LPC1778 stops running around 60C ambient temperature.

[ericsprengle]

Using the LPC1778, and have noticed on some of the boards the LPC1778 stops running when the ambient temperature gets around 60C, have even see one stop running at 55C. Have been able to reproduce failure on returned units by putting board inside chamber and running up to 60C. Failure does not occur on all boards. Some can run at 60C for more than 24 hours with no issue, others have even been run up to 70C and still no failure. The ones that do fail, can fail within 20-30 minutes of the chamber reaching 60C, others might run for a few hours at 60C before failure. They are able to start running again by applying a reset, but if they are still at the higher temp, they will just stop running again. Datasheet says operating temp is up to 85C so surprised that we are seeing this issues 25C below the max temp spec. We are running the core clock at 120MHz. We have a "heartbeat" LED connected to the LPC1778 that the LPC toggles on and off when it is running, when the LPC fails at higher temp the LED stops blinking, and is either stuck on or off. Also, ethernet communication cuts out, when failure occurs.

[Rikard]

Hi,

we also have an issue with units (Freescale Vybrid MVF61NN151CMK50) that stops running at high temperatures, i.e.+ 60° C.

If we connect to the UART interface, the units works just fine at the high temperatures, but it will stop working if we try to boot the unit without a cable connected to the UART interface.

Any help solving this issue is highly appreciated.

Regards,

Rikard

[repoxm]

Good morning,

also in our company same problem on LPC2366. It seems due to heat, and it seems solved moving MAMTIM from 03 to 04. Clock frequency is actually 72MHz. Do you think this solution safely solves the issue? Is there an official explanation of this issue from NXP? Thank you for confirmation. Regards.

[bobgudgel]

Yes, this does fix the issue of the processor stopping at lower than maximum specified temperatures.

It has worked for two of us at least.

boB

[bobgudgel]

Our company has been having this same problem with the LPC2366.  I do not see these same

register when searching my project files.  Could my heat issue also be from

FLASHTIM bit field in FLASHCFG register is marginal  ??

Eric, did changing that register actually cure/fix your heat problem ?  we also use a similar Cortex M-3 part but have not seen heat issues with those yet.  Only the LPC2366 but it is extremely frustrating and costs a lot of $$$ in production

changing parts.

Thanks,

boB

[bobgudgel]

I am going to try raising my value  in  MAMTIM which is now set to 3.

If this is the fix, then this topic may have saved our product.

Will reply later with the results.

boB

[bobgudgel]

Changed MAMTIM from 03 to 04 and it appears to have fixed the problem with crashing due to heat. Same as Eric's.

Wish I would have seen this right the answer from Dezheng !

Also, when we sent our pulled parts to NXP in California, they tested them and said they worked up to high temperatures.

Wish they could have mentioned to try changing the number of wait states for our LPC2366 parts !

Thanks for this post.

boB

[billfleming]

Please see our uEZ SW 2.08 for a PLL reference for LPC1788. (At the very least it is similar to LPC1778)

uEZ download | SourceForge.net 

In uEZ\Source\Processor\NXP\LPC17xx_40xx\LPC17xx_40xx_PLL.c we setup the PLL using a 12MHz crystal.

We also use USB, Ethernet, NOR Flash, and SDRAM.

We have tested multiple devices using LPC1788 and LPC4088 over temp with no issues using this PLL code.

Also we have similar PLL examples for LPC1756 and LPC1768 in the respective folder.

Bill

[Dezheng_Tang · Accepted solution]

Maybe FLASHTIM bit field in FLASHCFG register is marginal, make sure it's set to 5 or "safe" for all conditions.

[Hui_Ma]

Hi,

Could you provide the LPC1778 related clock configuration?

If LPC1778 use the external crystal clock as clock source?

Could you check if the system clock is still there when chip falis (check the CLKOUT pin output signal)?

Thank you .

Have a great day,
Ma Hui

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