A universal input buffer has a pair of input pins. A first input of a multiplexer is coupled to the second input pin and a second input of the multiplexer receives a common mode voltage of a differential signal applied to the first pin. The multiplexer is responsive to a selection signal to select either of the first and second inputs of said multiplexer. A pair of single-input buffers have inputs coupled respectively to the first and second input pins. A first input of a first differential buffer is coupled to the first input pin, a first input of a second differential buffer is coupled to the second input pin, the second input of the first differential buffer is coupled to the output of the multiplexer, and the second input of the second differential buffer receives a common mode voltage of a differential signal applied to the second pin.