Because an interface IC's built-in protection is no match for the common electrostatic discharge (ESD) from a person's touch, interface ports need external protection from diodes such as those in the NEC Electronics' NSAD and NNCD Series.

NEC NSAD Surge Absorber Diode Features:

• Protection for data lines at speeds up to 500 Mbps (USB 2.0, IEEE 1394, 100B interface, etc.)
• Unique bidirectional protection with breakdown voltages in both positive and negative directions (for signal swings such as –5.3V ~ +8V @25°C). No VCC connection is needed.
• Reduced cost and space with two or four bidirectional diodes per package. Competitors must use four or eight diodes in larger packages to protect the same number of data lines and connect to VCC.
• Ensure protection with +/-14 kV specs – far exceeding the 8 kV requirements of IEC 61000-4-2 Level 4

NEC NNCD Noise Clipping Diode Features:

• Protection against internal and external surges-waveform clipper, power supply, surge absorber, etc.
• Protection for data lines at speeds up to 20 Mbps
• Both High-ESD Series and Low-Capacitance Series