Patent ID: 7570090

Claim:
A power-on reset circuit comprising: a first transistor having an emitter, a base, and a collector coupled to a first voltage source; a second transistor having an emitter coupled to the base of the first transistor, and a base and collector coupled to the first voltage source; a third transistor having an emitter, a base coupled to the base of the first transistor, and a collector coupled to the first voltage source; a first resistor coupled between a second voltage source and an internal node; a second resistor coupled between the second voltage source and the emitter of the first transistor; a third resistor coupled between the internal node and the emitter of the third transistor; and a comparator having a first input coupled to the internal node and a second input coupled to the emitter of the first transistor for generating a power-on reset signal in response to a voltage at the first input being greater than a voltage at the second input, wherein the second transistor is in the current path of the bases of the first and third transistors.