Patent ID: 7598510

Claim:
A serial interface connecting circuit comprising: a first Integrated circuit (IC) with a signal transmitting terminal and a signal receiving terminal; a second IC with a signal receiving terminal and a signal transmitting terminal; and a connecting circuit coupled between the first and second ICs for transmitting electrical signals between the first and second ICs, the connecting circuit comprising a first photocoupler having a first luminous element and a first optical receiving block, and a second photocoupler having a second luminous element and a second optical receiving block, an anode of the first luminous element being coupled to a first power source, a cathode of the first luminous element being coupled to the signal transmitting terminal of the first IC, a collector of the first optical receiving block being coupled to a second power source and the signal receiving terminal of the second IC, and an emitter of the first optical receiving block being coupled to ground; an anode of the second luminous element being coupled to a second power source, a cathode of the second luminous element being coupled to the signal transmitting terminal of the second IC, a collector of the second optical receiving block being coupled to the first power source and the signal receiving terminal of the first IC, an emitter of the second optical receiving block being coupled to ground.