In my project, I am designing a board which is supplied by a battery. The battery is a LiPo, 3.7 V, 1000 mAh, so its voltage range is 3 - 4.2 V.
All the components on the board need a fixed voltage of 3.3 V. In some configuration the board can draw 1 A, but most of the time it draws about 50 mA.
I need to convert the battery voltage to 3.3 V. I was thinking of 3 options:
- Option 1. Using a buck-boost converter
- Option 2. Using a buck converter and electronically cut the power supply when it is approaching 3.3 V (let's say 3.6 V)
- Option 3. Same as option 2 but with an LDO
Do you see better options?
My conclusions are as follows:
- Option 1 is the most expensive option, and price does matter.
- All the 3.3 V buck converters I have found only accepts input voltages starting at 4 V. Is it a normal behavior that bucks need a voltage gap to work?
- Option 3 seems to be the best option. But when the board draws 1 A, I would need to dissipate maximum (4.2 V - 3.3 V) * 1 A = 0.9 W, which is too much because the board is very small so it would badly dissipate heat, and heat does matter...
Which options would you use in such a case? Do you have advice?