The SP721 is an array of SCR/Diode bipolar structures for ESD and over-voltage protection to sensitive input circuits. The SP721 has 2 protection SCR/Diode device structures per input. There are a total of 6 available inputs that can be used to protect up to 6 external signal or bus lines. Over-voltage protection is from the IN (Pins 1 - 3 and Pins 5 - 7) to V+ or V-.
The SCR structures are designed for fast triggering at a threshold of one +VBE diode threshold above V+ (Pin 8) or a -VBE diode threshold below V- (Pin 4). 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.

Features
• ESD Interface Capability for HBM Standards
   - MIL STD 3015.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15kV
   - IEC 61000-4-2, Direct Discharge,
   - Single Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4kV (Level 2)
   - Two Inputs in Parallel . . . . . . . . . . . . . . . . . . . . . . . . . . 8kV (Level 4)
   - IEC 61000-4-2, Air Discharge . . . . . . . . . . . . . . . . . . 15kV (Level 4)
• High Peak Current Capability
   - IEC 61000-4-5 (8/20µs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±3A
   - Single Pulse, 100µs Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . ±2A
   - Single Pulse, 4µs Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . . . ±5A
• Designed to Provide Over-Voltage Protection
   - Single-Ended Voltage Range to . . . . . . . . . . . . . . . . . . . . . . . . +30V
   - Differential Voltage Range to. . . . . . . . . . . . . . . . . . . . . . . . . . . ±15V
• Fast Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2ns Rise Time
• Low Input Leakages . . . . . . . . . . . . . . . . . . . . . . . . 1nA at 25°C Typical
• Low Input Capacitance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3pF Typical
• An Array of 6 SCR/Diode Pairs
• Operating Temperature Range . . . . . . . . . . . . . . . . . . . . -40°C to 105°C

Applications
• Microprocessor/Logic Input Protection
• Data Bus Protection
• Analog Device Input Protection
• Voltage Clamp