BS2px Gets Hot
herold
Posts: 66
I just got my BS2px and I am running it in the board of education (USB). The chip gets very hot, so hot you cannot touch it. Is that normal?
Thomas
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Thomas
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Comments
·· The chip feels hot enough to burn?· You can't touch it at all?· Does it run?· That is, if you leave it on for 10 minutes can the Stamp Editor still download code to it?
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Chris Savage
Parallax Tech Support
csavage@parallax.com
It's very hot, but after 20 minutes running everthing runs ok. Downloading ok too. My questions just was to confirm that the chip get hot as it is high takted.
My suggestion is to disconnect·ALL external connections to the inputs and outputs.
Program the device to make all outputs low (or high) and see if it still gets hot? Post Edited (KenM) : 5/27/2005 11:52:05 PM GMT
·· Are you running it with anything connected to the pins?· If so, what?· That fact that it's running after 20 minutes means that it's probably fine.· If there was a problem, you'd most liekly know by then.· Be sure to observe the maximum source/sink currents on the I/O pins, as well as the on-board regulator, if in use.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
Just my $0.02
Chris
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··········· What voltage are you running the Bs2px at? Like the BS2sx this unit is suggested to be powered at 5.5 to 7vdc any level above that will cause the unit to run hot due to the amount of current it uses.
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Stephen Swanson
Technical Support
Parallax, Inc.
sswanson@parallax.com
Would you like me to send the chip back to Parallax for an exchange. I have ny doubts that it will run over a few hours.
And yes, I would say my fingers are 'normal'.
Post Edited (herold) : 5/26/2005 6:46:13 PM GMT
··········· The unit will run hot at 9vdc, but will run fine as long as the current draw on the stamps VDD pin is not exceeded. The voltage regulator on the Bs2px has, a built in protection for over current and voltage. If the unit is running to hot for your application then you might want to use a different supply. Also the 9vdc power supply we carry is a unregulated supply so on a no or low loaded circuit ·the voltage output can be as high as 12vdc~.
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Stephen Swanson
Technical Support
Parallax, Inc.
sswanson@parallax.com
I am curious, exactly what component gets hot, and can you place an amp meter in series with the input voltage?
Another thought just came to mind......Do you have any unused pins connected to nothing? One possibility is pins configured as inputs without pull-up or pull-down resistors can make the chip run hot, and I will not go into why at this time. We call these "floating" pins.
If there are any unsued pins configure them for internal pull-up and recheck.
herold,
When you say "the main chip #2 in the pictiure" I assume that to be the part labled "B"
If the voltage regulator is working properly, that component (B) should run the same temperature regardless of the·input to the voltage regulator.
The regulator input could be·7 volts,·10 volts,·or 12 volts......the output of the regulator, and input to "B" should be 5 volts, regardless of the input voltages just mentioned.
As long as the input to "B" is 5 volts, the·only variables that will affect the temperature is the clock speed (does not change) the work that "B" is doing (how often things are being switched on and off),·the load current being sourced or sinked (edit>) and or unused floating inputs. P (heat)·= I*E....E should be constant....5 volts.
Higher input voltages to the regulator, for the·same current consumption will however cause the voltage regulator temperature to increase, but not affect the SX chip (B), again, assuming the chip input is 5 volts, and you are running the exact same program (same current consumption).
Your result of running "not as hot" with a 6 volts supply is interesting.
I don't recommend doing this unless you are very confident not to short pins.....but do you know what the voltage input is to "B" using your new 6 volt power supply versus your old power supply?
Ken
Post Edited (KenM) : 5/27/2005 11:57:27 PM GMT
This is a long shot, but if you have a magnifying glass look at the SX48 and can you see any solder balls between the pins? Again, this is a longshot....I have known Parallax products to be of extreemely high quality.
As an alternative to the above, if you make all pins outputs, and drive them high, will a DVOM indicate all pins (P0 ~ P15) are indeed 5 volts?
With an SX28 I have purposely made an output high and shorted it to ground.
Two things were noted
If I remember though, didn't you say the power supply was using about 70mA in this mode? If so, unlikely a short, but worth a look at this point.
However, this test really isn't a valid comparison for a BS2Px, because now I realize the BS2Px does not run at the same clock speed as a BS2P, it runs faster, so in theory, the BS2Px under these same condition should run warmer.
Anyway,·for what is is worth.... total current consumption was running about 80 mA, the ambient temperature was 77 deg F, the surface temp of the SX48 reached a maximum of 89.5 deg F.