My circuit is a sensor logger to WebAPI based on ESP32. Throughout the evolution of my ESP projects I've been using LDOs like the REG1117 to get 3V3 for the SoC. This worked for the most part, but became problematic when I started using LiPo batteries like the 18650. When the LiPo discharges down to the lower range of its output voltage, it's lower than the minimum required by the LDO in order to maintain 3V3. So at 3.9V battery the LDO output is 2.9, which is below the SoC's minimum, but enough for it to try to boot up. It goes into a continuous brownout error->reboot cycle, that over-discharges the battery.
I used a voltage divider and the ADC to detect the battery voltage, and at a certain level force it into a deep sleep until the PV recharges the battery. But even so, it underutilizes the full charge capacity of the LiPo, and though it greatly delays/reduces chances of any brownout death cycle, it doesn't preclude it.
My search for a better power solution led me to the Torex boost LDO, XC9261B33DER-G, which claims to be able to output 3V3 from a single AAA cell. It seems to be perfect for LiPo output voltage range and meets all my other requirements except for one: I can't get the damn thing to bloody work! The output voltage is the same as input. I tested for continuity between nets on a bare board, there is none.
The first image is my old tried and true power circuit. #2 is the schematic, #3 is the board CAD.
One glaring problem is the tiny wire going from the Schottky diode to the inductor, I forgot to make it wider again after a rip-up. But I soldered a piece of wire in to correct it, even tried bypassing the diode, didn't change anything. I'm about ready to give up and go back to my inadequate but working power component... a downside of going all SMD is it makes breadboard tests all but impossible.
If anyone has any insight, knowledge -- hell, even wild guesses at this point would be appreciated.
TIA.
I used a voltage divider and the ADC to detect the battery voltage, and at a certain level force it into a deep sleep until the PV recharges the battery. But even so, it underutilizes the full charge capacity of the LiPo, and though it greatly delays/reduces chances of any brownout death cycle, it doesn't preclude it.
My search for a better power solution led me to the Torex boost LDO, XC9261B33DER-G, which claims to be able to output 3V3 from a single AAA cell. It seems to be perfect for LiPo output voltage range and meets all my other requirements except for one: I can't get the damn thing to bloody work! The output voltage is the same as input. I tested for continuity between nets on a bare board, there is none.
The first image is my old tried and true power circuit. #2 is the schematic, #3 is the board CAD.
One glaring problem is the tiny wire going from the Schottky diode to the inductor, I forgot to make it wider again after a rip-up. But I soldered a piece of wire in to correct it, even tried bypassing the diode, didn't change anything. I'm about ready to give up and go back to my inadequate but working power component... a downside of going all SMD is it makes breadboard tests all but impossible.
If anyone has any insight, knowledge -- hell, even wild guesses at this point would be appreciated.
TIA.