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US 6,150,805 AGranted
Self-canceling start-up pulse generator
AssigneeFairchild Semiconductor Corporation
InventorA. Karl Rapp
Life of this patent
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Abstract
A method and circuits for generating a start-up signal to force a bistable reference circuit into a conducting state. The start-up signal ensures that the reference circuit operates to provide a desired output signal when power is applied. The start-up signal is self-generated and self-canceled, rather than relying on an externally supplied pulse, and is input to the reference circuit via a hysteresis circuit (e.g., Schmitt inverter).
Claims10
A start-up pulse generator comprising:
- a bistable reference circuit having an input terminal and an output terminal, and which outputs at said output terminal a first voltage level in a first steady state and a second voltage level in a second steady state;
- a monitor having an input terminal coupled to said reference circuit output terminal, and which outputs at an output terminal a first output signal upon receipt of said first voltage level and a second output signal upon receipt of said second voltage level;
- a hysteresis circuit having an input terminal coupled to said monitor output terminal, and an output terminal;
- and
- a start-up signal generator having an input terminal coupled to said hysteresis circuit output terminal, and an output terminal coupled to said reference circuit input terminal, and which provides a start-up signal to said reference circuit upon receipt of said first output signal.
2 more elements
A method of generating a self-canceling start-up pulse comprising:
- monitoring a signal level in a bistable reference circuit;
- providing via a hysteresis circuit a current to said reference circuit when said signal level is within a first predetermined range;
- using said current to force said bistable reference circuit into a first steady state;
- and
- removing said current when said signal level is within a second predetermined range.
2 more elements
Dependencies are inferred from the claim text.