ESP32 Forum

Posted: **Thu Feb 19, 2026 9:31 pm**

So the default output voltage of VDDO_FLASH is 3.3V and it can be set to 1.8V by burning fuse EFUSE_0PXA_TIEH_SEL_0

At the same time the technical manual states:

Some PSRAM chips are 1.8 V devices and some are 3.3 V. The working voltage of the PSRAM chip must match the working voltage of the flash component. Consult the datasheet for your PSRAM chip and ESP32-P4 device to find out the working voltages. For a 1.8 V PSRAM chip, make sure to either set the MTDI pin to a high signal level on bootup, or program ESP32-P4 eFuses to always use the VDD_SIO level of 1.8 V. Not doing this can damage the PSRAM and/or flash chip.

And the only two P4 SOCs available come with 1.8V integrated PSRAM. So 3.3V Flash doesn't even seem to be usable with these P4 chips without destroying the PSRAM, and it makes even less sense to have 3.3V be the default instead of 1.8V.

What am I missing?

Posted: **Sat Feb 21, 2026 1:23 am**

the only two P4 SOCs available come with 1.8V integrated PSRAM

I believe that is referring to connected an external one.

Posted: **Wed Feb 25, 2026 1:25 pm**

the only two P4 SOCs available come with 1.8V integrated PSRAM
I believe that is referring to connected an external one.

but the power for the in package PSRAM needs to be provided from the outside through VDD_PSRAM_1 and VDD_PSRAM_2 pins and I assume that needs to be 1.8V if the in-package PSRAM is listed as 1.8V in the datasheet?

ESP32 Forum

Why is the P4's Flash LDO 3.3V by default?

Why is the P4's Flash LDO 3.3V by default?

Re: Why is the P4's Flash LDO 3.3V by default?

Re: Why is the P4's Flash LDO 3.3V by default?