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LTE-A Module Series
EG18 Hardware Design
EG18_Hardware_Design 68 / 104
“*” means under development.
3.20. USB_BOOT Interface
EG18 provides a USB_BOOT pin. Developers can pull up USB_BOOT to VDD_EXT before powering on
the module, to make the module enter into emergency download mode when powered on. In this mode,
the module supports firmware upgrade over USB interface.
Table 29: Pin Definition of USB_BOOT Interface
The following figure shows a reference circuit of USB_BOOT interface.
Module
USB_BOOT
VDD_EXT
10K
Test Point
TVS
Close to module
Figure 35: Reference Circuit of USB_BOOT Interface
GPIO_5
172
IO
If unused, keep it open.
VDD_RF
162
PO
Provide 2.85V for external RF circuit.
If unused, keep it open.
Pin Name
Pin No.
I/O
Description
Comment
USB_BOOT
140
DI
Force the module to enter into
emergency download mode
1.8V power domain.
Active high.
If unused, keep it open.
NOTE