Reference Material - Holtek HT32 Manualline

2. After a reset, the internal pull-up resistor on the BOOT pin will be enabled by default. Here the
resistor value is about 46kΩ. Refer to the datasheet for the specific value.
Based on the above two points, the following notes should be considered:
 If the BOOT pin is not pin-shared with other functions, it can be left unconnected. However,
it is recommended to externally connect it to a resistor to reduce any ESD/EFT influences.
 The BOOT pin can be used as an output pin. Considering that a WDT Reset or an NVIC
Reset executes rapidly, the BOOT pin voltage rise rate may be insufficient if it is only
relying on the internal pull-up resistor. In order to prevent the MCU from entering the ISP
BootLoader or SRAM by mistake, an external 4.7kΩ pull-up resistor connected to the
MCU's VDD pin should be connected.
 The BOOT pin should not be used as an input unless it is certain that the BOOT or BOOT1
pin will have a logic "1" condition after a reset.
Layout Consideration
 Avoid placing power lines beneath the MCU. Additionally, DGND and the high frequency
output lines should retain a certain distance from each other and not be parallel to each other to
avoid coupling interference. Also high current power lines should be kept at a certain distance
from both the MCUs DGND and VDD lines to avoid coupling interference.
 The power lines should not be routed on the edge of the PCB to avoid EMI influence.
 A magnetic bead should be added between the digital power and the analog power lines for
isolation purposes.
Conclusion
For designers who are using the HT32 MCUs for the first time, this application note can assist them
to more rapidly design safe and stable hardware requiring reduced revisions.

Reference Material

For more information, refer to the Holtek official website: http://www.holtek.com.
AN0630EN V1.00
HT32 MCU Hardware Development Guideline
11 / 12 December 15, 2022