AM437x simplified power sequencing and RTC

hi,
I have already read those two documents,
Our idea is to use the TPS65218 and apply the datasheet "7.3.1.12.2 Applications Without Battery Backup Supplies"
And still be able to chose between the two options in the last table of:
"processors.wiki.ti.com/.../AM437x_Schematic_Checklist"
in the RTC chapter
Option 1:
RTC timer functionality
but no RTC-only mode
Option 2:
RTC feature disabled
Description of the function's utility:
1)RTC timer functionality but no RTC-only mode:
If you will be using the RTC feature but do not need RTC-only mode. This use case allows you to use the Real Time clocking features (eg, keeping time), but you do not need to support the low power RTC-only mode.
2)RTC feature disabled:
If you will never use the RTC features. In this use case, the RTC functions are fully disabled.

The 32k crystal is not installed as if I understand correctly the AM437x datasheet "5.13.2.2 Input Clock Specifications"
"OSC1 is disabled by default after
power is applied. This clock input is optional and may not be required if the RTC is configured to receive a
clock from the internal 32k RC oscillator (CLK_RC32K) or peripheral PLL (CLK_32KHZ) which receives a
reference clock from the OSC0 input."
Regards,
Laurent

Please note that the 32k RC oscillator (CLK_RC32K) is inaccurate and there may be large frequency deviations. If you do not want to use an external crystal the better option is to use the peripheral PLL (CLK_32KHZ) clock source.

As for connections, please post the relevant schematics.

Ok duly noted

We will use the peripheral PLL (CLK_32KHZ) clock source.

Regards

Hello Biser,

Here are the our design.

8510CPU_xxxx_SCH_(STD).pdf

Regards,

Hello Biser,

Thank you for your feedback.

Here are the modifications as I understand them.

Since PWRONRST is pulled up to 3v3 by 10k in the Power schematic sheet I will use a 100k/100k divider.

the high level will be:

200/210*3.3=3.14 for PWRONRST (min expected 0.65*3.3=2.15)

and

100/210*3.3=1.57 for RTC_PWRONRST (min expected 0.65*1.8=1.17)

So everything should work as expected.

Regards,

Laurent

 

Seems OK to me.