The HEMSA-T-019 PCI converter card, compatible with RS-485 and RS-422 standards, is capable of converting single-ended PCI signals to balanced differential RS-485/RS-422 signals with a fast transient voltage suppressor protector, which is designed to protect RS-485/RS-422 interfaces with today's advanced TVS. Under normal conditions, the TVS tube is in a high resistance state. When the two ends of the TVS tube are subjected to an instantaneous high-energy shock, it can reduce the impedance at both ends at a very high rate and absorb large current, thus clamping the voltage at both ends at a pre-determined value and protecting the circuit components behind from damage due to transient high-voltage shock. This protector can effectively suppress lightning and ESD, providing 600W of lightning surge protection power per wire, as well as surge voltages and transient over-voltages generated by various causes on the wire. The extremely small inter-pole capacitance ensures high-speed transmission of the RS-485/RS-422 interface.