ESP32 Forum

Hi,

Since flash chips used in WROOM-32E modules have minimum supply voltage of 2.7V, thus limiting otherwise more flexible ESP32-D0WD-V3 (its minimum supply is 2.3V), I was thinking of using the ESP32 + external flash (+ XTAL + antenna) instead of the module.

I found couple of PNs that look compatible in every way but I'd like to double check:

1.65V - 3.6V:
PUYA P25Q32U
GigaDevice GD25WQ32EEIGR
Macronix MX25R3235FM2IH0

2.3V - 3.6V:
PUYA P25Q32H
ISSI IS25LP040E

Has anyone had any experience with these? I'm particularly interested in PUYA's chips since they are the cheapest and highly available.

PS. Any idea why Espressif says WROOM modules work from 3.0V and not 2.7? They already said flash is the limiting factor so I'm curious why not going with what the flash chip manufacturer specifies.

Cheers!

esp_zag0 wrote: PS. Any idea why Espressif says WROOM modules work from 3.0V and not 2.7? They already said flash is the limiting factor so I'm curious why not going with what the flash chip manufacturer specifies.

Hi esp_zag0,

Flash in that module is powered from ESP32's VDD_SDIO pin. The voltage on that pin is lower than VDD due to drop on internal 6 Ω resistor (the flash is drawing some current), see notes in section "Recommended Operating Conditions" of ESP32 datasheet

ESP_krzychb wrote: Hi esp_zag0,

Flash in that module is powered from ESP32's VDD_SDIO pin. The voltage on that pin is lower than VDD due to drop on internal 6 Ω resistor (the flash is drawing some current), see notes in section "Recommended Operating Conditions" of ESP32 datasheet

Thanks ESP_krzychb.

If I go with 1.65 - 3.6V external flash, do you recommend powering it from a VDD_SDIO at 3.3V or adding a pullup to GPIO12 to switch VDD_SDIO to 1.8V? Both should work fine I guess?

If going with 1.8V, should I use BOOTLOADER_VDDSDIO_BOOST_1_9V?