Reference Design For Power Supply - Quectel EC21 Series Hardware Design

VBAT
C1
D1
5.1V 100uF

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 is capable of providing sufficient current up to 2A at least. If the voltage
drop between the input and output is not too high, it is suggested that you should use an LDO 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. The typical output of the power
supply is about 3.8V and the maximum load current is 3A.
DC_IN
470uF 100nF
NOTE
In order to avoid damaging internal flash, please do not switch off the power supply when the module
works normally. Only after the module is shut down by PWRKEY or AT command, the power supply can
be cut off.
EC21_Hardware_Design
+
C3 C4
C2
100nF 33pF 10pF 100uF
Figure 8: Star Structure of the Power Supply
MIC29302WU
2
IN
51K
4.7K
VBAT_EN
47K
Figure 9: Reference Circuit of Power Supply
+
C5
C6 C7 C8
100nF 33pF 10pF
4
OUT
100K
1%
47K
1%
Confidential / Released
LTE Module Series
EC21 Hardware Design
VBAT_RF
VBAT_BB
Module
VBAT
470R
470uF
100nF
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