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Creating a Prototype? Consider This

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Max The Magnificent
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Poised to throw the power switch
Max The Magnificent   7/17/2013 5:28:57 PM
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Hi Adam -- I agree that the seconds leading up to your throwing the power switch on a prototype board for the first time are jolly exciting.

In the past, when clock speeds were a lot lower and we were working with dual-in-line (DIL) packages, we used to sucket all the ICs on our prototypes. Before we first powered up the board, we pulled all of the ICs out so we could first check that there were no shorts, and then check that all of the IC sockets had power and ground on the appropriate pins.

It's a lot trickier these days with high clock speeds and surface mount technology, when the prototype board has all the ICs soldered down...

Adam-Taylor
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Re: Poised to throw the power switch
Adam-Taylor   7/18/2013 3:45:06 PM
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Max,

You can do this with two wire points on voltage rail which allows isolation of the power from expensive components unitl it has been powered and verified.

Adam

betajet
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Re: Poised to throw the power switch
betajet   7/18/2013 5:05:04 PM
First, I always check that chip power and ground are wired up correctly using an unassembled "solder sample" board and a continuity checker.  Beep... beep... Drives your cow-orkers crazy.


Next, I first power up the board using a lab power supply with current limit.  I slowly raise the voltage to make sure the board is behaving itself.

Lesson learned: if you have one of those packages with a large ground pad under it, expect that the fab house forgot to put the solder paste under it when making your prototypes.  Also, if possible bring the ground pad artwork out from under the chip so you can heat up the pad if you need to resolder the chip.

Max The Magnificent
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Re: Poised to throw the power switch
Max The Magnificent   7/18/2013 5:28:36 PM
@betajet: Lesson learned: if you have one of those packages with a large ground pad under it, expect that the fab house forgot to put the solder paste under it when making your prototypes.

LOL (but with a sad wry smile)

Sheetal.Pandey
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Re: Poised to throw the power switch
Sheetal.Pandey   7/19/2013 1:07:37 PM
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This reminds me of Board bring up times. Everytime a new board was populated and made ready to test, there was a new problem seen. Processor with BGA package have their own issues. Its so helpful to add as many test points when you are making those initial prototypes. EMI/EMC issues take their own time to solve. But I would say its fun, staying awake long nights sometimes no sleep till the first board is up and repeating on few boards. Its like passing some exam.

elctrnx_lyf
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Re: Poised to throw the power switch
elctrnx_lyf   7/20/2013 4:39:52 AM
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Board bring up is definitely very interesting part of the board testing. Few minor problems some times give a really long trouble and a big issues can be found easily. Overall the next interesting is the reliability testing for any product.

JanineLove
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Frankenstein Test Equipment
JanineLove   7/23/2013 9:28:01 AM
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"Will you need any special test equipment? When will it become available to you?" Anyone ever get to the point where you are ready to test, but the equipment you needed wasn't ready for you? What did you do to punt?

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