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K21 - DryIce data loss, high VBAT current

Question asked by Michael Haben on Apr 13, 2018
Latest reply on Apr 27, 2018 by Michael Haben

We're using the DryIce tamper module in a K21, and seeing unexplained loss of stored data even with all tamper-sources disabled.

Our suspicion was that the VBAT line was somehow glitching below the DryIce minimum limit of 1.71V, despite having a 1kohm/1uF RC filter on it - in the course of investigation, we've seen up to 28uA being drawn by the K21 VBAT line (28mV across the 1k resistor) when the main power-supply is switched off, way above any figure given in the datasheet!  So please can anyone tell me...

 

1.  Does VBAT supply any K21 modules other than DryIce and the RTC?

 

2.  What could be causing such a high current to be drawn?

 

3.  Is anyone using the K21 DryIce tamper module successfully and reliably?  Any tips to share?

 

thanks,  Mike

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