| 摘要 |
PURPOSE:To facilitate the measurement of a resistance value, by providing a power source monitoring circuit at an input of an output control transistor. CONSTITUTION:Diodes 1-3 will not conduct unless about 2.1V or more of forward voltage is applied to between a VCC terminal and the ground and a ground potential is applied to an input 6 of a CMOS transistor (Tr). With such an arrangement, a PMOSTrQ5 is turned ON while an NMOSTrQ6 OFF and a power source voltage is applied to a gate electrode of high impedance control TrQ4 and Q3 to turn them ON while output TrQ1 and Q2 are turned OFF with gate electrode lines 8 and 9 thereof TrQ1 and Q2 at the ground potential to produce a high impedance output at an output terminal 10. Then, when 5V is applied between the VCC and the ground, the diodes 1-3 conduct and with the application of a high level voltage to the input 6, the TrQ5 and Q6 are turned ON and OFF respectively and the gate electrodes of the TrQ3 and Q4 are turned OFF, which will apply a logic level of a normal operation circuit to the lines 8 and 9 to be outputted at terminal 10.
|
