Quectel EC25-AUX Hardware Design page 69

VBAT
PWRKEY
VDD_EXT
USB_BOOT
RESET_N
Figure 32: Timing Sequence for Entering Emergency Download Mode
NOTES
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 30ms.
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 1.8V before powering up VBAT.
Short the test points as shown in Figure 31 can manually force the module to enter download mode.
EC25_Hardware_Design
Module
USB_BOOT
TVS
Figure 31: Reference Circuit of USB_BOOT Interface
NOTE 1
≥500ms
V IL ≤0.5V
About 100ms
USB_BOOT can be pul led up to 1.8V before
VDD_EXT Is powered up, and the module will
enter emerge ncy download mode wh en i t is
powered on.
LTE Standard Module Series
VDD_EXT
Test point
4.7K
Close to test point
V H =0.8V
EC25 Hardware Design
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