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HW Bring UP Part II: RTC LOW POWER GATING

A project log for LowPow E-Ink ShortKeyboard BLE, Wired, LoRa,Wifi

A Ultra Low Power Shortcut Eink Keyboard that works on Bluetooth or Wired. With Wifi, LoRa, SD Card, Joystick, Rotary Volume Knob

UlrichUlrich 06/19/2022 at 15:020 Comments

You might remember: I always planned to have a very low quiescent current.

Most of the time your shortcut keyboard sits around and is doing nothing.

Some says ago i stumbled over this TPL5110 Module on Adafruit. This is an excellent idea to get more out of your battery if you really want to get the most jucie of your battery.

Basically it cuts the complete Power of your circuit after a while and only needs 50 nA(Yes Nano Amps).-.-. This is way less than any Microcontroller in sleep mode.

Schematics:

So time to bring this part of the PCB to live:

You can see in this video: In Low Power Mode my Multimeter can not measure any current. Once started by a keypress the complete board starts up.. the ESP32 starts and the board consumes 125 mA(average due to wifi activity)

Once the Mikrocontroller has done all its jobs it sends a shutdown Signal to the TPL5110 on the DONE pin.... This Shuts down the Power Supply and the low current time starts.

If there is no DONE Signal sent by the Mikrocontroller an automatic shutdown is performed

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