I will use a SIM300C Module for a project. I read datasheet and some another documents about SIM300 but i can't understand about VDD_EXT pin.
1) I don't need VDD_EXT functitons so can i leave it floating?
2) Do i have to connect to VDD_EXT pin with a LDO?
3)
There are two functions of VDD_EXT
1. You can check your system is working or not. If voltage is HIGH at pin means module is working.
2. You can give supply of 3.0V to external citcuit. This is not often used.
If you don't want to use you can leave it floating...