Rtc (Optional); Esp32 Crystal Oscillator - Espressif Systems ESP32 Series Hardware Design Manuallines

2. Schematic Checklist and PCB Layout Design
Notice:
• If an oscillator is used, its output should be connected to XTAL_P on the chip. Please make sure that the oscillator
output is stable and its accuracy is within ± 10 ppm. It is also recommended that the circuit design for the oscillator
is compatible with the use of crystal, in case that if there is a defect in the circuit design, users can still use the
crystal.
• Defects in the craftsmanship of the crystal oscillators (for example, frequency deviation more than ±10 ppm) and
unstable operating temperature may lead to the malfunction of ESP32, resulting in a decrease of the overall per-
formance.

2.1.4.2 RTC (Optional)

4 8
GND VCC
ESP32 supports an external 32.768 kHz crystal or an external 32.768 kHz signal (e.g., an oscillator) to act as the
RTC sleep clock.
Figure 6 shows the schematic for the external 32.768 kHz crystal.
Espressif Systems
48
CAP1
47
CAP2
46
VDDA
45
XTAL_P
44
XTAL_N
43
VDDA
42
GPIO21
41
U0TXD
40
U0RXD
39
GPIO22
Figure 5: ESP32 Crystal Oscillator
C22 TBD
GND
U4
32.768KHz
C23 TBD
GND
Figure 6: Schematic for ESP32's External Crystal (RTC)
1
XIN GND
2
GND XOUT
VDET_1
GPIO35 11
VDET_2
GPIO32 12
32K_XP
GPIO33 13
32K_XN
GPIO25 14
GPIO25
R4 U2
TBD
6 ESP32 Hardware Design Guidelines V2.7
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