Usb_Boot Interface - Quectel EG91 Series Hardware Design

3.18. USB_BOOT Interface

EG91 provides a USB_BOOT pin. Customers can pull up USB_BOOT to VDD_EXT before powering on
the module, thus the module will enter into emergency download mode when powered on. In this mode,
the module supports firmware upgrade over USB interface.
Table 22: Pin Definition of USB_BOOT Interface
Pin Name Pin No.
USB_BOOT 75
The following figures show the reference circuit of USB_BOOT interface and timing sequence of entering
into emergency download mode.
EG91_Hardware_Design
I/O Description
Force the module to enter into
DI
emergency download mode
Module
USB_BOOT
TVS
Figure 28: Reference Circuit of USB_BOOT Interface
LTE Standard Module Series
VDD_EXT
Test point
4.7K
Close to test point
EG91 Hardware Design
Comment
1.8V power domain.
Active high.
It is recommended to
reserve test point.
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