TRANSISTOR OUTPUT CIRCUIT, SEMICONDUCTOR DEVICE INCLUDING TRANSISTOR OUTPUT CIRCUIT, AND SWITCHING POWER SUPPLY PROVIDED THE TRANSISTOR OUTPUT CIRCUIT

摘要

PROBLEM TO BE SOLVED: To reduce through current of the transistor output circuit remarkably, to raise/lower an output signal up (down) to power source potential (upper limit value) and ground potential (lower limit value), and to smoothly change the output signal at a part in the vicinity of the power source potential and the ground potential. SOLUTION: A main driver obtained by connecting an NPN and a PNP in series is driven by the output of a predriver having a first CMOS circuit driven by an input signal. In addition, an assist circuit having a second CMOS circuit driven by the input signal and a current restriction resistor is provided, and the output of the main driver is assisted by the output of the assist circuit. Thus, electromagnetic noise (EMI) is made small and a switching output with sufficient amplitude is supplied. COPYRIGHT: (C)2004,JPO