Tindarian Embedded Loop has been working on a solar powered air quality sensing device, which features LoRaWAN and Bluetooth LE for communication, as well as a LiPo battery pack to keep it running when the sun isn’t out. To power things, he needed a 5V boost converter for this limited power supply, but according to ‘Loop: “Most boost converters only switch off the boost function itself when they are disabled, still allowing current to flow through to the output via the inductor and the diode”.
To avert unneeded current drain, he designed this breakout board using the (currently widely available) FP6277 chip, which switches the power output on or off based on an enable pin. This type of operation is perfect for a remote sensor rig, and this particular breakout provides 5V, and up to 800mA as needed.
When in shutdown mode, the converter’s quiescent current is under 1uA, that is, less than 1 microampere, or 0.000001 amp. That means that a small 100 mAh battery would theoretically take over 100,000 hours to drain under these conditions. On the other hand, if the sun doesn’t come out in that time (11+ years), air quality monitoring is likely the least of your concerns!
