| 摘要 |
PURPOSE:To obtain a constant current control circuit which is reduced in pattern size sufficiently in case of IC-implementation by providing an analog switch to the gate of an MOS transistor (TR), and controlling the conduction of the TR through the switching of the switch. CONSTITUTION:The drain and gate of the MOSTR11 are connected to each other and a constant current I0 is supplied from a terminal A. The gate of the TR11 is connected to the gate of an MOSTR12 through the analog switch SW13 and the TR12 allows a constant current I'0 to flow to a terminal OUT. The sources of the TRs 11 and 12 are connected to a power source VSS, and the gate of the TR12 is connected to the power source VSS through an SW14. The SW13 is connected to a control input terminal IN and the SW14 is connected to the terminal IN through an inverter 15. When an H-level signal is applied to the terminal IN, the SW13 is closed to flow the current I'0 to the TR12 and the TRs 11 and 12 constitute a current mirror circuit; when the TRs 11 and 12 are of the same size, I0=I'0. When an L-level signal is applied to the terminal IN, the SW13 is opened and the SW14 is closed to turn off the TR12, turning off the constant current circuit. |
