ram soldered in systemboard

Hello everyone. I have lenovo ideapad s340-14IWL with Model Name:81N7 This laptop comes with built-in RAM (soldered in systemboard) or (in motheboard) and it’s only 4gb, 2400MHz. there is only one free slot available for RAM upgrade, Now i went to see the specifications of the built-in RAM so...

I have lenovo ideapad s340-14IWL MODEL NUMBER: 81N7 It has 4gb built-in with the motherboard and a free slot to upgrade. Now i want to know the CAS Latency and voltage it uses to buy a RAM with same specifications. I couldn’t figure out, i even contacted lenovo and they said they can’t check CAS...