False Tamper detection occasionally

[sanjaykumarsinghbel]

We have used IC : PCA2129T in one of our custom board design.

The schematic of the same is enclosed here, for reference.

Battery used is CR2032 Panasonic, 3.0V. We have used the IC : PCA2129T for RTC time reading and Tamper detection. Battery voltage measured in problematic sets is more than 2.8 V.

PCA2129T is being used in standard mode (as default).

However, Tamper detection is not working reliably. Occasionally false Tamer detection is happening. Note: TSF1 and TSF2 bit  is being read for Tamper detection in our design. (Interrupt line is not being used due to Hardware constraint.)

Also, Sometimes RTC time reading displays incorrect value in Seconds field, (Ex: sometime second field displays value upto 139 Sec !).

Kindly suggest what could be the issue. Kindly do the needful on priority.

Regards,  Sanjay Kumar Singh,

                  sanjaykumarsingh@bel.co.in

[sanjaykumarsinghbel]

Dear G.W.

waiting for your response...

[sanjaykumarsinghbel]

Dear G.W.

Additional query:

If the TS pin is driven to Ground for 6 us(micro second) time, then what will be the impact on PCA2129T w.r.t. Tamper event ?

Kindly suggest.

waiting for your response.

Kindly keep this case active. since few more doubts need to be clarified subsequently.

[sanjaykumarsinghbel]

Additional query:

If the TS pin is driven to Ground for 6 us(micro second) time, then what will be the impact on PCA2129T w.r.t. Tamper event ?

Kindly suggest.

[sanjaykumarsinghbel]

Dear G.W,

Updated schematic is already available as part of this case thread. However please find again (enclosed again).

Please consider R160 as 0 ohm, (since all our PCBs are assembled with R160 as 0 ohm).

waiting for your response.

[sanjaykumarsinghbel]

Dear G.W.

The PCA2129T being used on our equipments are having following  marking on the chip.

PCA2129T/Q

ACY574.

1       CS

knD18422

Kindly let us know if any issue is there with this Batch of the IC.

Also, Kindly let us know if any false tamper detection issue is there with this Batch of the IC.