P2 - Cool, Hot, or Wot?

Peter JakackiPeter Jakacki Posts: 7,868
edited November 17 in Propeller 2 Vote Up0Vote Down
Yeah, the P2 is a very cool chip indeed but it does not run cool. Some say it runs hot. Wot then is hot?

Let's check it out with a P2D2 that I have mounted flipped with the chip facing down and a thermocouple taped with polyimide to the rear of the pcb smack bang center of the P2 hotspot. My bench P1 reports the ambient as 26.7'C with 55% RH in still air, no fans or A/C etc.

Now I will test the P2 using a new version of TAQOZ that has VGA and a keyboard connected as well as other devices. I am mainly using two cogs, one for TAQOZ and one for 640x480x8 VGA and the TAQOZ console is switched over to VGA and keyboard displaying text and bmp graphics etc. The 12MHz clock divider is set to 1 and I am multiplying from there.
		>5 mins		FINGER		>2 mins
		NO COOLING	TOUCH		25mm FAN	NOTES
100MHZ		43'C				33'C			
120MHZ		45'C				36'C		slow to heat		
180MHZ		54'C    	47'C		39'C
240MHZ		59'C		50'C		40'C
300MHZ		63'C		52'C		43'C
324MHZ		66'C		55'C		44'C		burns my finger

So I wouldn't operate the P2 at 300MHz without cooling unless it was used indoors where the ambient is low but by the same token even a tiny bit of heatsinking with my finger will immediately cool it and even using a very small 25mm fan will prevent it from ever feeling hot to the touch even at 324MHz. When I get some new chips during the week I will check one out on the current P2D2 before deciding if I want to add extra layers. My opinion is that I don't need extra thermal layers, but if run at 300MHz or so I just need a tiny bit of air flow or place the back of the P2D2 against a metal case.

BTW - activating all the cogs doesn't really seem to make much difference.




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Comments

  • 64 Comments sorted by Date Added Votes
  • Clock LoopClock Loop Posts: 1,564
    edited November 17 Vote Up0Vote Down
    So I wouldn't operate the P2 at 300MHz without cooling.

    Almost all kits for the raspberrypis, now have heatsinks included, and their cases have fans now too.
    ...


    Nuthin wrong with that. Heck, take advantage of the pi form factor/pinout/usbpower methods, etc... and use them with the p2, and boards.... and you have cases and addon-"hats", power supplies, and heatsink kits all ready to rebrand. ;D

    1. Silicon gel filled square. <---2.Sonics(ultra even). 3.Lazers. 4. ?
    https://hackaday.io/project/162734-a-trillion-year-clock
    54 propeller chips were connected to One, to rule them all....
    https://forums.parallax.com/discussion/127983/55-parallax-propeller-s-parallells-processing-of-permanent-perturbations/p1
  • If we don't get clock on pins, guess I'll need 300 MHz to do digital 1080p60...
    This data makes it look like maybe a nice heat sink would be good enough.
    With a fan if enclosed...
    Prop Info and Apps: http://www.rayslogic.com/
  • Thanks for sharing this data Peter! The numbers don't look too bad at all. I bet a decent heat sink would be enough for most use cases.
    I think a fan would only be "required" if you are doing the extreme overclock or have it enclosed in a small case that doesn't have much room for normal convection.
  • What I noticed is that even at 148.5MHz it gets hot and after a while the VGA starts to get fuzzy. But it may not necessarily be the P2 causing the problem although touching both sides of the pcb at the chip settles it down.
    I haven't had time to test this thoroughly yet. Still working on the VGA and streamer. :smiley:
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Peter, I would still go with a 2 layer pcb with std copper. We want to see what this can do. Chips board has the copper and 4 layer alternative for comparison.
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Peter JakackiPeter Jakacki Posts: 7,868
    edited November 17 Vote Up0Vote Down
    Although I've been using a clock divide by 12 I thought I'd work with multiplying the 12MHz instead this time. When I went to 96MHz the LCD monitor started to jitter and this could have been an autoset problem but rather than hit the autoset button I switched back to a 1MHZx100 to get 100MHz and the jitter was gone. If only we had kept those analog monitors :)

    These tests were mainly to confirm "wot hot is" since you never actually measured it except with your finger :)

    BTW, I start up with black text on a white background. It helps your monitor's autoset if you have a non-black background, especially at the edges.

