RT1064 | problem with shutdown

[shai_b]

Hello team,

My customer has an issue when he tries to use the "power_mode_switch_rtos"  to shutdown the MCU and the system get stuck on:

When he tried the low-power mode example code and enter LPM_EnterSNVS (shutdown mode) on his PCB. it looks like there is a problem since the power consumption stays the same (all other modes in this demo are working perfectly).

Could you please advise what is wrong?

Thanks in advance

Kind regards,

Shai

iMXRT1064 

[behnam1367]

Hello everyone, @Omar_Anguiano 

I am facing an issue with the SNVS (Secure Non-Volatile Storage) backup domain current on an i.MX RT1064 (MIMXRT1064CVJ5B) microcontroller and would appreciate your help.

The Core Problem:
The backup battery for the SNVS domain is discharging too quickly. The battery is a CR1220 with a 35mAh capacity.

Measurements & Discrepancy:

The microcontroller is running at 532 MHz.

According to application note AN12245, the expected input current for the SNVS domain should be around 25.7 µA.

However, my measurements show a constant current draw of 38 µA (Note: 38 µA is more than 25.7 µA, indicates something is not configured correctly and the MCU might not be in the expected low-power state).

This 38 µA current remains constant even when the main power supply (VDD_HIGH_IN) is removed.

Crucially, the current remains at 38 µA even when I intentionally place the chip into its SNVS low-power mode. It does not drop to the expected 10µA range.

What I've Already Tried:
I have already disabled the internal switch between VDD_HIGH_IN and SNVS_VDD by setting bit 12 (DISCON_HIGH_SNVS) in the XTALOSC24M_MISC0 register. Despite this, the current draw remains unchanged.

The key questions are:

Why is the SNVS current a constant 38 µA instead of the expected ~25.7 µA in active mode?

Why does this current not decrease when entering SNVS mode, and why is it not in the 10-12 microamp range as expected for a proper backup state?

What could be preventing the chip from entering a true low-power SNVS state?

I am attaching the relevant schematic portion for the power and SNVS section below. Any insight into what I might be missing would be greatly appreciated.

[Sreeja]

Hello @behnam1367

Could you please share how you resolved excessive battery drain issue?

[MNM]

I’m experiencing the same SNVS backup current issue on the i.MX RT1064 with a BR2330 coin cell battery. Could you please share how you resolved the excessive battery drain issue?

[lucas_cao]

I supposed it caused by schematic design.

[Omar_Anguiano]

Hello
I hope you are well.

This may be caused by a hardware issue on the PCB however first let me suggest some testing to discard some other causes.
Which SDK version are you using? Are you able to enter that power mode by long pressing the ON/OFF button? Please make sure that the wakeup source is enabled:

GPIO_ClearPinsInterruptFlags(APP_WAKEUP_BUTTON_GPIO, 1U << 
                             APP_WAKEUP_BUTTON_GPIO_PIN);
/* Enable GPIO pin interrupt */
GPIO_EnableInterrupts(APP_WAKEUP_BUTTON_GPIO, 1U << 
                      APP_WAKEUP_BUTTON_GPIO_PIN);
NVIC_ClearPendingIRQ(APP_WAKEUP_BUTTON_IRQ);
NVIC_EnableIRQ(APP_WAKEUP_BUTTON_IRQ);
/* Enable the Interrupt */
EnableIRQ(APP_WAKEUP_BUTTON_IRQ);
/* Enable GPC interrupt */
LPM_EnableWakeupSource(APP_WAKEUP_BUTTON_IRQ);

Best regards,
Omar

[shai_b]

Hi @Omar_Anguiano ,

Thanks for your inputs, I need to double-check their SDK version, but I wanted to note that they use an external DC/DC to power the MCU Core, so I assume this could be why the MCU does not get into shutdown mode.

Also, the ON/OFF button does not work.

What is your feedback about the above, Thanks in advance

KR,

Shai

[Omar_Anguiano]

How is the PMIC_ON_REQ connected to the DCDC? It will be helpful to check the power rails to check their compliance with the Hardware Development Guide.
I don't know if you are able to share the schematic through this media but it will be helpful to check it.

Best regards,
Omar