POWER SUPPLY CIRCUIT AND BATTERY DEVICE
First Claim
1. A power supply circuit, that steps down an input voltage and outputs it, comprising:
- a charge pump circuit for outputting an intermediate voltage in which the input voltage has been stepped down;
a voltage regulator circuit including an active element circuit being connected between an output terminal of the intermediate voltage of the charge pump circuit and an output terminal of the power supply voltage and a feedback control circuit for feedback-controlling the active element circuit so that the power supply voltage approaches a predetermined voltage;
a voltage detecting circuit for detecting said input voltage or the voltage being applied to the active element circuit; and
a control circuit that switches the operating mode of the charge pump circuit so that the step-down ratio is increased if the voltage being detected in the voltage detecting circuit exceeds a predetermined voltage threshold.
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Accused Products
Abstract
A power supply circuit with low noise and low power consumption and a battery device using the power supply circuit. If a voltage VDD is higher than a prescribed voltage, a charge pump circuit 140A is operated in “½ mode” (a step-down ratio of “2”), steps down the voltage VDD, and outputs an intermediate voltage VCPO. Since the voltage VDD is stepped down, the intermediate voltage VCPO being input into a first LDO 135 is about half the case where no step-down is carried out, and the power being consumed in a MOS transistor Q11 (FIG. 3) of the first LDO 135 is greatly reduced. Therefore, the increase in power consumption of the first LDO 135 due to a voltage increase in the voltage VDD can be suppressed. Also, since the heat sink of the first LDO 135 can be reduced in size or omitted by the suppression of power consumption, the size and weight of the device can be reduced.
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Citations
7 Claims
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1. A power supply circuit, that steps down an input voltage and outputs it, comprising:
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a charge pump circuit for outputting an intermediate voltage in which the input voltage has been stepped down;
a voltage regulator circuit including an active element circuit being connected between an output terminal of the intermediate voltage of the charge pump circuit and an output terminal of the power supply voltage and a feedback control circuit for feedback-controlling the active element circuit so that the power supply voltage approaches a predetermined voltage;
a voltage detecting circuit for detecting said input voltage or the voltage being applied to the active element circuit; and
a control circuit that switches the operating mode of the charge pump circuit so that the step-down ratio is increased if the voltage being detected in the voltage detecting circuit exceeds a predetermined voltage threshold. - View Dependent Claims (2, 3, 4, 5, 7)
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6. In a battery device, equipped with a battery, a switching circuit installed in a power supply path comprising:
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a battery protecting circuit for controlling on/off of the switching circuit in accordance with a control signal being input;
a power supply circuit that steps down the voltage of the battery and supplies the stepped-down voltage as a power supply voltage to the battery protecting circuit, the power supply circuit having a charge pump circuit for outputting an intermediate voltage in which the voltage of the battery has been stepped down;
a voltage regulator circuit having an active element circuit connected between an output terminal of the intermediate voltage of the charge pump circuit and an output terminal of the power supply voltage and a feedback control circuit for feedback-controlling the active element circuit so that the power supply voltage approaches a predetermined voltage;
a voltage detecting circuit for detecting the voltage of the battery or the voltage being applied to the active element circuit; and
a control circuit that switches the operating mode of the charge pump circuit so that the step-down ratio is increased if the voltage being detected in the a voltage detecting circuit exceeds a predetermined voltage threshold.
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Specification