Patent ID: 7990206

Claim:
A negative voltage supply device, comprising: a first negative voltage detector for detecting a level of a negative voltage to output a first detection signal indicating that the level of the negative voltage is less than a first voltage; a second negative voltage detector for detecting a level of the negative voltage to provide a second detection signal indicating that the level of the negative voltage is less than a second voltage which is lower than the first voltage; a third negative voltage detector for detecting a level of the negative voltage to generate a third detection signal indicating that the level of the negative voltage is less than a third voltage varying with temperature; a clamping part for logically combining the first detection signal, the second detection signal, and the third detection signal to output a fourth detection signal causing a level of the negative voltage to be dependent on temperature between the first voltage and the second voltage; and a negative voltage pumping unit for pumping the negative voltage in response to the fourth detection signal, wherein the first and second voltages have a constant voltage level, respectively.