A display driving circuit includes a first interface unit, a signal discriminating circuit, a signal distributing circuit, a driver logic circuit and a synchronization processing unit. The first interface unit receives a first signal through a first interface from a host. The signal discriminating circuit discriminates whether the first signal corresponds to a first video signal or a second video signal. The signal distributing circuit divides the first signal into the first and second video signals based on a discrimination result of the signal discriminating circuit. The driver logic circuit drives a first display panel based on the first video signal. The second interface unit converts the second video signal into a second signal and provides the second signal through a second interface to an external display device. The synchronization processing unit receives a synchronization signal from the external display device and provides the synchronization signal to the host.