An electronic control circuit with a backup energy source subassembly for an e-latch assembly and a method of operating the backup energy source subassembly are disclosed. The electronic control circuit includes a control unit including a computing module and a memory for electrically coupling to a plurality of sensors and to a main power source. The backup energy source subassembly is electrically coupled to the control unit for providing electrical energy to the electronic control circuit in response to one of a failure and interruption of the main power source. An output module is electrically connected to the backup energy source subassembly and to the main power source for driving an actuation group. The backup energy source subassembly includes a backup low voltage source and a boost-buck converter configured to selectively supply voltage to and selectively amplify voltage from the backup low voltage source.