In a rapidly changing world, vendors need to modernize and upgrade their products. Existing designs can be too bulky, consume too much energy and offer features that are out of date. These upgrades often imply a need for a small microcontroller. A torch or a flashlight is an example of a product that is familiar to us all. In the current, 50-year-old design, it’s common to find an energy-wasting light bulb inside the torch or flashlight. A better alternative is to use high-brightness LEDs that give superior luminance at the same energy level. But there is a drawback: LEDs need higher voltage, which calls for more batteries. This increases the size, weight and cost of the torch. The solution is to use a boost converter circuitry controlled by an MCU. This results in a lighter, more attractive design that is preferred by users. The additional benefit is ”an everlasting” LED bulb. Using a tinyAVR® MCU, in this case ATtiny43U, the customer can go with one battery only (at 1.5 V) and boost up the voltage level sufficiently high for the high-brightness LED. The MCU can provide additional functionality, like brightness control, programmed flash sequences, timer for shut down, etc. The manufacturer gains flexibility to easily apply product customization, adding features by changing the software only.