| 摘要 |
PURPOSE: A protective circuit for an electrostatic discharge(ESD) is to improve the tolerance of the ESD by providing a PNP bipolar transistor and an NPN bipolar transistor with an option transistor. CONSTITUTION: The protective circuit comprises a pad(11), a main chip(12), and a resistor(R1) connected between the pad and the main chip. The first PNP bipolar transistor(31,32) is connected between the pad and the resistor, and is connected to Vcc or Vss, respectively. The second NPN bipolar transistor(33) is connected between the first NPN bipolar transistor and the resistor, and is connected to the Vss. A diode NMOS(n-channel metal oxide silicon) transistor(15) is connected between the resistor and the main chip, and is connected to the Vss. A collector of the second NPN bipolar transistor is connected to an output(N1) of the pad, and a base and emitter are connected to the Vss.
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