Newbie quesitons before build my own custom ARDUINO MEGA 2560

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6

OK I understand most of my question while I'm waiting the answer I make search for it but now I have question,

Freaduino Mega2560 use PMIC - Voltage Regulators - DC DC Switching Regulators
It's "MP2307"

I don't know what is the difference between it and the one used in MEGA 2560
PMIC - Voltage Regulators - Linear

It's "NCP1117ST50T3G"

from this link

http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-voltage-regulators-dc-dc-switching-regulators/2556570?k=mp2307

I could understand that switching regulator have frequency and variable output voltage
It could provide 5V DC with 2000mA output current but why it use many pins unlike linear regulator which 4 pins only,

I need 2000mA output current with pure 5V DC, what about using one of these chip

http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-voltage-regulators-linear/2556290?k=&pv129=13&FV=c00001%2C1fc11fd%2C2040001%2C2040006%2C2040007%2C204000d%2C2040068%2C204008f%2C20400a0%2C20403ab%2Cfff40027%2Cfff80182%2C1140003&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

I'll use Two 9V battery (everyone 500mA) and connect them in parallel mode to get 1000mA 9V DC and the use one of those 3A 5V PMIC - Voltage Regulators - Linear to convert it to 5v but my question this time is will this be safe for the circuit and PCB board is their heat if i use 3A PMIC - Voltage Regulators - Linear

what about using Double 9V battery provide 1000mA is that enough to get 3A 5V from it

that's all my question hope this time one of those hundred visitors for my thread put some reply :slight_smile: ,

Kind Regards