Product Info
Table Of Contents
- About the Document
- Contents
- Table Index
- Figure Index
- 1 Introduction
- 2 Product Concept
- 3 Application Interfaces
- 3.1. General Description
- 3.2. Pin Assignment
- 3.3. Pin Description
- 3.4. Operating Modes
- 3.5. Power Saving
- 3.6. Power Supply
- 3.7. Power-on/off Scenarios
- 3.8. Reset the Module
- 3.9. (U)SIM Interfaces
- 3.10. USB Interface
- 3.11. UART Interfaces
- 3.12. PCM and I2C Interfaces
- 3.13. SPI Interface
- 3.14. Network Status Indication
- 3.15. STATUS
- 3.16. ADC Interface
- 3.17. Behaviors of RI
- 3.18. USB_BOOT Interface
- 4 GNSS Receiver
- 5 Antenna Interfaces
- 6 Electrical, Reliability and Radio Characteristics
- 7 Mechanical Dimensions
- 8 Storage, Manufacturing and Packaging
- 9 Appendix A References
- 10 Appendix B GPRS Coding Schemes
- 11 Appendix C GPRS Multi-slot Classes
- 12 Appendix D EDGE Modulation and Coding Schemes
LTE Standard Module Series
EG91 Hardware Design
EG91_Hardware_Design 51 / 93
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. I/O Description Comment
USB_BOOT 75 DI
Force the module to enter into
emergency download mode
1.8V power domain.
Active high.
It is recommended to
reserve test point.
The following figures show the reference circuit of USB_BOOT interface and timing sequence of entering
into emergency download mode.
Module
USB_BOOT
VDD_EXT
4.7K
Test point
TVS
Close to test point
Figure 28: Reference Circuit of USB_BOOT Interface