Unable to power off i.MX6UL

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Unable to power off i.MX6UL

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sguy
Contributor III

Hi all,

On a board with a i.MX6UL chip, I have troubles when trying to power off the device.
Any time I power off the device, either by a software power off or by long assertion of the onoff pin, the system boots up again immediately.
I made sure that the onoff pin remains high after the power off, and that the VDD_SNVS_IN stays stable.
Do you know what else might cause such behavior?
Thanks.

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Guy

one can check pmic_on_req signal as it controls pmic (with pwron signal) or board

power circuitry, example can be found on

Q&A: How is mx6 PMIC_ON_REQ under SW control? 

Best regards
igor
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sguy
Contributor III

On power down, the pmic_on_req stays low around 2.2ms and then goes up again.
I expect it to stay low until pressing the ONOFF. Is this correct?

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igorpadykov
NXP TechSupport
NXP TechSupport

one can check sect.10.4.1.4.3.3 SoC  i.MX6UL RM :
Since SNVS_LP is powered through an "always on" supply,
configuring the SNVS_LP DP_EN to "1" allows changing the PMIC_ON_REQ pad
(SoC on/off supply indication to the PMIC) through the ONOFF pad.

Best regards
igor

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sguy
Contributor III

The SNVS_LP DP_EN is set to "1" on my systems.


According to figure 49-3 (section 49.4.1 of imx6ulrm), after long assertion of onoff, the system should stay in the SRTC state.

On my system, the SNVS supply is not removed, the ONOFF button isn't asserted, and I didn't enabled any tamper or timer wake up. However, the chip does move to the ON state for some reason.


Is there any other scenario that might cause the system to restart?

Thanks,
Guy,

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igorpadykov
NXP TechSupport
NXP TechSupport

one can check this on i.MX6UL EVK board, use linux powerof command

then pressing ONOFF will wake system.

Best regards
igor

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sguy
Contributor III

Yes. That’s how it should work. However, on my custom board it doesn't work like that and I'm trying to debug that.

Is there any signal, beside those I mentioned, that might power up the system?

Thanks,
Guy,

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