Zero current detector
AssigneeTexas Instruments Incorporated
InventorsSrinivas Venkata Veeramreddi, Subhash Sahni
Life of this patent
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Abstract
A switch-mode power supply and a zero current detector for use therein. A zero current detector includes an input stage and an output stage. The output stage is coupled to the input stage. The output stage includes a detector output terminal, a first transistor, and a second transistor. The first transistor includes an input terminal and a control terminal. The input terminal is coupled to the detector output terminal. The control terminal is coupled to the input stage. The second transistor includes an input terminal, a control terminal, and an output terminal. The input terminal is coupled to the control terminal of the first transistor. The control terminal is coupled to the input terminal of the second transistor. The output terminal is coupled to ground.
Claims19
A switch-mode power supply, comprising:
- an inductor comprising a terminal;
- a high-side power transistor comprising a first terminal and a second terminal, the first terminal coupled to the terminal of the inductor;
- a low-side power transistor comprising a first terminal and a second terminal, the first terminal coupled to the terminal of the inductor;
- a controller comprising an input terminal, a first output terminal, and a second output terminal, the first output terminal of the controller coupled to the second terminal of the high-side power transistor, and the second output terminal of the controller coupled to the second terminal of the low-side power transistor;
- a zero current detector comprising an output terminal and an input terminal, the output terminal of the zero current detector coupled to the input terminal of the controller, the input terminal of the zero current detector coupled to the terminal of the inductor, and the zero current detector comprising:
- a detection transistor comprising a first terminal and a second terminal, the first terminal coupled to the input terminal of the zero current detector;
- a first transistor comprising:
- a first terminal coupled to the output terminal of the zero current detector;
- and
- a second terminal;
- and
- a pre-charge circuit comprising:
- a terminal coupled to the second terminal of the detection transistor and to the second terminal of the first transistor;
- a second transistor comprising a first terminal and a second terminal;
- and
- a switch coupled between the second terminal of the first transistor and the terminal of the pre-charge circuit.
A circuit, comprising:
- a controller comprising an input terminal and an output terminal;
- and
- a zero current detector coupled to the controller, the zero current detector comprising:
- an input stage comprising an input terminal and an output terminal, the input terminal coupled to the output terminal of the controller;
- and
- an output stage comprising:
- a detector output terminal coupled to the input terminal of the controller;
- a first transistor, comprising:
- an input terminal coupled to the detector output terminal;
- and
- a control terminal coupled to the output terminal of the input stage;
- a second transistor comprising:
- an input terminal coupled to the control terminal of the first transistor;
- a control terminal coupled to the input terminal of the second transistor;
- and
- an output terminal coupled to a ground terminal;
- and
- a resistor comprising:
- a first terminal coupled to the control terminal of the first transistor;
- and
- a second terminal coupled to the input terminal of the second transistor.
A zero current detector, comprising:
- an output terminal;
- an input terminal;
- a first negative (N) channel metal oxide semiconductor field effect transistor (MOSFET) comprising a gate terminal, the first N channel MOSFET configured to pull down the output terminal;
- a second N channel MOSFET comprising a drain terminal, the second N channel MOSFET configured to pre-charge the gate terminal of the first N channel MOSFET to a voltage within 90 to 110 millivolts of a threshold voltage of the first N channel MOSFET;
- and
- a switch configured to switchably connect the drain terminal of the second N channel MOSFET to the gate terminal of the first N channel MOSFET to pre-charge the gate terminal prior to receiving an inductor discharge voltage signal at the input terminal.
Dependencies are inferred from the claim text.