Give Any I2C Device a Low-Power Mode with This ATtiny-Based Board

Power management challenges

The day-to-day electronic devices we interact with are typically powered in one of two ways: either through a wall outlet connection or via a lithium-based battery. In the second case, ensuring the device does not overconsume energy is vital to maintaining proper temperatures, minimizing costs, and most importantly, operating for a long time between charge cycles.

Partially inspired by the more advanced power management integrated circuits (PMICs) that are already a part of many portable electronics, Platima from the YouTube channel Platima Tinkers wanted to design his own version that would cost less and could be used with a variety of devices externally.

Cutting power

Most microcontrollers and microprocessors, such as the Arm Cortex-M series all the way up to thousand-dollar CPUs, have some form of built-in sleep functionality that shuts down unnecessary processing and waits until a signal has been received to wake back up. But in Platima's design, the module removes the connection to power entirely until the requested amount of time has passed, after which the connection is enabled again and reboots the attached device.

The PCB he had fabricated achieves this functionality through several connectors. First, a USB-C port accepts 5V at up to 3A, which is then passed to an N-channel MOSFET before heading to the device over another USB-C port. When the ATtiny414 receives the shutdown command, it toggles one of its GPIO outputs and stops the flow of power through the MOSFET.

Other features

With this configuration, Platima's DeepSleepr can achieve a quiescent current draw of merely 5uA when the external device is in the deep sleep mode. And although the code only supports I2C control at the moment, the PCB's SPI headers will allow for a new communication mode to be added at a later date.