Espressif Systems ESP8266EX, Руководство пользователя по оборудованию, Страница: 17 / 48

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Espressif Systems
ESP8266EX
Hardware User Guide
Figure 8 ESP8266EX RF
2.2.6. External Resistor 12K
An external resistor that is connected to the ground should be added to ERS12K pin (Pin31), so as to
control the bias current in the circuit. Therefore, relatively high resistance value accuracy is required,
an accuracy of 12K±1% is recommended.
Figure 9 External Resistor
2.3. Layout Design
PCB layout design of products using chipset ESP8266EX is demonstrated in this part. Hereto we
mainly focus on two kinds of designs, one is ESP-WROOM serial to WiFi modules, and the other is
main board mounted with ESP8266EX WiFi module.
2.3.1. ESP-WROOM Module Design
• Module layout design and the key techniques:
This printed circuit board has four layers.
Espressif Systems / Jun 1, 2015 17 48