The DisplayPort interface uses an LVDS signal protocol that is not compatible with DVI or HDMI. However, dual-mode DisplayPort ports are designed to transmit a single-link DVI or HDMI protocol (TMDS) across the interface through the use of an external "passive" adapter. This adapter enables compatibility mode and converts the signal from 3.3 to 5 volts. For analog VGA/YPbPr and dual-link DVI, a powered "active" adapter is required for compatibility and does not rely on dual mode. Active VGA adapters are powered by the DisplayPort connector directly, while active dual-link DVI adapters typically rely on an external power source such as USB.