I've been working on getting the deep sleep current for the StickC Plus as low as possible. When powered via the StickC's internal battery, I can get the deep sleep current draw to about ~1ma.
However, whenever I power the StickC (or the Atom) via the USB-C connector, I can never get the deep sleep current draw to go any lower than 16mA.
Looking at the StickC schematic, I see that the USB-C IC and the USB to UART IC are always powered when USB is connected. I also see two resistor dividers for the ESP32_EN and GPIO0 signals which are also powered by VBUS_USB. The resistor dividers alone will cause a constant ~5mA current draw, so I assume the rest is coming from the other two IC's.
This is an issue as all of the M5 products that provide an external battery (TailBat, 18650C) appear to all provide power via the USB-C connector. This means that by just adding an external battery, you're adding an additional constant 15mA current draw, which kind of defeats the purpose for low power applications. The only way I've found around this is using the 5V input pin on the StickC, but that doesn't exist for the Atom.
Has anyone had any luck reducing the current draw when powered via USB-C?