Do you have anything that needs 5V or can you run everything at 3.3V?Is it possible to use 2 batteries, so you can step down from 7V?
Bad idea. That boost converter may be quite efficient (losing just 10-15%) but your linear regulator loses 34% no matter what. That's nearly half the energy of your battery being converted to heat, instead of doing something useful for you.There exist boost/buck converters that can go both ways. That may be a solution. I was actually quite surprised to see the SIM7600 not being able to run directly off a 3.7V battery, many GSM adapters are designed to do just that.Looking at the datasheet of the MIC29302 it looks like the drop-out is low enough to have it run directly from your battery. No need for the boost converter.The thing is, most of your components will not draw much power normally, just spikes. Check the actual power consumption. You may be able to get it done with the MCP1700 and a big-ass capacitor (maybe even a small supercap) to support the spikes on the 3.3V side. I'm thinking of a capacitance in the order of 1-100 mF (that's m, not µ).
Yes I know (but I am not expert) that Linear Regulator are not good for a battery powered project. But the 5Volt sensor actually is a big problem, with output of 0.5 to 4.5 volts.
To avoid lose a lot of power I will control the modules power on/off using a load switch from MCU.
the SIM7600 need 3.8V recommended
ATMega2560 use 5V,
Which exact sensor is that? No 3.3V version or replacement of it?Use the Enable pin of modules when available.The SIM7600 datasheet that I found says it needs 3.0-3.6V. Apparently it's designed for 3.3V operation. The capacitor would have to deal with the current spikes.SD cards can also be pretty power hungry.Why not a 328p? I don't see any reason for the 2560 based on your component list. The ATmega328p runs fine on 3.3V, 8 MHz. At that speed it runs at anything from 2.4V up to 5.5V.
Which exact sensor is that? No 3.3V version or replacement of it?
I dont have two chances to pay a PCBA services.
I would like to test before but I dont have arduino, neither modules . I only have a reference circuits of IC manufacturers and my laptop :/
Are you suggesting you want to design a 'project' and put it on a PCB or whatever, but that you are unable or unwilling to actually test it ?