Battery charger circuit and control schemes
First Claim
1. A battery charger circuit having first and second terminals coupled to respective terminals of a battery, the battery charger circuit comprising:
- a control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element comprising a low-power detector circuit coupled to the first one of the inputs of said control element, said low-power detector circuit configured to sense and detect changes in a battery voltage signal, said control element configured to receive a reference voltage signal corresponding to a predetermined voltage target level of the sensed battery voltage signal at a second one of the inputs and generate a control element current signal at an output thereof in response to the sensed battery voltage signal and the reference voltage signal, said control element having an output current response characteristic which varies with respect to the sensed battery voltage signal such that said control element implements a saturating function that causes charging current provided to the first and second terminals of the battery charger circuit to automatically transition between one of;
a constant current operating mode and a constant voltage operating mode;
or a constant voltage operating mode to a constant current operating mode; and
an end-of-charge detection circuit having at least first and second inputs with a first one of the inputs adapted to couple to the control element output, said end-of-charge detection circuit configured to receive the control element current signal at the first one of the inputs and a reference current signal at a second one of the inputs and in response thereto said end-of-charge detection circuit compares the control element current signal with the reference current signal to detect end-of-charge at the first and second terminals of the battery charger circuit, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode.
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Accused Products
Abstract
Described is a battery charger circuit for charging a battery. The battery charger circuit comprises a control element having a first input configured to receive an input from a reference source, a second input configured to receive an input from the battery and an output, said control element having an output current response characteristic which varies with respect to the battery input such that said control element implements a saturating function that causes the charging current of the battery to automatically transition between a constant current operating mode and a constant voltage operating mode or a constant voltage operating mode to a constant current operating mode.
17 Citations
28 Claims
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1. A battery charger circuit having first and second terminals coupled to respective terminals of a battery, the battery charger circuit comprising:
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a control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element comprising a low-power detector circuit coupled to the first one of the inputs of said control element, said low-power detector circuit configured to sense and detect changes in a battery voltage signal, said control element configured to receive a reference voltage signal corresponding to a predetermined voltage target level of the sensed battery voltage signal at a second one of the inputs and generate a control element current signal at an output thereof in response to the sensed battery voltage signal and the reference voltage signal, said control element having an output current response characteristic which varies with respect to the sensed battery voltage signal such that said control element implements a saturating function that causes charging current provided to the first and second terminals of the battery charger circuit to automatically transition between one of;
a constant current operating mode and a constant voltage operating mode;
or a constant voltage operating mode to a constant current operating mode; andan end-of-charge detection circuit having at least first and second inputs with a first one of the inputs adapted to couple to the control element output, said end-of-charge detection circuit configured to receive the control element current signal at the first one of the inputs and a reference current signal at a second one of the inputs and in response thereto said end-of-charge detection circuit compares the control element current signal with the reference current signal to detect end-of-charge at the first and second terminals of the battery charger circuit, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A power management integrated circuit (IC) having first and second terminals coupled to respective terminals of one or more rechargeable cells, the power management IC comprising:
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a control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element comprising a low-power detector circuit coupled to the first one of the inputs of said control element, said low-power detector circuit configured to sense and detect changes in a battery voltage signal, said control element configured to receive a reference voltage signal corresponding to a predetermined voltage target level of the sensed batter voltage signal at a second one of the inputs and generate a control element current signal at an output thereof in response to the sensed battery voltage signal and the reference voltage signal, said control element having an output current response characteristic which varies with respect to the sensed battery voltage signal such that said control element provides a continuous charging current and automatically transitions from one of;
a constant current operating mode to a constant voltage operating mode;
or a constant voltage operating mode to a constant current operating mode;an end-of-charge detection circuit having at least first and second inputs with a first one of the inputs adapted to couple to the control element output, said end-of-charge detection circuit configured to receive the control element current signal at the first one of the inputs and a reference current signal at a second one of the inputs and in response thereto said end-of-charge detection circuit compares the control element current signal with the reference current signal to detect end-of-charge at the first and second terminals of the power management IC; and a gain circuit having a first input coupled to the control element output, a second input coupled to the end-of-charge detection circuit output and having an output configured to couple to the first and second terminals of the power management IC, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode. - View Dependent Claims (20, 21, 22, 23, 24)
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25. A method for charging a battery with a battery charger circuit having first and second terminals coupled to respective terminals of the battery, the method comprising:
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sensing and detecting changes in a battery voltage signal at a control element comprised in the battery charger circuit, said control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit; comparing the sensed battery voltage signal with a reference voltage signal corresponding to a predetermined voltage target level of the sensed battery voltage signal to determine a charging current; in response to the comparing, generating a control element current signal and providing a continuous charging current to the first and second terminals of the battery charger circuit and automatically transitioning between one of;
a constant current operating mode and a constant voltage operating mode;
or a constant voltage operating mode and a constant current operating mode; andcomparing the control element current signal with a reference current signal to detect end-of-charge at the first and second terminals of the battery charger circuit, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode.
