Computer battery pack charge current sensor with gain control
First Claim
1. A current sensor for monitoring discharge currents from a battery while the battery is connected to a system capable of discharging the battery in at least first and second discharge states, the system providing an indication of the first discharge state and an indication of the second discharge state, the current sensor comprising:
- a first sense resistor for coupling in series with the battery during the first discharge state and having a first terminal for providing a first current signal indicating the current in the battery during the first discharge state;
a second sense resistor for coupling in series with the battery during the second discharge state and having a first terminal for providing a second current signal indicating the current in the battery during the second discharge state;
a third resistor having a first terminal for receiving the second current signal and a second terminal for providing a sense signal indicative of the current in the battery during the second discharge state;
a first switch having a series switched path activated by a control terminal for coupling said first resistor and the battery in series when the system indicates the first discharge state and for decoupling said first resistor and the battery when the system indicates the second discharge state; and
a second switch having a series switched path activated by a control terminal, the series switched path of said second switch having a first terminal coupled to the first terminal of said first sense resistor for receiving the first current signal and having a second terminal coupled to the second terminal of said third resistor for providing the sense signal when the system indicates the first discharge state.
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Accused Products
Abstract
A current switch is provided which selects and monitors charge and discharge states of a battery pack of a computer system. The current switch provides a current sense signal which is an indication of the current in the battery pack in order that a charge control circuit can monitor the charge state of the battery pack. The gain of the current sense signal is adjusted, depending on whether the battery pack is in a fast charging, trickle charging, or discharging state when the computer system is in a standby mode. Thus, the current switch provides a sufficient current sense signal for accurate current measurements while dissipating little power for the various battery pack charge states.
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Citations
16 Claims
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1. A current sensor for monitoring discharge currents from a battery while the battery is connected to a system capable of discharging the battery in at least first and second discharge states, the system providing an indication of the first discharge state and an indication of the second discharge state, the current sensor comprising:
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a first sense resistor for coupling in series with the battery during the first discharge state and having a first terminal for providing a first current signal indicating the current in the battery during the first discharge state; a second sense resistor for coupling in series with the battery during the second discharge state and having a first terminal for providing a second current signal indicating the current in the battery during the second discharge state; a third resistor having a first terminal for receiving the second current signal and a second terminal for providing a sense signal indicative of the current in the battery during the second discharge state; a first switch having a series switched path activated by a control terminal for coupling said first resistor and the battery in series when the system indicates the first discharge state and for decoupling said first resistor and the battery when the system indicates the second discharge state; and a second switch having a series switched path activated by a control terminal, the series switched path of said second switch having a first terminal coupled to the first terminal of said first sense resistor for receiving the first current signal and having a second terminal coupled to the second terminal of said third resistor for providing the sense signal when the system indicates the first discharge state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A current sensor for monitoring charge currents in a battery while the battery is connected to a system capable of charging the battery in at least first and second charge states, the system providing an indication of the first charge state and an indication of the second charge state, the current sensor comprising:
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a first sense resistor for coupling in series with the battery during the first charge state and having a first terminal for providing a first current signal indicating the current in the battery during the first charge state; a second sense resistor for coupling in series with the battery during the second charge state and having a first terminal for providing a second current signal indicating the current in the battery during the second charge state; a third resistor having a first terminal for receiving the second current signal and having a second terminal for providing a sense signal indicative of the current in the battery during the second charge state; a first switch having a series switched path activated by a control terminal for coupling said first resistor and the battery in series when the system indicates the first charge state and for decoupling said first resistor and the battery when the system indicates the second charge state; and a second switch having a series switched path activated by a control terminal, the series switched path of said second switch having a first terminal coupled to the first terminal of said first resistor for receiving the first current signal and having a second terminal coupled to the second terminal of said third resistor for providing the sense signal when the system indicates the first charge state. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification