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US 6,888,384 B2Granted
Power-on detector, and power-on reset circuit using the same
AssigneeKabushiki Kaisha Toshiba
InventorMasaharu Wada
Life of this patent
Estimating the term…
Abstract
A power-on detector includes a reference potential generation circuit which generates a reference potential, and a comparator which compares the first voltage generated on the basis of the reference potential output from the reference potential generation circuit and the potential of the first potential supply source, and the second voltage generated on the basis of the reference potential and the potential of the second potential supply source different from the potential of the first potential supply source. Power-on is detected when the potential difference between the potentials of the first and second potential supply sources upon power-on becomes larger than the sum of the first and second voltages.
Claims17
A power-on detector comprising:
- a current generation circuit having a first output terminal and a second output terminal and configured to produce a first current and a second current from the first output terminal and the second output terminal, respectively, the first current and the second current having a low degree of temperature dependency and being substantially equal to each other;
- a first load element connected between the first output terminal of the current generation circuit and a first potential supply source;
- a current mirror circuit having a first current path and a second current path, the first current path being connected to the second output terminal of the current generation circuit;
- a second load element connected between the second current path of the current mirror circuit and a second potential supply source;
- and
- a first comparator having a first input terminal connected to the first output terminal of the current generation circuit, and a second input terminal connected to a connection node between the second load element and the current mirror circuit, the first comparator making a comparison between (i) a first voltage obtained by causing the first current output from the first output terminal of the current generation circuit to flow to the first potential supply source by way of the first load element, and (ii) a second voltage obtained by causing a current flowing from the second potential supply circuit to the second current path of the current mirror circuit by way of the second load element,
- wherein power-on is detected when the second voltage becomes higher than the first voltage when a power supply is turned on.
4 more elements
A power-on reset circuit comprising:
- a data holding circuit which holds data;
- a current generation circuit having a first output terminal and a second output terminal and configured to produce a first current and a second current from the first output terminal and the second output terminal, respectively, the first current and the second current having a low degree of temperature dependency and being substantially equal to each other;
- a first load element connected between the first output terminal of the current generation circuit and a first potential supply source;
- a current mirror circuit having a first current path and a second current path, the first current path being connected to the second output terminal of the current generation circuit;
- a second load element connected between the second current path of the current mirror circuit and a second potential supply source;
- a first comparator having a first input terminal connected to the first output terminal of the current generation circuit, and a second input terminal connected to a connection node between the second load element and the current mirror circuit, the first comparator making a comparison between (i) a first voltage obtained by causing the first current output from the first output terminal of the current generation circuit to flow to the first potential supply source by way of the first load element, and (ii) a second voltage obtained by causing a current flowing from the second potential supply circuit to the second current path of the current mirror circuit by way of the second load element;
- and
- a reset circuit which resets the data held by the data holding circuit on the basis of an output signal from the first comparator,
- wherein the reset circuit resets the data held by the data holding circuit when the second voltage becomes higher than the first voltage when a power supply is turned on.
6 more elements
Dependencies are inferred from the claim text.