53 AM »
« Last Edit: April 05, 2007, 07:35:31 AM by ed1380 »
Problems making the $50 robot circuit board?
click here. http://www.societyofrobots.com/robotforum/index.php?topic=3292.msg25198#msg25198

Offline RatfinkTopic starter

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Re: IC Protection Circuit required
« Reply #2 on: April 05, 2007, 08:19:16 AM »
We have a L7805c its not currently setup as a switching regulator it says on the first link you have there it provides a 3A output current how do we reduce that down to 600mA

Offline ed1380

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Re: IC Protection Circuit required
« Reply #3 on: April 05, 2007, 12:59:31 PM »
Thats the max output current.
« Last Edit: April 05, 2007, 08:32:41 PM by ed1380 »
Problems making the $50 robot circuit board?
click here. http://www.societyofrobots.com/robotforum/index.php?topic=3292.msg25198#msg25198

Offline dunk

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Re: IC Protection Circuit required
« Reply #4 on: April 05, 2007, 03:33:55 PM »
hi Ratfink,
as ed1380 points out,
as long as you have the voltages correct there should be no need to regulate the current.
the chip *should* only draw what it needs.

dunk.

 


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