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26. A battery charger circuit having first and second terminals coupled to respective terminals of a battery, the battery charger circuit comprising:
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a control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element comprising a low-power detector circuit coupled to the first one of the inputs of said control element, said low-power detector circuit configured to sense and detect changes in a battery voltage signal, said control element configured to receive a reference voltage signal corresponding to a predetermined voltage target level of the sensed battery voltage signal at a second one of the inputs and generate a control element current signal at an output thereof in response to the sensed battery voltage signal and the reference voltage signal, said control element having an output current response characteristic which varies with respect to the sensed battery voltage signal such that said control element continuously provides a charging current that transitions the first and second terminals of the battery charger circuit from one of;
a constant current operating mode to a constant voltage operating mode;
or a constant voltage operating mode to a constant current operating mode; andan end-of-charge detection circuit having at least first and second inputs with a first one of the inputs adapted to couple to the control element output, said end-of-charge detection circuit configured to receive the control element current signal at the first one of the inputs and a reference current signal at a second one of the inputs and in response thereto said end-of-charge detection circuit compares the control element current signal with the reference current signal to detect end-of-charge at the first and second terminals of the battery charger circuit, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode.
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27. A battery charger circuit having first and second terminals coupled to respective terminals of a battery, the battery charger circuit comprising:
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a control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element comprising a low-Dower detector circuit coupled to the first one of the inputs of said control element, said low-power detector circuit configured to sense and detect changes in a battery voltage signal, said control element configured to receive a reference voltage signal corresponding to a predetermined voltage target level of the sensed batten voltage signal at a second one of the inputs and generates a control element current signal at an output thereof in response to the sensed battery voltage signal and the reference voltage signal, said control element having an output current response characteristic corresponding to a saturating function that causes the charging current provided to the first and second terminals of the battery charger circuit to automatically transition between a constant current operating mode and a constant voltage operating mode or a constant voltage operating mode to a constant current operating mode which varies with respect to the sensed battery voltage signal; and an end-of-charge detection circuit having at least first and second inputs with a first one of the inputs adapted to couple to the control element output, said end-of-charge detection circuit configured to receive the control element current signal at the first one of the inputs and a reference current signal at a second one of the inputs and in response thereto said end-of-charge detection circuit compares the control element current signal with the reference current signal to detect end-of-charge at the first and second terminals of the battery charger circuit, wherein said control element is implemented as an operational transconductance amplifier (OTA) and the output current response characteristic of said control element has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode.
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28. A battery charger circuit having first and second terminals coupled to respective terminals of a battery, the battery charger circuit comprising:
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a control element provided as a operational transconductance amplifier (OTA), said control element having at least first and second inputs with a first one of the inputs coupled to a corresponding terminal of the battery charger circuit, said control element configured to receive a battery voltage signal at the first one of the inputs and a reference voltage signal corresponding to a predetermined voltage target level of the battery voltage signal at a second one of the inputs and in response thereto said control element generates a control element current signal at an output thereof, said control element having an output current response characteristic which varies with respect to the battery voltage signal provided thereto such that said control element implements a saturating function that causes charging current provided to the first and second terminals of the battery charger circuit to automatically transition between one of;
a constant current operating mode and a constant voltage operating mode;
or a constant voltage operating mode to a constant current operating mode,wherein the output current response characteristic of said OTA has a shape corresponding to the shape of a hyperbolic tangent function, the output response characteristic of said control element utilized to transition the charging current between the constant current operating mode and the constant voltage operating mode.
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Specification