| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to configure a constant-current constant-voltage circuit using elements having a lower withstand voltage than a power supply voltage and to improve input stability.SOLUTION: If a power supply voltage Vdd rises, a voltage of an intermediate node 14 and a gate potential of transistors M3 and M4 are to rise. A gate voltage of a transistor M5 rises accordingly, so that a drain current of the transistor M5 increases. As a result, a current flowing across a resistance R1 increases to suppress a voltage rise of the intermediate node 14. This feedback action allows for generation of a constant voltage Vb on the intermediate node 14. A constant current Ib flows across a serial circuit of a resistance R2 and the transistors M3 and M2 since a voltage equal to a voltage of a Zener diode D1 is applied to the resistance R2. |
