TMS320F2800156-Q1: Missing Clock Detection

Hi,

youjun zhang said:

Why is this circuit so easily damaged?

How do you know if the circuit is damaged ? Also what do you mean by circuit ? MCU ? or Product ?

youjun zhang said:

encountered several defective products

Again these statements don't help us know the issue or debug the cause. I would suggest you let us know what you found exactly, as in how did you confirm there is fault in MCD ?

To clarify: Missing clock detection is a feature of the MCU to detect if the primary clock (OSCCLK) is missing when compared to INTOSC1. So when MCD is detected that means your primary clock is missing, if you are using XTAL (external oscillator) then make sure there is no defect in that circuit connection for the boards you are taking about.

I don't think MCD in MCU can be damaged just like that. There is no weakness identified for MCD for any of our MCU's.

Thanks.

hi

Based on the above analysis, it is a problem with the internal missing clock detection circuit of the MCU.

Please help analyzed the cause of the damage.

Hi,

Can you help understand what tests were conducted on the chips that give MCD clockfail signal assertion ?

Are these seen right after production ?

Are you using the XCLKOUT feature to route the XTAL to GPIO for monitoring ? If not could you enable XCLKOUT of XTAL

If the scope shots look normal without any sudden glitches in time that could tell if MCD is false triggering or XTAL has an issue.

If we narrow down to MCU defect then we would need to send the chip for failure analysis, please check with your TI field representative engineer

Thanks

Hi

Can you help understand what tests were conducted on the chips that give MCD clockfail signal assertion ?

Aswer:

HI

Are you using the XCLKOUT feature to route the XTAL to GPIO for monitoring ? If not could you enable XCLKOUT of XTAL

Answer:

the GPIO is used for other function.

hi

TMS320F280025: PLL Reference Clock Lost Detection triggered, Missing-Clock-Detect not - C2000 microcontrollers forum - C2000︎ microcontrollers - TI E2E support forums

This topic feels quite similar to our problem, and ultimately couldn't find the reason.

we don't used DCC.

Hi,

This thread is about a different feature called PLL Reference lost not MCD.

There is a corresponding errata to it as well. Make sure you are not using PLL reference lost detection feature and only using MCD or DCC.

Thanks

That's the problem with us (PLL Reference lost)

There is another question, if the problem did not occur at the time of leaving the factory, will it still occur in the future？This product is already running in the market，not easy to update the hex file.

Youjun,

As errata mentions the feature - PLL Reference Lost should not be used it can trigger spuriously. I would advise to disable feature -PLL Reference lost and use DCC or just MCD.

Using MCD or DCC is sufficient to cover clock failure in runtime. Please look to see if the feature can be disabled

Thanks

Hi

What I mean is that the function (PLL Reference Lost)has already been used and there are currently no problem with the product. Will the problem suddenly occur(it can trigger spuriously) after running for six months or more？

youjun zhang said:

ill the problem suddenly occur(it can trigger spuriously) after running for six months or more？

Yes, since it is random it can trigger spuriously

Thanks