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Charging apparatus that can recharge different types of batteries without overcharging them

a charging apparatus and battery technology, applied in the direction of electric vehicles, electric generators, transportation and packaging, etc., can solve the problems of increasing circuit area and/or current consumption, increasing current consumption, and affecting the operation of the charging apparatus, so as to prevent overcharging and increase the circuit area and current consumption.

Active Publication Date: 2014-06-24
LAPIS SEMICON CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]It is an object of the present invention to provide a charging apparatus which is capable of preventing overcharging by coping with a plurality of cell voltages without increasing a circuit area and current consumption.
[0008]The charging apparatus of the present invention can prevent overcharging by coping with a plurality of cell voltages without increasing a circuit area and current consumption.

Problems solved by technology

To prepare a circuitry capable of coping with a plurality of cell voltages may encounter an increase in circuit area and / or an increase in current consumption.
This results in an increase in circuit area.
This results in an increase in current consumption.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0016]Referring to FIG. 1, a charging apparatus 1 of a first embodiment is equipped with a solar cell 2 and a secondary battery 3. The solar cell 2 is a charging current supply source. The charging apparatus 1 prevents back flow of a charging current supplied from the solar cell 2 to an input terminal 91 and supplies the charging current to the secondary battery 3. The secondary battery 3 is connected to an output terminal 92. The charging apparatus 1 also has a function of preventing overcharging of the secondary battery 3. The charging apparatus 1 includes a back flow prevention unit 10, a step-down unit 20, a discharging unit 30, and a comparison unit 40.

[0017]The back flow prevention unit 10 is a circuit that prevents back flow of a current from the secondary battery 3 to the solar cell 2. In this specification, the solar cell 2 side of the back flow prevention unit 10 will be referred to as an upper stream, and the secondary battery side of the back flow prevention unit 10 will...

modification to first embodiment

[0046]FIG. 3 is a block diagram showing the configuration of a charging apparatus 1 according to a modified embodiment of the first embodiment. A description will be mostly given of those parts and elements in this modification which are different from those in the first embodiment. Similar reference numerals and symbols are used to designate similar parts and elements in the first embodiment and its modification. The charging apparatus 1 of the modification prevents overcharging of a secondary battery (first supply destination) 3 of a relatively large capacity and another secondary battery (second supply destination) 4 of a relatively small capacity and performs a charging process while switching a charging current supply destination between the secondary battery 3 and the secondary battery 4. The charging apparatus 1 of FIG. 3 includes a switching unit 79. The configuration of the switching unit 79 will hereinafter be described.

[0047]A VDD voltage detector 80 has an input connecte...

second embodiment

[0070]Referring to FIG. 5, a charging apparatus 1 of a second embodiment is illustrated together with a solar cell 2 and a secondary battery 3. A description will be mostly given of those parts and elements in the second embodiment which are different from those in the first embodiment. The charging apparatus 1 of the second embodiment does not include the select signal input terminal 49 and inverter 50 shown in FIG. 1 and includes NMOSs 51 and 52 and select signal input terminals 53 to 55 in the comparison unit 40. Similar reference numerals and symbols are used in the first and second embodiments when designating similar parts and elements.

[0071]The gate of the NMOS 46 is connected to the select signal input terminal 53. The gate of the NMOS 48 is connected to the select signal input terminal 54. Other connections of the NMOSs 45 to 48 are the same as those in the first embodiment.

[0072]The NMOS 51 has a source connected to the drain of the NMOS 52, a gate connected to the output ...

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Abstract

A charging device can prevent overcharging by coping with a plurality of cell voltages without increasing a circuit area and current consumption. The charging device selects one of at least two judgment voltages in response to a select signal determined depending on a chargeable voltage of a secondary battery. The charging device compares a comparison voltage based on a voltage of a lower stream of a back flow prevention unit with the selected judgment voltage to detect a fully charged state of the secondary battery. The charging device interrupts supply of charging current to the back flow prevention unit upon detecting the fully charged state.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a charging apparatus that can prevent overcharging of a secondary battery.[0003]2. Description of the Related Art[0004]A so-called secondary battery (also referred to as a storage battery, accumulator or rechargeable battery) that is repeatedly usable as a battery by being charged again and again is known in the art. When charging the secondary battery, measures to deal with overcharging of the secondary battery are taken to prevent breakdown or damage of the secondary battery. For example, Japanese Patent Application Publication (Kokai) No. 9-261861 discloses an apparatus for such purpose. When a voltage across a secondary battery becomes higher than or equal to a predetermined value, an N-channel power metal oxide semiconductor field effect transistor (MOSFET) connected in parallel to a solar cell is turned on to interrupt charging current from the solar cell to the battery, thereby pr...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01M10/46
Inventor UTSUNO, KIKUO
Owner LAPIS SEMICON CO LTD