    Tachyon Forth - compact, fast, forthwright and interactive
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  • Although it seems super hot to flesh, 60C isn't actually all that hot for electronics. We expect them to survive soldering after all.
  • Lol, I still have my good analog gear.

    Added digital, not replace.
    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
    Parallax colors simplified: https://forums.parallax.com/discussion/123709/commented-graphics-demo-spin<br>
  • localroger wrote: »
    Although it seems super hot to flesh, 60C isn't actually all that hot for electronics. We expect them to survive soldering after all.

    True, but that is once-only.

    Temperature does affect Analog operation, and it does affect reliability.
    General industry claims of 10~15°C elevation halving expected life, and thermal cycling over full range reducing lifetimes by 8x, show that °C is the enemy of reliability.

  • Cluso99 wrote: »
    What I noticed is that even at 148.5MHz it gets hot and after a while the VGA starts to get fuzzy. But it may not necessarily be the P2 causing the problem although touching both sides of the pcb at the chip settles it down.

    ? fuzzy ?
    Can you expand ? Do both your working monitors show the same effect ? Is that over whole display area ?
    Maybe the DAC speed degrades with temperature, which would give a loss of focus type effect.

  • Cluso99 wrote: »
    Peter, I would still go with a 2 layer pcb with std copper. We want to see what this can do. Chips board has the copper and 4 layer alternative for comparison.

    There are already P2D2 with 2 layers, for 2 layer testing.

    To me it makes more sense to next do a 4 layer P2D2, with any 'free' copper added. eg pcbway offers 1.5oz inner layers for no extra $
    You can still use Chip's board for larger area and thicker copper comparisons.
  • RaymanRayman Posts: 8,883
    edited November 18 Vote Up0Vote Down
    Was just thinking that I'll make the area under the P2 free of solder mask.
    I have a feeling solder mask is not a good thermal conductor...

    Then, I'll see about silver pasting on a heat sink.
    Prop Info and Apps: http://www.rayslogic.com/
  • I wouldn't worry too much about the solder mask, its pretty thin

    There are some figures here for it
    https://www.intersil.com/content/dam/Intersil/whitepapers/power-module/carry-heat-away-from-power-module.pdf

    While its a whole lot thermally conductive compared to the copper layer beneath it, 0.2 C per watt is only going to add ~ half a degree to the overall temp rise, and thats based on 1 square inch rather than the 2 or more we're talking about
  • Rayman wrote: »
    Was just thinking that I'll make the area under the P2 free of solder mask.
    I have a feeling solder mask is not a good thermal conductor...

    Then, I'll see about silver pasting on a heat sink.

    There are also some solder-able small heatsinks that could suit P2, and for those bare copper would help.

    I'm not sure which is best for simple radiation, exposed PCB, or black resist ?
  • We need some of this amazing black paint this guy developed:

  • I loved that video.
    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
    Parallax colors simplified: https://forums.parallax.com/discussion/123709/commented-graphics-demo-spin<br>
  • If I squeeze my finger and thumb on the prop chip and back of pcb, I cool the P2 and pcb, and the display comes good.
    I am only at 148.5MHz so there seems to be a heat problem here.
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Peter JakackiPeter Jakacki Posts: 7,868
    edited November 18 Vote Up0Vote Down
    Cluso99 wrote: »
    If I squeeze my finger and thumb on the prop chip and back of pcb, I cool the P2 and pcb, and the display comes good.
    I am only at 148.5MHz so there seems to be a heat problem here.

    Strange, can you measure the actual temperature then. This is my clock header I use:
    con
    XIN		= 12_000_000
    CPUHZ		= 324_000_000		' desired CPU clock frequency'
    XIDIV		= 1			' crystal/osc input divider'
    CLKMUL		= CPUHZ/(XIN/XIDIV)
    CLKCFG		= 1<<24+(XIDIV-1)<<18+(CLKMUL-1)<<8+%1111_11_00
    

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  • I am dividing by 24 then multiplying by 297 to get 148.5MHz

    My temp probes are somewhere still in boxes after the last move. Insufficient time to unpack atm.

