| 摘要 |
PURPOSE:To absorb noise voltage and energy by providing PNP transistor in semi-conductor integrated circuit and using the substrate as collector while arranging first and second resistors and Zener diode at the outside of circuit. CONSTITUTION:Upon application of positive surge, the power source line 21 for semi-conductor integrated circuit is protected below predetermined voltage level through Zener diode 3 thereby almost all energy is consumed through resistors 1, 2, Zener diode 3 and PNP transistor 8. Upon lapping of negative surge over power source line, current will flow through the path of Zener diode 3 and resistor 1, parasitic diode and resistor 2 between collector and substrate of transistor 7 to absorb almost all energy through the resistors 1, 2 thus to prevent breakdown of semi-conductor integrated circuit. Consequently breakdown due to surge can be prevented sufficiently with small number of parts resulting in reduction of size. |
