K21 secure storage

[PHXFAE]

I have a customer who is using the K21 with the tamper protection.

They are at the point of wanting to use the K21 32 bytes of secure storage.

The data sheet says the minimum Vbat is 1.71V.  Is this the minimum to preserve the data in the 32 bytes?

What is the Vbat voltage to guarantee the 32 bytes of secure storage is cleared?

With the K21 unpowered except Vbat can a tamper event clear the 32 bytes?

Is the only way to clear the 32 bytes of secure storage to lower Vbat?

Thx for the help.

[PHXFAE]

I am logged in and there is no button like you show anywhere on the page.

[PHXFAE]

Where is the correct answer button.  I don't see it.

[PatriciaTeran]

You have to Log in, in order to see it. It should be right below the post with the answer, like this 

  

[PatriciaTeran · Accepted solution]

Hi, Alex

The VBAT min that you are refering to is the MIN for the RTC battery supply voltage (1.71V), if you go to section 2.2.1 of the datasheet, you will see the MIN voltage to retain the VBAT register file is between 0.8V - 1.5V, any less will be considered as a VBAT power-on reset  and it will erase the 32 byte VBAT register file.

The only way to clear the 32 bytes is during VBAT power-on reset, this module is not affected by the other reset types.

Hope it helps,
Regards!

Patricia Teran

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