I'm working on a device that meters the flow of water and logs it to a WebAPI server, built around ESP32, using hall-effect sensors to monitor the flow. It's nearly done, but I still need to solve one problem.. The flow sensors need 5V to operate (4.3V bare minimum.) The device has a PV panel that charges its 18650 battery, which is perfect for every aspect of this circuit except the hall-effect flow sensors.
I have a buck converter to power the flow sensors, and a level converter to interface them to ESP32 GPIOs, but the buck converter uses power whenever it is on, regardless of whether there is any load, so I can't leave it powered up in a stand-by state. The CPU waits in a low power state for a single pulse from any sensor to wake it up, then it powers up the buck and from there the circuit works exactly as intended.
The problem is providing the sensors with 5V, without which the wake up pulse will never happen. I artificially sourced the sensors to test the rest of the circuit on the bench, but obviously that won't work in the wild.
Now for my actual question: isn't there a way to charge one or more capacitors, from 3.7V input, that would provide 5V discharge for just one pulse, when a sensor draws power (because it is spinning)? That would not burn power (after charging the cap) in stand-by? Is that feasible, or do I need to redesign my power supply, adding a second PV and battery (which will completely blow out my form factor and costs, but would give me workable voltage)?
I have a buck converter to power the flow sensors, and a level converter to interface them to ESP32 GPIOs, but the buck converter uses power whenever it is on, regardless of whether there is any load, so I can't leave it powered up in a stand-by state. The CPU waits in a low power state for a single pulse from any sensor to wake it up, then it powers up the buck and from there the circuit works exactly as intended.
The problem is providing the sensors with 5V, without which the wake up pulse will never happen. I artificially sourced the sensors to test the rest of the circuit on the bench, but obviously that won't work in the wild.
Now for my actual question: isn't there a way to charge one or more capacitors, from 3.7V input, that would provide 5V discharge for just one pulse, when a sensor draws power (because it is spinning)? That would not burn power (after charging the cap) in stand-by? Is that feasible, or do I need to redesign my power supply, adding a second PV and battery (which will completely blow out my form factor and costs, but would give me workable voltage)?