Voltage Generation Circuit

Abstract

A voltage generation circuit supplies an internal power supply voltage to an internal circuit via an output terminal and includes a regulator, a second drive element, and a control circuit The regulator includes a first drive element disposed between an external power supply VDD (first power supply) and an output terminal, and supplies a voltage based on a reference voltage to the output voltage by controlling the first drive element. The second drive element is disposed between the external power supply VDD and the output terminal, and supplies a voltage of the external power supply VDD to the output terminal when activated. When a voltage of the external power supply is a previously set detection voltage value or less, the control circuit activates the first and the second drive element, and when the voltage of the external power supply exceeds the detection voltage value, deactivates the second drive element.

1 - 19 . (canceled) 
     
     
         20 . A voltage generation circuit, comprising:
 an output port;   a regulator including a first transistor disposed between a power supply voltage and the output port, and an amplifier disposed between a gate of the first transistor and a reference voltage;   a second transistor disposed between the power supply voltage and the output port; and   a control circuit that controls the regulator and the second transistor,   wherein, when the power supply voltage is less than or equal to a predetermined voltage, the control circuit activates the second transistor and deactivates the regulator by clamping an output voltage of the amplifier, and   wherein, when the power supply voltage exceeds the predetermined voltage, the control circuit deactivates the second transistor.   
     
     
         21 . The voltage generation circuit according to  claim 20 , further comprising:
 a third transistor disposed between the power supply voltage and an output of the amplifier,   wherein, when the power supply voltage is less than or equal to the predetermined voltage, the control circuit activates the third transistor.   
     
     
         22 . The voltage generation circuit according to  claim 20 , further comprising:
 a detection circuit that detects whether or not the power supply voltage is less than or equal to the predetermined voltage.   
     
     
         23 . The voltage generation circuit according to  claim 20 , wherein an output voltage of the regulator is a reduced voltage from the power supply voltage. 
     
     
         24 . The voltage generation circuit according to  claim 21 , wherein the first transistor is a first conductivity type transistor, and the second and third transistors are second conductivity type transistors.