LTE Module SeriesEC21 Hardware DesignEC21_Hardware_Design Confidential / Released 34 / 94ModuleVBAT_RFVBAT_BBVBATC1100uFC6100nFC733pFC810pF++C2100nFC5100uFC333pFC410pFD15.1VFigure 8: Star Structure of the Power Supply3.6.3. Reference Design for Power SupplyPower design for the module is very important, as the performance of the module largely depends on thepower source. The power supply is capable of providing sufficient current up to 2A at least. If the voltagedrop between the input and output is not too high, it is suggested that you should use an LDO to supplypower 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 powersupply is about 3.8V and the maximum load current is 3A.DC_INMIC29302WUIN OUTENGNDADJ2 4135VBAT100nF 470uF 100nF100K47K470uF470R51K 1%1%4.7K47KVBAT_ENFigure 9: Reference Circuit of Power SupplyIn order to avoid damaging internal flash, please do not switch off the power supply when the moduleworks normally. Only after the module is shut down by PWRKEY or AT command, the power supply canbe cut off.NOTEQuectelConfidential
