External Resistor 12K; Layout Design; Esp-Wroom Module Design - Espressif Systems ESP8266EX Hardware User's Manual

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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.
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.
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Figure 8 ESP8266EX RF
Figure 9 External Resistor
17 48 /
ESP8266EX
Hardware User Guide
Jun 1, 2015