Reference Design For Power Supply; Monitor The Power Supply; Power-On/Off Scenarios; Turn On Module Using The Pwrkey - Quectel EG91 Series Hardware Design

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
470 μF 100 nF
NOTE
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.
EG91_Series_Hardware_Design
MIC29302WU
2
IN
51K
4.7K
VBAT_EN
47K
Figure 9: Reference Circuit of Power Supply
LTE Standard Module Series
4
OUT
100K
1 %
470R
47K
1 %
VBAT
470 μF
100 nF
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