I am using the SIM900A GSM module which requires 3.2V to 4.8V with max current draw of 2A.
In my board, I have a 5V, 3A supply which will be used to power the SIM900A.
Generally, in my search I found 2 ways to power it:
- Use a LM317 regulator to produce around 3.9-4V
- Just simply use a high current series diode (like the 1N4007, with forward voltage = 0.6v) to produce 5V-0.6V = 4.4V
My question is Is there any advantage of 1 over 2 (or disadvantage of 2 over 1 for that matter) as 2. is much simpler and cheaper.
I want to use 2 if there shouldn't be any major disadvantage.
I have seen both in commercial Chinese SIM900A modules, so I guess there should not be any problem with 2. But then why use the LM317?