Usb_Boot Interface - Quectel EC21 Series Hardware Design

3.19. USB_BOOT Interface

EC21 provides a USB_BOOT pin. During development or factory production, USB_BOOT pin can force
the module to boot from USB port for firmware upgrade.
Table 23: Pin Definition of USB_BOOT Interface
Pin Name Pin No.
USB_BOOT 115
The following figure shows a reference circuit of USB_BOOT interface.
EC21_Hardware_Design
I/O Description
Force the module to boot from USB
DI
port
Module
USB_BOOT
TVS
Figure 30: Reference Circuit of USB_BOOT Interface
Test point
10K
Close to test point
Confidential / Released
LTE Module Series
EC21 Hardware Design
Comment
1.8V power domain.
Active high.
If unused, keep it open.
VDD_EXT
57 / 94