TVS Silicon Protection Arrays (SPA) Littelfuse TVS Diode Arrays SPA™ (Silicon Protection Arrays) are designed to protect electronics from very fast and damaging voltage transients, such as lightning and electrostatic discharge (ESD). These diodes offer an ideal protection solution for I/O interfaces and digital and analog signal lines in computer and consumer portable electronics. Littelfuse TVS SPA diodes offer a broader application use and improved impulse protection performance over conventional diodes.