Likelyhood of blowing CMOS chips by applying reverse polarit

[royalmp2001]

What are the chances of detroying a CD4069 or a 7555 by applying the
power with reversed polarity.
Anyone destroyed such a device this way??

 

[John Larkin]

On 2 Sep 2005 17:06:56 -0700, "royalmp2001" <royalmp2001@hotpop.com>
wrote:

What are the chances of detroying a CD4069 or a 7555 by applying the
power with reversed polarity.

Assuming a non-wimpy power supply, 100%.

Anyone destroyed such a device this way??

That, and lots of other ways.

John

 

[Pi]

On Fri, 02 Sep 2005 20:14:02 -0700, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On 2 Sep 2005 17:06:56 -0700, "royalmp2001" <royalmp2001@hotpop.com
wrote:
What are the chances of detroying a CD4069 or a 7555 by applying the
power with reversed polarity.
Assuming a non-wimpy power supply, 100%.
Anyone destroyed such a device this way??
That, and lots of other ways.
John

Usually testing has next steps:

1 move as far away from the electronics as possible
2 turn on the power
3 do you see the light (!) ? If so, the test failed, stop it.
4 wait a minute
5 do you se smoke ? If so, the test failed, stop it.
6 do you smell anything? If so, the test failed, stop it.
7 wait a minute, then touch the eletronics, espacially the power parts
8 did you burn your fingers? If so, the test failed, stop it.
9:
You reached the end of the test. Does it actually work? If so, keep
your mouth shut to the commercial people in your company and make all
neccesary improvements before they claim the project to be finished
and make a product from your first test setup.

Pieter

 

[Don Bruder]

In article <1125706016.914026.10140@g49g2000cwa.googlegroups.com>,
"royalmp2001" <royalmp2001@hotpop.com> wrote:

What are the chances of detroying a CD4069 or a 7555 by applying the
power with reversed polarity.
Anyone destroyed such a device this way??

Quite high - Perhaps not 100%, but close enough to it for practical
purposes. I'm sure hundreds, if not thousands, of electronics tinkerers
have blown up chips (CMOS or otherwise) this way.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

 

[PeteS]

It's not just tinkerers that blow up chips that way - I have had new
units go to production (first ever run) and had parts in backwards.
With the power at corner pins, that meant the power was applied
reversed.

Fortunately, the burn marks on the PCB were not fatal to the unit
(although the misplaced components had the magic smoke released).

Cheers

PeteS