Service Guide

LTE Standard Module Series
EG91_Series_Hardware_Design
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3.6.3. Reference Design for Power Supply
Power design for the module is very important, as the performance of the module largely depends on the
power source. The power supply should be able to provide sufficient current up to 2 A at least. If the
voltage drop between the input and output is not too high, it is suggested that an LDO should be used to
supply power for the module. If there is a big voltage difference between the input source and the desired
output (VBAT), a buck converter is preferred to be used as the power supply.
The following figure shows a reference design for +5 V input power source. The typical output of the
power supply is about 3.8 V and the maximum load current is 3 A.
DC_IN
MIC29302WU
IN OUT
EN
GND
ADJ
2 4
1
3 5
VBAT
100 nF
470 μF
100 nF
100K
47K
470 μF
470R
51K
1 %
1 %
4.7K
47K
VBAT_EN
Figure 9: Reference Circuit of Power Supply
To avoid damaging internal flash, do not switch off the power supply when the module works normally.
Only after the module is shut down by PWRKEY or AT command, then the power supply can be cut off.
3.6.4. Monitor the Power Supply
AT+CBC can be used to monitor the VBAT_BB voltage value. For more details, refer to document [3].
3.7. Power-on/off Scenarios
3.7.1. Turn on Module Using the PWRKEY
The following table shows the pin definition of PWRKEY.
NOTE