Product Info

LTE Standard Module Series
EG91 Series Hardware Design
EG91_Series_Hardware_Design 56 / 106
V
IL
≤
0. 5V
V
H
=0.8V
VBAT
PWRKEY
≥
500ms
RESET_N
VDD_EXT
About 100ms
USB_BOOT
USB_BOOT can be pulled up to 1.8V before
VDD_EXT Is powered up, and the module will
enter emergency download mode when it is
powered on.
NOTE 1
Figure 29: 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 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 28 can manually force the module to enter download mode.
NOTES