STM32H7S78-DK: How to determine VOS0, VOS1, VOS2 and VCore for estimating lifetime

[rk_iot]

Hello,

according to this document 

https://www.st.com/resource/en/application_note/an5337-guidelines-for-estimating-stm32h7-mcus-lifetime-stmicroelectronics.pdf

the expected lifetime of a STM32H7 mcu depends on the parameters Tj (junction temperature), VOS0, VOS1, VOS2, VCore and operation ratio.

How can we determine VOS0, VOS1, VOS2 and VCore for the STM32H7S78-DK board?

Thanks in advance,

rk_iot

[AScha.3]

> How can we determine

Just your decision, you select the vosx you want.

And so you also fix the frequency the CPU is working on and this way also the current consumption and the lifetime.

Depends on expected max ambient temperature...and your decisions.

[rk_iot]

Thank you @AScha.3 !

So when running the CPU with 600 MHz, what will be the values for VOS0, VOS1, VOS2 and VCore?

We could not find these values in the reference manual:

https://www.st.com/resource/en/reference_manual/rm0477-stm32h7rx7sx-armbased-32bit-mcus-stmicroelectronics.pdf

Thank you and best regards,

rk_iot

[mƎALLEm]

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@rk_iot wrote:

Thank you @AScha.3 !

So when running the CPU with 600 MHz, what will be the values for VOS0, VOS1, VOS2 and VCore?

We could not find these values in the reference manual:

https://www.st.com/resource/en/reference_manual/rm0477-stm32h7rx7sx-armbased-32bit-mcus-stmicroelectronics.pdf

Thank you and best regards,

rk_iot

---

This kind of information can be found in the datasheet but seems only two voltage levels are available (low and high)

[AScha.3]

Read it in DS, i am sitting in a train now.

In DS you see also the values of average power consumption, the current, at some different ambient temperatures and so you get some feeling, what and why high temperature reduces life time of these high speed design chips.

At higher temp the CPU current increase nonlinear and so the lifetime suffers.

So try to keep it as cool as possible and it will work long time.

Afair it's vos0, the highest voltage, because close to max clock.

[rk_iot]

Thank you @mƎALLEm and @AScha.3 

our confusion probably stems from the fact that AN5337 is not intended for STM32H7R7/7S7.

It says it is only applicable for:

STM32H742, STM32H743/753, STM32H745/755, STM32H747/757, STM32H750 Value line
STM32H723/733, STM32H725/735, STM32H730 Value line

Is there a corresponding document for STM32H7R7/7S7?

We would need a way to reliably determine the life time expectancy for our application. Maybe it is enough to measure the temperature on the chip surface and know the core voltage and core frequency to get an good estimation?

Thank you and best regards,

rk_iot

[mƎALLEm]

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@rk_iot wrote:

Is there a corresponding document for STM32H7R7/7S7?

---

There is no document for STM32H7R7/7S7 devices but the plan is to update the AN5337. I don't know when it will be updated.

But according to what I found internally as information:
The estimation of the current profile is given in the Table below. 

The target for the industrial mission profile is given below also.
Estimated lifetime @ Operating ratio 100%

Hope that helps.

[rk_iot]

Hello @mƎALLEm ,

thank you for that helpful information!

What exactly is the difference between the first and the second table? What does "industrial mission profile" mean?

Our guess is that the first table is for STM32H7S7L8H6 and the second "industrial mission profile" table is for STM32H7S7L8H6H?

But we could not find that information on the product page or datasheet. Can you tell us where to find the differences between STM32H7S7L8H6  and STM32H7S7L8H6H?

Thank you and best regards

rk_iot

[mƎALLEm]

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@rk_iot wrote:

Hello @mƎALLEm ,

Our guess is that the first table is for STM32H7S7L8H6 and the second "industrial mission profile" table is for STM32H7S7L8H6H?

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No the H prefix in that situation means the availability of the HexaSPI interface: H6H: HexaSPI is available / H6: HexaSPI is not available.

I'm not expert of lifetime/profile subject but it's up to you to define which profile you decide to use based on your application, its usage and its environment.

For example, if your product in a harsh environment in which TJ should reach 130°c , you should use VOS low/400MHz and the lifetime will be 10 years.

[rk_iot]

@mƎALLEm but the first table says 

10 years with VOS high and Tj=55°C

and the second table

10 years with VOS high and Tj=74.3°C

what is the difference between the two tables if it is not the grade of the chip? How is "industrial mission profile" defined in that context?