The TPL5110 Nano Power Timer is ideal for applications that require low power, and especially those projects that are running off of a LiPo battery. The Nano Power Timer will turn on your project, most likely a microcontroller, after the set amount of time, continuously. When your microcontroller has completed whatever needs doing, sampling air quality for example, it can then signal back to the Nano Power Timer to turn it off. While the project is off, the Nano Power Timer will only consume 35nA of power until the timer turns the project back on again.
The Nano Power Timer can handle voltages between 1.8V and 5.5V as well as current up to 1.1A with times from 100ms to two hours. The TPL5110 delay is configured with the use of resistors. A six-way DIP switch is added to select one of the five preinstalled resistors.
More information is available on the website of Sparkfun.