US 6,472,912 B1 · Device for power supply detection and power on reset

Abstract

A circuit for power supply detection and power on reset. The circuit comprises two separate component groups for producing separate currents which vary in response to the level of a voltage source. For example, each may have a non-linear DC relationship between the power supply and a current of the respective component groups. Furthermore, the DC voltage to current relationship of two groups is different. The circuit has an output with two modes. The two component groups are operable to force the output into one mode when the voltage source is above a threshold and a second mode when the voltage source is below the threshold. Therefore, the circuit is operable to detect when the supply voltage has dropped below a threshold and to also serve as a power on reset. However, the circuit does not rely on the threshold voltage of a transistor to trigger the output.

Claims11

Dependent claims

A circuit for monitoring the level of a voltage comprising:

a first circuit for producing a current which varies in response to the level of said voltage, said first circuit comprising:
a first resistor coupled to said voltage;
a first transistor coupled to said resistor;
a second transistor with its gate coupled to the gate of said first transistor;
a second circuit coupled to said first circuit and for producing a current which varies in response to the level of said voltage, said first and second circuits having different responses to said voltage, said second circuit comprising:
a second resistor coupled to said voltage;
a third transistor coupled to said resistor;
a fourth transistor with its gate coupled to the gate of said third transistor, wherein said first, second, third, and fourth transistors have different widths;
said circuit having an output taken from said second transistor operable to go between two modes in response to the level of said voltage.

6 more elements

Dependencies are inferred from the claim text.

Device for power supply detection and power on reset

Life of this patent

Device for power supply detection and power on reset

Life of this patent

Abstract

Claims11