Rtc Clock(Optional); Schematic For The Rtc Clock - Espressif Systems ESP32-H2 Series Hardware Design Manuallines

2 Schematic Checklist
• When Bluetooth connection fails, after ruling out software problems, you may follow the steps mentioned above to
ensure that the frequency offset meets the requirements by adjusting capacitors at the two sides of the crystal.

2.4.2 RTC Clock(optional)

ESP32-H2 supports an external 32.768 kHz crystal or an external signal (e.g., an oscillator) to act as the RTC
sleep clock. Using an RTC clock is aimed at achieving more accurate timekeeping and reducing average power
consumption, and does not have impact on the functionality.
Figure 6 shows the schematic for the external 32.768 kHz crystal.
Notice:
• Please note the requirements for the 32.768 kHz crystal.
– Equivalent series resistance (ESR) ⩽ 70 kΩ.
– Load capacitance at both ends should be configured according to the crystal's specification.
• The parallel resistor R is used for biasing the crystal circuit (5 MΩ < R ⩽ 10 MΩ). In general, you do not need to
populate the resistor.
• If the RTC clock is not required, then the pins for the external 32.768 kHz crystal can be used as other GPIOs.
2.5 RF
The RF circuit of the ESP32-H2 series of chips is mainly composed of three parts, the RF traces on the PCB
board, the chip matching circuit, the antenna and the antenna matching circuit.
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• For the RF traces on the PCB board, 50 Ω impedance control is required.
• For the chip matching circuit, it must be placed close to the chip. It is mainly used to adjust the impedance
point and suppress harmonics. The CLC structure is preferred, and a set of LC can be added if space
permits. The CLC matching circuit is shown in Figure 7.
• For the antenna and the antenna matching circuit, to ensure the radiation performance, the antenna's
characteristic impedance must be around 50 Ω. Adding a CLC matching circuit near the antenna is
recommended to adjust the antenna. However, if the available space is limited and the antenna impedance
point can be guaranteed to be 50 Ω by simulation, then there is no need to add a matching circuit near the
antenna.
Espressif Systems
C13 TBD
GND
GPIO13
X1
GPIO14
32.768kHz
GND
C14 TBD
Figure 6: Schematic for the RTC Clock
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9
VDDPST1
10
GPIO8
11
GPIO9
12
GPIO10
13
GPIO11
14
GPIO12
15
XTAL_32K_P
16
XTAL_32K_N
3
ESP32-H2 Series Hardware Design Guidelines v0.5
U1
ESP32-H2
GND
33
GND
32
ANT
31
VDD3P3
30
VDD3P3
29
XTAL_P
28
XTAL_N
27
VDD3P3
26
GPIO27
25
GPIO26
2