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i.MX6UL rev 1.0 - VDD_SNVS_IN 400µA in Power-Off Mode

Question asked by Dirk Lohse on Mar 29, 2016
Latest reply on Apr 11, 2016 by jamesbone

We measured the current drawn from VDD_SNVS_IN (3.0V coin cell CR2032) and got the following measurements:

 

Multimeter: Fluke 8846A:

Supply (3.3V) Off, RTC in Reset (not adjusted):     +209uA

Supply (3.3V) On, RTC adjusted, CPU running:      +11uA (because coin cell voltage is about 3.2V and LDORTC is 3.0V)

Supply (3.3V) On, Sleep Mode (suspend to RAM): +16uA

Supply (3.3V) Off, RTC adjusted:                             +439uA (this should be lower than 25uA)

 

In the IMX6ULCEC.pdf Rev. C

Page 32:

 

-> Current consumption 4uA + 1uA + 1.5uA = 6.5uA

 

Why did we get 439uA current drawn from the coin cell in power-off mode? This reduces backup time rapidly to some days/weeks.

The SNVS is clocked from an external 32kHz crystal (not the 40kHz ring oscillator).

We using Linux Kernel 4.3.0, started from u-boot. Could there be an configuration mistake (e.g. tamper detection enabled) or is this an hardware issue? I don't think we need tamper detection, but may be it's activated somewhere.

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