SIM800L powering issue - need to go from 5V to 4V
Hello. For a project I'm making, I need to power a SIM800L module having a 5V source power. I'm having trouble finding a way to get a stable 4V from the 5V source.
In case you're not familiar with the SIM800L:
- Vin: 3.4V-4.4V.
- The ideal voltage is 4V
- It is not recommended to use a voltage too close to the minimum voltage, so the actual Vin can be ~3.8V-4.4V
- Vin must be stable (or else RF communication will be noisy)
- Operating current: 15mA-30mA
- Sleep Mode current: 1mA-2mA
- Peak current: 2A
- They occur when the SIM800L is transmiting
- They can be as short as 0.5ms (text messages) as well as 2 whole seconds (phone calls), and are abrupt.
I already have a decoupling capacitor of 2200uF for the SIM800L, which I'm sure will help with the short bursts, but I think it won't with the 2-second peak currents, right?
I researched about voltage dividers, diodes in series, LDOs and buck converters. But they either vary their voltage too much with the change of current, require a high voltage dropout (1.5V or more) or are too slow for the sudden bursts.
Is there any way to go from 5V to (stable) 4V with such a variable current?
I'd like to avoid using a step-up, since my power source can stand up to 3A and I also need to reduce the current consumption as much as possible
PD: my power source is a charger module of 2 18650 1s batteries with an output of 5V@3A. It doesn't have an output with the actual voltage of the batteries. I need to use the charger module because I need it as a UPS for my project. Haven't found any better alternative in my country. I cannot do one myself since I'm not that good at making circuits and I could end up burning the LiPo batteries (unless it's actually easy... which I'm sure it's not.......)
English is not my first language so sorry if it's a bit unclear.