Espressif Systems ESP32-S3 - Waterproof and Proximity Sensing Design; Typical Layout Problems and Solutions; 1. The voltage ripple is not large, but the TX performance of RF is rather poor.

Chapter 4. PCB Layout Design
• The trace should be as short as possible and no longer than 300 mm.
• The trace width (W) can not be larger than 0.18 mm (7 mil).
• The alignment angle (R) should not be less than 90°.
• The trace-to-ground gap (S) should be in the range of 0.5 mm to 1 mm.
• The electrode diameter (D) should be in the range of 8 mm to 15 mm.
• Hatched ground should be added around the electrodes and traces.
• The traces should be isolated well and routed away from that of the antenna.
Fig. 17: ESP32-S3 Sensor Track Routing Requirements
Note: For more details on the hardware design of the touch sensor, please refer to Touch Sensor Application Note.
4.10.3 Waterproof and Proximity Sensing Design
ESP32-S3 touch sensor has a waterproof design and features proximity sensor function. Figure ESP32-S3 Waterproof
and Proximity Sensing Design shows an example layout of a waterproof and proximity sensing design.
Note the following guidelines to better implement the waterproof and proximity sensing design:
• The recommended width of the shield electrode width is 2 cm.
• Employ a grid on the top layer with a trace width of 7 mil and a grid width of 45 mil (25% 󰝘ll). The 󰝘lled grid
is connected to the driver shield signal.
• Employ a grid on the bottom layer with a trace width of 7 mil and a grid width of 70 mil (17% 󰝘ll). The 󰝘lled
grid is connected to the driver shield signal.
• The protective sensor should be in a rectangle shape with curved edges and surround all other sensors.
• The recommended width of the protective sensor is 2 mm.
• The recommended gap between the protective sensor and shield sensor is 1 mm.
• The sensing distance of the proximity sensor is directly proportional to the area of the proximity sensor. How-
ever, increasing the sensing area will introduce more noise. Actual testing is needed for optimized performance.
• It is recommended that the shape of the proximity sensor is a closed loop. The recommended width is 1.5 mm.
4.11 Typical Layout Problems and Solutions
4.11.1 1. The voltage ripple is not large, but the TX performance of RF is rather poor.
Analysis: The voltage ripple has a strong impact on the RF TX performance. It should be noted that the ripple
must be tested when ESP32-S3 is in the normal working mode. The ripple increases when the power gets high in a
di󰝗erent mode.
Generally, the peak-to-peak value of the ripple should be <80 mV when ESP32-S3 sends MCS7@11n packets, and
<120 mV when ESP32-S3 sends 11 MHz@11b packets.
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