Power Supply; Digital Power Supply; Analog Power Supply - Espressif Systems ESP32 Series Manual

3.1 Schematics 3 SCHEMATICS AND PCB LAYOUT DESIGN
A detailed description of these aspects follows.

3.1.1 Power Supply

3.1.1.1 Digital Power Supply

Pin19 and Pin37 are the power supply pins for RTC and CPU, respectively. The digital power supply operates
in a voltage range of 1.8V ~ 3.3V. We recommend adding extra filter capacitors close to the digital power supply
pins.
The internal LDO of VDD_SDIO can be the 1.8V or 3.3V power supply for the external circuit, with a maximum
current of about 40 mA. The user can add a 1µF filter capacitor close to VDD_SDIO. When VDD_SDIO connects
to VDD3P3_RTC, the LDO will be disabled.
Figure 4: ESP32 Digital Power Supply Pins

3.1.1.2 Analog Power Supply

Pin1, Pin43 and Pin46 are the analog power supply pins. Pin3 and Pin4 are the power supply pins for the power
amplifiers. It should be noted that the sudden increase of current, when ESP32 is in transmitting mode, may cause
Espressif Systems 14 ESP32 Hardware Design Guideline V1.0