| 摘要 |
PURPOSE: To obtain sufficient current driving capability while securing operation in the safe operation area of NPN by providing a resistance between a low- voltage power source terminal and a low-voltage power source wire to a buffer circuit. CONSTITUTION: The base currents of NPN transistor's(TR) SN (SN1 SNn ) are supplied from the low-voltage power source terminal VCC through P-MOSFET MPs (MP1-MPn) in the buffer circuit, and there is a difference in the total of the base currents of elements SN which is an integral multiple of the number of channels of a driving circuit between load driving and load discharging. Therefore, when all the elements SN are on, i.e., in the safe operation area, the voltages between the gates and sources, and drains and sources of the elements MP supplied with the base currents drop because of the voltage drop across the resistance R provided between the terminal VCC and buffer circuit B, so the outputs of the elements MP, i.e., the base currents of the elements SN decrease to suppress sink currents of the elements SN. Therefore, the safe operation area can be protected.
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