| 摘要 |
PROBLEM TO BE SOLVED: To obtain a plurality of reference voltages by a small number of pins in a semiconductor integrated circuit when power supply voltages are supplied to a circuit whose power supply is 1.5 V, a circuit whose supply voltage is 3.0 V, etc. SOLUTION: A first reference voltage is inputted into a positive input end of an operational amplifier 10, then an output transistor 14 is driven by an output of the operational amplifier 10. The first reference voltage is outputted from a first output pin 18 which is connected to an output end of the output transistor 14, then converted into a first external reference voltage by an external transistor 20 and an external resistor 22. The first external reference voltage is inputted from a first input pin, then negative feedback is made to the operational amplifier 10. A constant current source 52 is connected to the output end of the output transistor 14 via a resistor 50, then a connection point between the constant current source 52 and the resistor 50 is connected to a positive input end of an operational amplifier 30. An output transistor 34 is driven by an output of the operational amplifier 30, then a voltage which is subjected to voltage conversion of an output of the output transistor is outputted from a second output pin 32, and the negative feedback is made to the operational amplifier 30. An external transistor 40 is driven by the output of the second output pin, then its output is made a second external reference voltage by subjecting the output to voltage conversion by a resistor 42. COPYRIGHT: (C)2008,JPO&INPIT
|
