LTE Standard Module Series
EC21_Series_Hardware_Design
68
/ 118
The following figure shows a reference circuit of USB_BOOT interface.
Module
USB_BOOT
VDD_EXT
4.7K
Test points
TVS
Close to test points
Figure 31: Reference Circuit of USB_BOOT Interface
Figure 32: Timing Sequence for Entering Emergency Download Mode
1. Make sure that VBAT is stable before pulling down PWRKEY pin. It is recommended that the time
between powering up VBAT and pulling down PWRKEY pin is no less than 30 ms.
2. When using MCU to control module to enter the emergency download mode, please follow the
above timing sequence. It is not recommended to pull up USB_BOOT to 1.8 V before powering up
VBAT. Connect the test points as shown in Figure 31 can manually force the module to enter
download mode.
NOTE
To Next Page
Loading...
Need help?
General
