Analog Power Supply - Espressif Systems ESP32 Hardware Design Manuallines

Chapter 3. Schematic Checklist
it is recommended that users add a 2 kΩ ground resistor and a 4.7 μF ground capacitor close to VDD_SDIO.
See Figure ESP32 Schematic for 1.8 V VDD_SDIO Power Supply
• When VDD_SDIO operates at 3.3 V, it is driven directly by VDD3P3_RTC through a 6 Ω resistor (internal to
the chip), therefore, there will be some voltage drop from VDD3P3_RTC. When the VDD_SDIO outputs 3.3
V, it is recommended that users add a 1 μF filter capacitor close to VDD_SDIO. See Figure
for 3.3 V VDD_SDIO Power Supply
Attention: When using VDD_SDIO as the power supply pin for in-package or off-package 3.3 V flash/PSRAM,
the supply voltage should be 3.0 V or above, so as to meet the requirements of flash/PSRAM's working voltage.
Fig. 3: ESP32 Schematic for 1.8 V VDD_SDIO Power Supply Pin
Fig. 4: ESP32 Schematic for 3.3 V VDD_SDIO Power Supply Pin
VDD_SDIO can also be driven by an external power supply as shown in Figure
Powered by External Supply.

3.1.2 Analog Power Supply

ESP32's VDDA and VDD3P3 pins are the analog power supply pins, working at 2.3 V ~ 3.6 V.
For VDD3P3, when ESP32 is transmitting signals, there may be a sudden increase in the current draw, causing
power rail collapse. Therefore, it is highly recommended to add a 10 μF capacitor to the power rail, which can work
in conjunction with the 1 μF capacitor(s).
Add a LC circuit on the VDD3P3 power rail to suppress high-frequency harmonics. The inductor's rated current is
preferably 500 mA and above.
Place appropriate decoupling capacitors near the other analog power pins according to Figure
Analog Power Supply Pins.
Espressif Systems
Pin.
9
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ESP32 Schematic for VDD_SDIO Pin
ESP32 Schematic for
ESP32 Schematic
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