The SP720 is an array of SCR/Diode bipolar structures for ESD and over-voltage protection to sensitive input circuits. The SP720 has 2 protection SCR/Diode device structures per input. A total of 14 available inputs can be used to protect up to 14 external signal or bus lines. Over-voltage protection is from the IN (pins 1-7 and 9-15) to V+ or V-.

The SCR structures are designed for fast triggering at a threshold of one +VBE diode threshold above V+ (Pin 16) or a -VBE diode threshold below V- (Pin 8). From an IN input, a clamp to V+ is activated if a transient pulse causes the input to be increased to a voltage level greater than one VBE above V+. A similar clamp to V- is activated if a negative pulse, one VBE less than V-, is applied to an IN input.