Quectel EG21-G - Page 54

LTE Module Series
EG21-G Hardware Design
EG21-G_Hardware_Design 53 / 100
Figure 29: Timing Sequence for Entering into Emergency Download Mode
1. Please make sure that VBAT is stable before pulling down PWRKEY pin. The time between them is
no less than 30ms.
2. When using MCU to control module to enter into the forced download mode, follow the above timing
sequence. It is not recommended to pull up USB_BOOT to 1.8V before powering up the VBAT. Short
the test points as shown in Figure 32 can manually force the module to enter into download mode.
NOTES