Wich is the Difference between VBATT and VBATT_PA?

2 thoughts on “Wich is the Difference between VBATT and VBATT_PA?”

1. Hello guys,

    

   I know is the most simple and ridiculous question, but have my doubts and I dont like the idea to have a failing module, only for a bad power supply.

    

   I saw the EVK2 schematics and for the HE910 and GE910 , the VBATT pin and VBATT_PA pin has connected by separated the bypass circuit. Then for me the power supply for VBAT and VBATT_PA are two different source.  But, the hardware user guide says
    " The external power supply must be connected to VBATT and VBATT_PA signals"
   "VBATT—> basebad"
   "VBATT_PA—>Radio PA"

   So, my conflict is about the information absence for the Radio PA. Because, why it has to be called VBATT and VBATT_PA if it has to be connected at the same source?

    

   Why is has two different bypass circuit? Is because you have to think these two pin like two different ICs even you have only one module? 

    

   I didn’t find the answer on the documentation for the HE910 and GE910. 

   Is a trite question but I prefer ask for a opinion and help. 

    

   Thank you for your time. 

    

    

   1. Hi,
      The VBATT_PA internally to the module is connected to Radio PA (Power Amplifier:  is this part that during the GSM transmission it absorb the 2A peak current) while the VBATT is connected internally to baseband part (this part has a current consumption much lower).
      The two Power Supply lines are separated because in some Designs the VBATT_PA could be connected directly to Li-Ion battery while on the VBATT line it places a low power MOSFET for having the chance to exclude completely the baseband part and so it saves as much possible the battery; moreover in this manner we haven’t the voltage drop on MOSFET during the 2A peak current.
       
      BR
      Bruno