3 hardware related questions.

Hi to all:

I hope that someone can help me with some of these Mini2440 related
questions:

1. What is the max current you can drain from the 3.3V suply in CON4?. I
understand there is a single LM1117-33 regulator (Max 800mA) on the
Mini2440, and it has to serve the internal circuitry, so I don´t know how
much of its capacity remains able to be drained form the board. I need to
connect a device that has a supply current of 50mA idle and 150 max at
times.

2. Is there a speaker with the impedance so high that you can connect it
directly to the audio output (as it were an earphone)?. Somebody knows
where to find online a cell-phone-like speaker?.

3. It is safe (from the termal point of view) to let the the board on 7/24
in a enclosure without forcing the air out (putting a fan). Any
experiences?

Thanks for reading and best redgards.

I have found online sites for purchasing cell phone internal speakers, but
none of these give technical info, or the impedance for these speaker:

http://www.cs-tele.com/mobile-phone-spare-parts/speaker.htm

Anyone?

1. Other then talking to the hardware designer the only way to find out is
to put a current measuring instrument in series with the output of that
supply and then measure it under all operating conditions, ie peripherals
all functioning or not as your case demands.

If you had a thermal camera or well calibrated finger you could add the
extra load and see how the temperature of the regulator chip behaves. If
the chip is damaged its output SHOULD go to zero and therefore not blow up
whatever it is supplying.

2.

3. The board is consuming roughly 5V at .6A or 3Watts.  Whether or not the
board would survive depends on ambient temperature, how well that heat can
reach the outside surface of the enclosure and how well it dissipates that
heat.  We spend a large amount of our design cycle time temperature testing
stuff, mainly to meet regulatory requirements.  But, also to hopefully give
the customer a product that will last 10+ years. 


What are your goals?

Dear davef. Thanks for your response.

We hope our Mini2440 based device, can last at least for 5 years or beyond.
My main concern regarding temperature is that normaly We make a sealed (to
protect from the dust), plastic enclosure, what is not good to transpórt
internall heat to the outside. It would be very usefull if you could give
us a general description of how your design takes the heat to the surface.

Thanks in advance and best regards.

Our product has to get rid of enough heat, >50Watts, at a ambient
temperature of 60C, for a 1minute in 4 minute duty cycle and keep component
(and solder joint) temperature below 100-120C.

Think these are inappropriate goals for you.  I was just trying to
highlight the issues you face.

Areas to research:
- reduce power consumption as much as possible
- investigate the thermal resistance of materials that you would make the
case out of
- the environment, ie is it handheld, ambient temperature range
- determine max temp ratings of all components used
- FEA analysis of mechanical design 
- etc and etc

Or a thermal camera and identify the hot-spots and then come up with a plan
to deal with them.

Is this for a one-off or high volume production?

I have bought the mini 2440 board.I am working on simulation as a part of
academic project. Please mail me a sample code "to send a rgb data from the
microcontroller to the touch screeen LCD" without any embedded operating
system[example as shown in the attachment].

Totally off-topic.

Start a new one or you miss out on answers from "software" people.  Which
is what you really want!

Dave

@kumaraswamy:
Here is the forum for your question: http://www.friendlyarm.net/forum/6
and there are also examples in the download section 2440test and uCos2.

Hello davef.

Our total power consumption is going to be a little more than 4 watts
(including the Mini board and the attached module) with an ambient
temperature of no more than 40C. Thus our requeriments are fairly less
demanding than yours.

Our product is not a high volume product (about 10 units/month).

Ferite,

I would suggest building a representive enclosure, set the unit in an
temperature chamber at 40C with probes on some key components and running a
few tests.

Now finding the key components:

I would use my finger or temperature probe and try to determine the hottest
components at room temperature and no enclosure.

Then attached probes to those parts put the mini2440 into the enclosure and
the temperature chamber and see how hot they get.

Then talk to Samsung or the maker of the hottest parts and get their
suggestions on expected life.  If anything gets above 100C report back as
that opens up other issues to do with solder joint reliability.

Good luck,
Dave

Thanks for your valuable advice. We will follow this approach to get one
enclosure thermally safe.

thanks for this information.