The ATtiny43U boost converter automatically starts when a fresh battery is applied or a charger is connected to the system. The start-up voltage is 1.2V. The maximum load current that the regulator delivers is 60mA from a fresh battery. In case a disposable battery is used, it is often desirable to use all the available energy in the battery. ATtiny43U will work until the battery voltage drops down to 0.7V. This is lower than any other similar microcontroller can go, and will effectively drain the battery. On the other hand, if the system uses a re-chargeable battery, there is an option to switch off the boost converter and the chip at higher battery levels to avoid battery damage. The on chip ADC can accurately measure the battery voltage and the software can decide when to shut off. The operation of the boost converter requires a similar set of passive components that are used with any typical DC-DC converter.