ESP8266EX SCH design covers the following five parts:
• Power supply;
• Power on sequence and reset;
• Flash;
• Crystal oscillator;
• RF.
2.2.1. Power-supply Pins
Digital Power-supply Pins
ESP8266EX has only two digital power-supply pins (abbreviated as VDDPST in the circuit diagram),
Pin11 and Pin17. In digital power supply, there is no need to add additional filter capacitors. The
operating voltage range of digital power-supply pins is between 1.8V and 3.3V.
Figure 4 ESP8266EX Digital Power-supply Pins
Analog Power-supply Pins
ESP8266EX has 5 analog power-supply pins (abbreviated as VDD33 in the circuit diagram), including
Pin 1, Pin 3, Pin 4, which provides internal power supply for internal PA and LNA respectively, and Pin
28, Pin 29, which supplies power for internal PLL. The operating voltage range of the analog power-
supply pins is between 1.8V and 3.3V.
It should be noted that the power supply channel might be damaged due to the sudden increase of
current when ESP8266EX is transmitting analog signals. Therefore, an additional 0.1uF capacitor with
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