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What is the normal temp of the sx key? — Parallax Forums

What is the normal temp of the sx key?

Clock LoopClock Loop Posts: 2,069
edited 2006-01-21 01:36 in General Discussion
Ever since my sx key arrived, I immediately noticed it gets quite hot when powered. I run it at 4mhz using the sx key internal oscillator.

I ordered the sx-tech tool kit pro, and am powering the board with 7.5volts of regulated power, which is regulated by the tech boards regulator to 5v.

I have also noticed that multiple times when I program the sx chip the progress bar will stop, and the sx-key program locks up.

The sx-key program also locks up while trying to run DEBUG for longer than 1 minute, at the fastest walk speed. Shouldn't the sx-key run untill I stop it? I have never gotten the sx-key to run on walk mode for more than 1 minute (in fastest mode)

I disabled FIFO and that didn't change anything. If I try to change the com port settings, the sx-key software changes it back to what it wants.

I am using SX-Key v 3.10 and Rev F...

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Meh. Nothing here, move along.

Comments

  • Clock LoopClock Loop Posts: 2,069
    edited 2006-01-15 08:17
    Nevermind, my problem was that I was developing and programming with the sx-key on a laptop computer that has a pentium II- 100mhz with only 64 megs of ram.

    After I tried the same on a P4-3.2 ghz with 1 gig of ram, no issues, debuger still running, has been for over 15 minutes.

    I even checked the software install by copying the SX-key folder from my laptop to my pc. So its the same exact one.

    Of all things I didn't think the laptops limited RAM and speed would affect it. I guess stuff like this demands more cpu power/ram than I realized. Soon I will be adding 128meg of ram to the laptop so hopefully this will help.

    Still tho, the question about the SX-keys temp... normal for it to be hot to the touch? (ALMOST too hot to touch)

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    Meh. Nothing here, move along.
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-01-15 10:02
    BPM,

    no, the SX-Key should not get hot. If yoou look at the small board, you will notice that it is crowded with a lot of components. The largest one is the SX 20. Is it this chip that gets hot, or anything else?

    I think you better contact Parallax Tech Support on that matter.

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    Greetings from Germany,

    G
  • Clock LoopClock Loop Posts: 2,069
    edited 2006-01-15 23:21
    Yes, its actually only the SX20 that seems to be getting hot. I will measure the max ma draw of my sxkey and post it here.

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    Meh. Nothing here, move along.
  • Clock LoopClock Loop Posts: 2,069
    edited 2006-01-15 23:29
    MY sx-key is sinking 67.3ma to ground thru its VSS pin. This is at idle state. (before programming)

    During programming for debug it peaks at 81.6ma for the entire programming duration and then drops to 61.6ma at debug idle state.

    It floats at 63.7ma durning the fastest debug walk.
    The sx-key is sourcing (or pulling from VDD) 67.3 in its idle state. (before programming)

    During programming for debug it peaks at 82.0ma for the entire programming duration and then drops to 61.7ma at debug idle state.

    Again, it floats at 63.7ma durning the fastest debug walk.




    Also when I look at some of the chips, it looks like the clear plastic protective cover around the sx-key has melted a bit on a few of the chips.

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    Meh. Nothing here, move along.

    Post Edited (BPM) : 1/15/2006 11:38:05 PM GMT
  • william chanwilliam chan Posts: 1,326
    edited 2006-01-16 20:31
    Seems like current issue in SX-Key where if you plug in the SX-Key without 1st switching off power to the board,
    the SX-Key might go into a high current mode. ( more than 150 mA).

    Bean can testify to this, he had one dead SX-Key due to this.

    When the SX-Key goes into high current mode, programming will fail with the message unable to detect SX-Key.

    If you get such a message, it is advisable to quickly switch off the power and try again a few seconds later.

    I noticed that the current draw of the SX-Key (when in high current mode) is so large that the un-regulated voltage ( before going into the regulator ) drops in such a way that you can clearly see the Power LED dim significantly. ( its a good idea to have a power led ). This dimming is also a good warning indication to quickly switch off power.

    I also noticed that if the regulator and filtering capacitors are very near the SX, ( for example in a very small board),
    the SX-Key is unlikely to latch into this "high current mode" even if power is not switched off when plugging in the SX-Key.

    This issue exists in both SX-Key revision E and revision F.
    I hope the new USB SX-Key will have a current limiter......
  • Clock LoopClock Loop Posts: 2,069
    edited 2006-01-16 23:52
    I always unplug the power to my tech board before plugging anything into or unpluggin anything. Thats definelty not my problem.

    So no one knows what the normal ma draw on the sx-key is?

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    Meh. Nothing here, move along.
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-01-17 15:09
    Well, it seems to me that the 'current draw' is in the ball park [noparse][[/noparse]Guenther has produced some charts related to supply voltage and clock freq] , but the operating temperature should not melt the shrink wrap.

    Honestly, I haven't used my SX-KEY enough to notice any change in the covering. But asking if that is normal in the life of one is a better indicator of trouble.

    There is always a possiblity that some small variation in manufature [noparse][[/noparse]including the board, not just the SX's IC] could be creating a localized hot spot.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-01-17 16:27
    BPM,

    I just took an SX-Tech board without an SX, or the SX-Key installed. Powered from a 12V switched 1A wall-wart supply, I measured a supply current of 21.5 mA. I assume, most of it flows through the green LED, and a minor part may be "eaten" by the voltage regulator.

    Next, I plugged in the SX-Key (simply in idle mode), and the supply current went up to 85 mA, so an additional current of 63.5 mA. Most of it should be "consumed" by the SX-Key, and another smaller part by the regulator. This should give you a rough value. To measure the true current into the SX-Key, I would have to cut the trace at the Vdd pin. For now, I refrained from diong it smile.gif .

    So the values I have measured are pretty close to yours, although my SX-Key does not get hot - just a little warm.

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    Greetings from Germany,

    G
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2006-01-19 12:49
    How about using a thermometer? Real data goes a long way.

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    "When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

    ······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2006-01-19 17:16
    Well, due to some practical experience I could gather in my engineering life, my thermometer is my finger smile.gif . As long as I can touch something without feeling burned, it is below 75° C. Maybe, I should re-consider this because since a while, I watch cooking shows in TV, and noticed that the professional Chefs simply use their fingers to turn around a piece of meat in the pan. As I like cooking myself, I tried the same, and felt burned in the beginning but in the meantime, my fingers got used to higher temperatures. So I possibly need a re-calibration. On the other hand, modern semiconductors can stand higher termperatures than the good old Germanium components. So possibly the increased "is-hot" threshold in my fingers exactly matches the progress of modern components.

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    Greetings from Germany,

    Günther
  • Clock LoopClock Loop Posts: 2,069
    edited 2006-01-21 01:36
    Parallax is sending me a replacement. They said they would test the sx-key and determine if I broke it, and then charge me 1/2 cost of the sx-key if they think I did it. That kinda frieked me out because not only did I just get it, but I haven't done anything with it, but hook it up to the SX-TECH board that it came with. And the SX chips it came with. If I were to fry anything, it would be the sx chip, not the key. So if it was broken, or something, then it arrived to me that way... :/

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    Meh. Nothing here, move along.
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