Reference Design For Power Supply; Monitor The Power Supply - Quectel LTE-A Series Hardware Design

LTE-A Module Series
EG18 Hardware Design

3.5.3. 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 of EG18 should be able to provide sufficient current up to 2A at least. If
the voltage drop between the input and output is not too high, an LDO is suggested to 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 +5V input power source. In this design, output of the
power supply is about 3.8V and the maximum load current is 3A.
MIC29302WU
DC_IN VBAT
2 4
IN OUT
100K
1%
51K
470R
4.7K
470μF 100nF
470μF 100nF
47K
VBAT_EN
47K
1%
Figure 10: Reference Circuit of Power Supply
NOTE
To avoid damages to the internal flash, please do not switch off the power supply directly when the
module is working. Only after the module is shut down by PWRKEY or AT command can the power
supply be cut off.

3.5.4. Monitor the Power Supply

AT+CBC command can be used to monitor the voltage value of VBAT_BB. For more details, please refer
to document [3].
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