Product Info

LTE Standard Module Series
EC25 Series Hardware Design
EC25_Series_Hardware_Design 70 / 134
Module
USB_BOOT
VDD_EXT
4.7K
Test points
TVS
Close to test points
Figure 31: Reference Circuit of USB_BOOT Interface
VBAT
PWRKEY
RESET_N
VDD_EXT
USB_BOOT
USB_BOOT can be pulled up to 1.8 V before
VDD_EXT Is powered up, and the module will
enter emergency download mode when it is
powered on.
NOTE 1
≥ 500 ms
V
IL
≤ 0.5 V
V
H
= 0.8 V
About 100 ms
Figure 32: Timing Sequence for Entering Emergency Download Mode
1. Please 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.
NOTES