The present invention relates to a line termination unit (1') comprising: - a line driver (10) for driving a transmission line, with a first supply voltage input terminal (11) and a second supply voltage input terminal (12); - a power supply means (20), with an analog supply voltage output terminal (22) for feeding an analog part of the line termination unit, and at least one digital supply voltage output terminal (23a, 23b, 23c) for feeding a digital part of the line termination unit, and - a ground voltage reference (30). In accordance with a first aspect of the invention, the analog supply voltage output terminal is coupled to the first supply voltage input terminal, and the line termination unit further comprises a selector (40) for selectively coupling one of the at least one digital supply voltage output terminal or the ground voltage reference to the second supply voltage input terminal.