Espressif Systems ESP8684 Series, Hardware Design Manuallines, Page: 2 / 28

Contents
Contents
1 Overview
5
2 Schematic Checklist
6
2.1 Power Supply 7
2.1.1 Digital Power Supply 7
2.1.2 Analog Power Supply 7
2.2 Power-on Sequence and System Reset 8
2.2.1 Power-on Sequence 8
2.2.2 System Reset 8
2.2.3 Power-up and Reset Timing 9
2.3 Flash 9
2.4 Clock Source 9
2.4.1 External Clock Source (compulsory) 9
2.4.2 RTC (optional) 10
2.5 RF 10
2.6 UART 11
2.7 ADC 11
2.8 Strapping Pins 11
2.9 GPIO 12
3 PCB Layout Design
15
3.1 General Principles of PCB Layout 15
3.2 Positioning a Module on a Base Board 15
3.3 Power Supply 17
3.4 Crystal Oscillator 18
3.5 RF 19
3.6 UART 21
3.7 Typical Layout Problems and Solutions 21
3.7.1 Q: The current ripple is not large, but the TX performance of RF is rather poor. 21
3.7.2 Q: The power ripple is small, but RF TX performance is poor. 22
3.7.3 Q: When ESP8684 sends data packages, the power value is much higher or lower than the
target power value, and the EVM is relatively poor. 22
3.7.4 Q: TX performance is not bad, but the RX sensitivity is low. 22
4 Hardware Development
23
4.1 ESP8684 Modules 23
4.2 ESP8684 Development Boards 23
5 Hardware Design Checklist Form
24
6 Related Documentation and Resources
25
Glossary
26
Espressif Systems 2
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ESP8684 Series Hardware Design Guidelines v1.1