Imx6Q with MMPF0100,how to store data safely when power down occurs?

[JunqiYu]

Thanks a lot.

Sorry,I close the pre problem accidentally.So I revise it and post it again.

I have one imx6q sabre sd board,with  ref design files iMX6Q-SABRE-SDB-DESIGNFILES.zip.

Now I have some questions need your help.

q1.When system power off, what's the best design for imx6 to store data safely with MMPF0100 before shutdown?Are there a ref realization for imx6q to solve the power off problem?

q2.When board power down occurs without coin battery,Vin begins to fall,how long will MMPF0100 take from detected power down(triggering the SDWNB or LOWNIVI) to entering the coin cell mode or fails to work due to the lack of power?Is the time long enough for i.MX6Q to store several bytes data and disable its SNVS power?

q3.When imx6q  interrupt irq 36(pmic power off interrupt request) will be asserted?How it is actived?Trigger by what signal? 

q4.Which ocurs first in MMPF0100，SDWNB or LOWNIVI？

q5.If MMPF0100 pin LiCELL connects a cell battery,can it supports i.Mx6Q to save some data then shutdown itself gracefully when board power off?

Best regards

junqiyu

[weidong_sun]

@JunqiYu,
对于MMPF0100，它的输入VIN最小也要3.3V，才能让CPU处于一个正常工作状态。如果仅仅依靠PMIC掉电时间，恐怕很难保证CPU是否来得及保存数据，基本没希望,因为PMIC内部就是DCDC和LDO的组合，没有特殊机制。但是，数据非常小的话，您可以尝试使用给超过13000uF以上的电容试试，这个电容值我曾经在车载设备上电瓶和发动机之间切换电源用的，只是给你参考一下，意思是这个电容可能需要很大。

Have a nice day!
weidong

[weidong_sun]

Hi,

There is only one core issue of the several issues you are concerned about: how to give your board enough time to save the unsaved data when the power is off.
However, the few issues that you care about, no matter how you work, will not achieve your goals. The following suggestions are for your reference:
1. The board supports battery backup
According to the amount of data you want to save, evaluate how long the CPU needs to continue to run after power off, and then select the 3.6V~4.2V battery capacity.
2. Your design needs a circuit to detect the adapter input. Then you will know whether the power has been cut off and decide whether to start data saving.

【Note】
If you don't want to use the above method, you can also consider the mechanism of saving data regularly in the software. The interval can be made very small, but there will always be a little bit of data too late to save.

----Chinese-----

您所关心的几个问题，核心问题只有一个：如何在断电的时候，让你的板子有足够的时间保存那些未保存的数据。
但是，您关心的几个问题，无论如何工作，都无法实现您的目标。下面的建议给您参考：
1. 板子支持备用电池
根据您要保存的数据量的大小，评估CPU需要在断电后继续运行多长时间，然后选择3.6V~4.2V电池容量。
2. 您的设计中需要有检测适配器输入的电路。这样您才会知道是否已经断电，并决定是否启动数据保存。

【注】
如果你不想采用上面的方法，你也可以考虑软件中采用定时保存数据的机制，间隔可以做得很小，但总是会有一点点数据来不及保存。

Have a nice day!

B.R,

weidong

[JunqiYu]

Thanks  a lot.

I'm sure your solution will solve the problem. The amount of data I need to save is not large. Maybe I just need to record the outage log,just several bytes.

Because I used imx6q and mmpf0100 for the first time, I hope to know the performance of NXP chip in this aspect. So I still hope to got answers of those questions.

Mmpf0100, as a power management chip, considers undervoltage detection and power failure detection, and can interact with imx6q. I want to know what i.mx6q can do before it completely fails to work based on these functions? For example, how many bytes of data can be stored?

[JunqiYu]

@weidong_sun 谢谢您的回答，元宵节快乐。

我的目标的确是解决断电数据及运行环境保护问题，您说的方案可行。

因为第一次用Imx6Q和MMPF0100芯片，前面提出的问题想更深入地了解芯片在这方面的性能和机制；另一方面，我们的板卡尺寸有限，如果能够在已有电路的支持下实现目标从空间和成本上更好，我们需要保存的数据很少，可能只是记录断电日志。

MMPF0100作为NXP PMIC芯片，其已经考虑了欠压检测和掉电检测，并与Imx6 CPU之间有交互通道。我希望了解其具体的性能，特别是时间上的性能，例如从系统断电到给出欠压信号、给出PMIC即将停止给CPU供电信号之间需要多长时间？这个时间是否足够IMX6Q记录下断电事件？