high voltage power to the micro controller problem

[sudheervemana]

Hi all,

In my application board we are using TIDSP's
TMS320LF2407A micro controller which requires 3.3v supply.we are
generating an 3.3v in the board by using an switching regulator
through 24v supply input from the external.when i am trouble shooting
the regulator,the output of the regulator which is 3.3v mistakenly
gets 24v supply . i think the controller power pins may get this 24v
,which actually should require 3.3v supply.I want to know whether my
processor is working fine or not.can any one give me your suggestions
,and also clear me how to verify my controller ,whether it is working
or not.

what are the minimum things that are required by an controller
to work,like all the power pins ,reset pin verification and external
crystal that is used to drive the internal oscillator.one more thing
is in my board all the power pins are placed with an by-pass
capasitors ,if any one of the capacitors gets failed ,the power will
go the ground ,i want to know how to find out the shorted or dead
component.please give me your valuable suggestions to find out the
problem.

With Regards,

sudheervemana.

 

[Stefan Heinzmann]

Hi all,

In my application board we are using TIDSP's
TMS320LF2407A micro controller which requires 3.3v supply.we are
generating an 3.3v in the board by using an switching regulator
through 24v supply input from the external.when i am trouble shooting
the regulator,the output of the regulator which is 3.3v mistakenly
gets 24v supply . i think the controller power pins may get this 24v
,which actually should require 3.3v supply.I want to know whether my
processor is working fine or not.can any one give me your suggestions
,and also clear me how to verify my controller ,whether it is working
or not.

If you apply 24V to the TMS320LF2407A it will die. If you have done this
while trobleshooting the regulator, you will most certainly have to
replace the controller. Depending on your circuit, it is quite likely
that other components have been damaged, too. If your prototype board is
not too valuable, it may be easier and quicker to build a new one.

Troubleshooting a regulator is best done with the real load disconnected
and replaced by a dummy load (i.e. a resistor).

what are the minimum things that are required by an controller
to work,like all the power pins ,reset pin verification and external
crystal that is used to drive the internal oscillator.one more thing
is in my board all the power pins are placed with an by-pass
capasitors ,if any one of the capacitors gets failed ,the power will
go the ground ,i want to know how to find out the shorted or dead
component.please give me your valuable suggestions to find out the
problem.

The capacitors may have failed only if their voltage rating was lower
than 25V. If that's the case, then I think it would be easiest to
replace them all, because they are cheap, and because they can fail in a
way that is not easy to measure while they are in the circuit.

But, as I said, you can expect that other components have suffered, too.
Sorry for the bad news.

 

[DJ]

If you apply 24V to the TMS320LF2407A it will die. If you have done this
while trobleshooting the regulator, you will most certainly have to
replace the controller. Depending on your circuit, it is quite likely
that other components have been damaged, too. If your prototype board is
not too valuable, it may be easier and quicker to build a new one.

Troubleshooting a regulator is best done with the real load disconnected
and replaced by a dummy load (i.e. a resistor).


The capacitors may have failed only if their voltage rating was lower
than 25V. If that's the case, then I think it would be easiest to
replace them all, because they are cheap, and because they can fail in a
way that is not easy to measure while they are in the circuit.

But, as I said, you can expect that other components have suffered, too.
Sorry for the bad news.

That's good advice. It's in the nature of prototypes that they emit smoke from
time to time.

dj

 

[Stefan Heinzmann]

On Sat, 31 Jan 2004 12:22:15 +0100, Stefan Heinzmann
That's good advice. It's in the nature of prototypes that they emit smoke from
time to time.

And, as the saying goes, once the smoke got out it is very hard to get
it back in again ;-)

 

[Jan Panteltje]

And, as the saying goes, once the smoke got out it is very hard to get
it back in again ;-)

Soon smoking prototypes in the workplace will be forbidden.

 

[Stefan Heinzmann]

Soon smoking prototypes in the workplace will be forbidden.

That is in line with a policy to get it right first time, one of our
management evergreens.

 

[John Woodgate]

I read in sci.electronics.design that Stefan Heinzmann
online.com>) about 'high voltage power to the micro controller problem',

That is in line with a policy to get it right first time, one of our
management evergreens.

But you are given only 80% of the time required to get it right. Then
you need another 80% to put right what you didn't have time to do
because of the 20% you didn't get.

 

[Stefan Heinzmann]

I read in sci.electronics.design that Stefan Heinzmann
online.com>) about 'high voltage power to the micro controller problem',



But you are given only 80% of the time required to get it right. Then
you need another 80% to put right what you didn't have time to do
because of the 20% you didn't get.

Plus, the marketing people decide half way down the line that they need
a couple of extra features they rejected originally, and that the
product is too expensive.