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US 10,651,665 B2Granted
Current sense apparatus for battery charger systems
AssigneeActive-Semi (BVI), Inc.
InventorJames Allen Kohout
Life of this patent
Estimating the term…
Abstract
A current sense method comprises generating a voltage across a first current mirror of a current sense apparatus, the voltage being proportional to a current flowing through the current sense apparatus when the current is greater than a predetermined current value and applying a minimum drain-to-source voltage limiter to the first current mirror of the current sense apparatus when the current is less than the predetermined current value, wherein, as a result of applying the minimum drain-to-source voltage limiter to the first current mirror, the voltage across the first current mirror is clamped to a predetermined voltage value.
Claims20
A method comprising:
- in a current sense mode, applying a minimum drain-to-source voltage limiter to a first current mirror of a current sense apparatus, wherein, as a result of applying the minimum drain-to-source voltage limiter to the first current mirror, a voltage across the first current mirror is clamped to a predetermined value;
- and
- in a power saving mode, disabling the minimum drain-to-source voltage limiter;
- wherein the current sense apparatus comprises:
- the first current mirror comprising a first switch coupled between a power source and a load, and a second switch comprising a gate connected to a gate of the first switch;
- a first operational amplifier having a first input connected to the first switch and a second input connected to the second switch;
- and
- a second operational amplifier having an output connected to the gate of the first switch, a first input coupled to a first drain/source terminal of the first switch and a second input coupled to a second drain/source terminal of the first switch.
5 more elements
A method comprising:
- generating a voltage across a first current mirror of a current sense apparatus, the voltage being proportional to a current flowing through the current sense apparatus when the current is greater than a predetermined current value;
- and
- applying a minimum drain-to-source voltage limiter to the first current mirror of the current sense apparatus when the current is less than the predetermined current value, wherein, as a result of applying the minimum drain-to-source voltage limiter to the first current mirror, the voltage across the first current mirror is clamped to a predetermined voltage value;
- wherein the current sense apparatus comprises:
- the first current mirror comprising a first switch and a second switch, wherein a gate of the first switch is connected to a gate of the second switch;
- a first operational amplifier having a first input connected to the first switch and a second input connected to the second switch;
- and
- a second operational amplifier having an output connected to the gate of the first switch, a non-inverting input connected to a first drain/source terminal of the first switch and an inverting input connected to a second drain/source terminal of the first switch.
5 more elements
A method comprising:
- passing a current from a power source to a load through a first switch;
- mirroring in a second switch the current passing through the first switch, wherein the second switch comprises a gate connected to a gate of the first switch and a first terminal connected to a first terminal of the first switch;
- driving a voltage at a second terminal of the first switch equal to a voltage at a second terminal of the second switch through a first operational amplifier;
- maintaining a minimum voltage across the first switch through a second operational amplifier having an output connected to the gate of the first switch, a first input coupled to the first terminal of the first switch and a second input coupled to the second terminal of the first switch;
- enabling a reference voltage source connected to one input of the second operational amplifier so that a voltage across the first switch is approximately equal to an output voltage of the reference voltage source during a current sense operation;
- and
- disabling the reference voltage source so that the voltage across the first switch is equal to the current flowing through the first switch times an on-resistance value of the first switch during a power saving operation.
4 more elements
Dependencies are inferred from the claim text.