    I'll post the latest code as soon as I complete the latest tidy-up.
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Heat is definitely an aggravating factor with the P2. I can seal a P1 (e.g. FLiP module) in a small plastic case without ventilation -- no problem. Such will not be possible with the P2, unfortunately. This will limit its application in cases where NEMA 4X enclosures are mandated.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Heat is definitely an aggravating factor with the P2. I can seal a P1 (e.g. FLiP module) in a small plastic case without ventilation -- no problem. Such will not be possible with the P2, unfortunately. This will limit its application in cases where NEMA 4X enclosures are mandated.
    Quite a sweeping claim, yet not supported by the NEMA 4X enclosures google finds ?
    P2 is not dissipating kilowatts, but a 'small plastic case' is probably off the table, and not likely with the larger package anyway.

  • Heat is definitely an aggravating factor with the P2. I can seal a P1 (e.g. FLiP module) in a small plastic case without ventilation -- no problem. Such will not be possible with the P2, unfortunately. This will limit its application in cases where NEMA 4X enclosures are mandated.

    -Phil

    The simple trick is to move the air with a decent fan. The fan can be tiny, it just has to move the air.

    You can still have a fully sealed, even IP68 stainless steel enclosure, so long as you circulate the air within. It really isn't a big problem (based on a few decades making products typically around 10~18W dissipation).

    Remember we're running torture tests to push the limits. What current would a P1 running 8 cog torture test draw at 100 MHz? If someone has some P1 torture test code, we can test a FLIP side by side, MIPs for MIPs, with the thermal camera.
  • Avoid fans, they break down. Just build it with a heat sink.

    Money is a placeholder for cooperation
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,093
    edited November 18 Vote Up0Vote Down
    The trick is to remove the heat from the box, not just blow it around inside. If the box is sealed, a Peltier cell with fins inside and outside the box might do the trick. OTOH, if the box is big enough (i.e. has enough surface area), it can radiate enough heat on its own.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Blowing it around does transfer the heat to the box and from the box to the outside environment.
    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
    Parallax colors simplified: https://forums.parallax.com/discussion/123709/commented-graphics-demo-spin<br>
  • Right, my point is that moving air is the way to achieve Nema 4X or IP68, nothing special required on the outside surface

    On the fans thing, use a quality fan with a decent L10 rating, not a cheap CPU cooler designed to give you an upgrade every 3 years. From the other thread where we dealt with same:-
    If you look at the specs on quality (eg) ebm papst fans you'll see many models that have L10 figures well over 10 years. If you go by IPC L10 figures, many approach 20 years, and L10 means 90% of them continue operating past that point.

  • Was mine too. Even passive convection in the box can work.
    Do not taunt Happy Fun Ball! @opengeekorg ---> Be Excellent To One Another SKYPE = acuity_doug
    Parallax colors simplified: https://forums.parallax.com/discussion/123709/commented-graphics-demo-spin<br>
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,093
    edited November 18 Vote Up0Vote Down
    potatohead wrote:
    Even passive convection in the box can work.
    ... depending on the size of the box.

    I recently did an LED-string special effect (shooting star, aurora) for a school play. I used a FLiP module (one of Parallax's best products!) and had no concerns about heat, even in the small, plastic single-gang junction box I designed the driver PCB around. What I hadn't planned on was the 1/8th-brick 24V-5V DC-DC converter plugged into the same PCB getting hot, given its 90+% efficiency rating. But get hot it does, even when idling, even with a heatsink. So I had to drill 1" holes in the box, above and below the converter and cover them with screen wire to keep the bugs out. That was enough to keep things relatively cool. But there's no way that such a small box -- even a metal one -- could have radiated the heat generated therein.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • What was your box size, Phil?

    Presumably bigger than the 1" holes...
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,093
    edited November 18 Vote Up0Vote Down
    Single-gang outlet box with fittings for conduit:

    Message_1538101362990.jpg

    -Phil
    2560 x 1440 - 1M
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
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