can modify buck3 output from 3.3 to 1.8?

[rishi@smufsbio.com]

Hi there,
I am trying to make battery based design, just wondering modifying VINOK_Rise from 3.5 to 3.3V is enough. Or i should also switch Buck3 output from 3.3 to 1.8 as well.
I am confused as in the osd datasheet seems like you discourage to modify any outputs of pmic regulators.
[Section 7.6]
“.. While some of the output voltages of the regulators can be adjusted, they
should not be adjusted….”.
The regulators which i should not modify includes buck3?

Thanks, Rishi

[rishi@smufsbio.com]

Hi All,
I am sorry probably i posted my question as soon as it came to my mind….
Reading further clarified i think 7.6.11 table clearly shows what should NOT be modified.

Thanks, Rishi

[Neeraj Dantu]

Rishi,

Based on the battery output voltage, you might have to configure VDD to be 1.8V instead of 3.3V. This is recommended if you are using a battery according to the PMIC datasheet. Please take a look at the Power System Overview for OSD32MP1: https://octavosystems.com/app_notes/osd32mp1-power-system-overview/.

Best,

Neeraj

[rishi@smufsbio.com]

Hi Neeraj,
Thanks, After some load testing we decided to use our external power supply in our initial prototype.
Yes you are right we will use VDD 1.8 but we still need 5 and 3.3 lines.

As our 5V load is around 400mA and our 3.3 load is USB hub and emmc chips which is around 250mA.

So after testing for like 20-30 minutes voltage was dropping a lot, 5.2 V was going down to 4.8~4.9V from BST_OUT and 3.3V was going down to 2.7~2.8V from LDO2.

So to be on safer side we decided to have our own external supply.

Thanks, Rishi

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