A power tool includes a brushless DC motor housed inside an upper body of the tool housing and a control unit housed inside a handle of the housing, the control unit including a micro-controller mounted on a control circuit board, a power unit electronically coupled to the micro-controller and mounted on a power circuit board arranged substantially parallel the control circuit board inside the handle, and a heat sink in thermal contact with the power unit. An input unit may be mounted directly on the control circuit board. An upper portion of the heat sink extending towards the upper body of the housing may include a tab protruding underneath a fan assembly of the motor to transfer heat from the power unit to the airflow created by the fan.