Concerns about HDQFP100 pin failure in S32K312

[hirokado]

Hello Support team,

I have a question about S32K312 of HDQFP100 from the viewpoint of functional safety.

[Questions]
1.
VSS/V25/V11/VDD_HV_A has multiple pins, but are they connected internally?

2.
If the VSS/V25/V11/VDD_HV_A pin fails with pin open, what are the concerns?

3.
What are the concerns if the V25/V11 pin is shorted to VSS and fails?

4.
If the VREFL/VREFH pin fails with pin open, what are the concerns?

Best regards,
Hiroyuki Kadowaki

[hirokado]

Dear Support team,

How about this?
My customer contacted me and wanted a quick answer.

=========================================
[Questions]
What concerns do you have in each of the following cases?
- V25 (11pin) was shorted to 10pin (VDD_HV_A)
- VDD_HV_A and VSS are shorted
- VREFH shorted to VREFL
- V11(60pin) was shorted to 59pin(PTE7) which outputs low
=========================================

Best regards,
Hiroyuki Kadowaki

[Yashwant_Singh]

Hello,

Please find some answers below:

• V25 (11pin) was shorted to 10pin (VDD_HV_A): If V25 pins are shorted to VDD_HV_A then this condition should be detected by the HVDs on V25.
• VDD_HV_A and VSS are shorted: If VDD_HV_A gets shorted to ground, then it would cause a under-voltage event which would be detected by on-chip low voltage detector (LVD) and off-chip watchdog monitors (VDD_HV_A being the source of V11 which is the core supply. 
• VREFH shorted to VREFL: This should be covered via SM1.ADC_SELFTEST.
• V11(60pin) was shorted to 59pin(PTE7) which outputs low.: If V11 gets shorted to low voltage, then it would cause a under-voltage event which would be detected by on-chip low voltage detector (LVD) and off-chip watchdog monitors (V11 which is the core supply)

Thanks!

-Yashwant

[hirokado]

@Yashwant_Singh 

Dear Yashwant,

Thank you for your reply.
It's very helpful for me.

I have some additional questions.

[Question]
1.
Is it possible to detect LVD/HVD of V11/V25?
It seems that HVD11/HVD25 can be detected by the following two registers, but it cannot be detected by LPM.
Also, I can't find the LVD for V11/V25.
=====================================
S32K3xx Reference Manual, Rev. 8
43.7.2 Low Voltage Status And Control (LVSC)
11:HVD11S
10:HVD25S
=====================================

2.
>- V25 (11pin) was shorted to 10pin (VDD_HV_A): If V25 pins are shorted to VDD_HV_A then this condition should be detected by the HVDs on V25.
What will happen if I leave it alone after being detected by V25's HVD?
Does S32K3 have HVR?
There was an LVR in the document below, but there was no HVR.
=====================================
S32K3xx Reference Manual, Rev. 8
43.7.2 Low Voltage Status And Control (LVSC)
23:LVR11LPF
21:LVR25LPF
=====================================

3.
>- VREFH shorted to VREFL: This should be covered via SM1.ADC_SELFTEST.
I understand that it can be detected using SM1.ADC_SELFTEST.
But I can't find SM1.ADC_SELFTEST.
The S32K3 self-test states that there are the following algorithms and steps, but there is no description of SM1.
=====================================
S32K3xx Reference Manual, Rev. 8
60.3.17.2 Self-test
Table 335. Self-test steps
=====================================
SM1.ADC_SELFTESTについて、ドキュメントのどこに記載があるか教えてほしい

I would like to know where SM1.ADC_SELFTEST is described in the document.

Also, what happens if "VREFH shorted to VREFL" is left as is?
I think this is due to a decrease in ADC performance, is that correct?

4.
>V11(60pin) was shorted to 59pin(PTE7) which outputs low.:
>If V11 gets shorted to low voltage, then it would cause a under-voltage event which would be detected by on-chip low voltage detector (LVD) and off-chip watchdog monitors (V11 which is the core supply)
What will happen if I leave it as it is detected?

Best regards,
Hiroyuki Kadowaki

[hirokado]

@Yashwant_Singh 

Dear Yashwant and Support team,

How about this?
I added one to the question on April 2, 2024.

=========================================
[Questions]
What concerns do you have in each of the following cases?
- V25 (11pin) was shorted to 10pin (VDD_HV_A)
- VDD_HV_A and VSS are shorted
- VREFH shorted to VREFL
- V11(60pin) was shorted to 59pin(PTE7) which outputs low
=========================================

Best regards,
Hiroyuki Kadowaki

[hirokado]

@Yashwant_Singh 

Dear Yashwant,

I apologize for asking so many questions.
I have some additional questions.

[Questions]
What concerns do you have in each of the following cases?
- V25 (11pin) was shorted to 10pin (VDD_HV_A)
- VDD_HV_A and VSS are shorted
- VREFH shorted to VREFL

Best regards,
Hiroyuki Kadowaki

[hirokado]

Dear Yashwant,

All the best wishes in 2024.

How about the following question ?
Is my understanding correct ?

>>2.
>>If the VSS/V25/V11/VDD_HV_A pin fails with pin open, what are the concerns?
>I think there is no problem functionally.
>However, related to your answer below, I think there are concerns about performance impact.
>>The multiple supply pins for a single supply are connected inside however we have not analyzed the behavior of the device when one supply pin fails - the device may or may not become reliable. In either case we expect the internal voltage monitoring or the external watchdog to detect a fault and indicate safe state to the external system.

Best regards,
Hiroyuki Kadowaki

[Yashwant_Singh]

Hello Hiroyuki,

Wishing you a happy new year as well !!

We have confirmed from the design teams that the appropriate IR drops (due to pin failures or otherwise) for the supplies are already accounted for in the LVD/HVD thresholds and so if the supplies fail then the LVDs/HVDs would trigger before the chip performance is impacted.

Thanks!

-Yashwant

[hirokado]

Dear Yashwant,

Thank you for your answer and confirmation.

I understood from your answer below.
I'll respond to customers.
- If a power supply fails, the LVD/HVD can detect it before chip performance degrades.

Best regards,
Hiroyuki Kadowaki

[hirokado]

Dear Yashwant,

Thank you for your reply.
I almost understand.

But, how about the following question?
>2.
>If the VSS/V25/V11/VDD_HV_A pin fails with pin open, what are the concerns?
I think there is no problem functionally.
However, related to your answer below, I think there are concerns about performance impact.
>The multiple supply pins for a single supply are connected inside however we have not analyzed the behavior of the device when one supply pin fails - the device may or may not become reliable. In either case we expect the internal voltage monitoring or the external watchdog to detect a fault and indicate safe state to the external system.

Best regards,
Hiroyuki Kadowaki

[Yashwant_Singh]

Hello Hiroyuki,

The multiple supply pins for a single supply are connected inside however we have not analyzed the behavior of the device when one supply pin fails - the device may or may not become reliable. In either case we expect the internal voltage monitoring or the external watchdog to detect a fault and indicate safe state to the external system.

In case shorting of V25/V11 with VSS, the logic would stay in reset. In case V11 goes very low then external watchdog might also kick in as stated earlier.

Regarding VREFH and VREFL which serve as the reference voltage for the ADCs, running the ADC self test periodically should provide sufficient coverage for the failure of these supplies.

Thanks!

-Yashwant

[hirokado]

Dear Support team,

How about this?
If you have an answer to some of the questions, please respond.

Best regards,
Hiroyuki Kadowaki