The disclosure generally relates to charging control technologies and, particularly to a method for controlling a charging current.
A charging device for portable electronic device is generally provided with electrical power (i.e., is provided with an input voltage) through an adaptor or a universal serial bus (USB) power source, so as to provide a charging current for charging the electronic device. It is known that the USB power source generally has an output current limit, for example 100 mA or 500 mA. If the charging current is higher than the USB power source ability, the input voltage is crashed down. Under such an over-charging current situation, a conventional charging device will be turned off because of input under-voltage protection. Once the charging current is less than the current limit, the input voltage retrieves back to its normal/regular value and the charging process resumes. The above-described abnormal situation obviously affects the whole charging operation and terminates the charging process, resulting in a lower charging efficiency.
Therefore, how to avoid the unexpected termination of charging process caused by the over-charging current in the prior art so as to improve the charging efficiency is an urgent topic needed to be solved.
Accordingly, the disclosure is directed to a method for controlling a charging current, so as to achieve a relatively higher charging efficiency.
More specifically, a method for controlling a charging current in accordance with an embodiment is adapted to a charging device. The charging device receives an input voltage to thereby output the charging current. In the present embodiment, the method for controlling a charging current includes the following steps of: making the charging current have a first value; judging whether the input voltage is less than a preset reference voltage; and if the input voltage is judged to be less than the preset reference voltage, decreasing the charging current from the first value step by step until the input voltage retrieves back above the preset reference voltage.
A method for controlling a charging current in accordance with another embodiment is adapted to a charging device. The charging device receives an input voltage to thereby output the charging current. In the present embodiment, the method for controlling a charging current includes the following steps of: making the charging current increase from an initial value step by step; and after the charging current is increased with each step, judging whether the input voltage is less than a preset reference voltage; if the input voltage is judged to be less than the preset reference voltage, making the charging current retrieve back to a previous value; and if the input voltage is judged to be not less than the preset reference voltage, making the charging current continue increasing by step.
A method for controlling a charging current in accordance with still another embodiment includes the following steps of: detecting a value of the charging current; and when the detected value of the charging current is greater than a current limit value, outputting a pulse signal to control the charging current to be decreased. Herein, a pulse width of the pulse signal determines the decreased value of the charging current.
In summary, the various embodiments of the present disclosure dynamically control the charging current. On one hand, when the input voltage quickly drops caused by over-charging current, the charging current can be appropriately decreased to make the input voltage retrieve back to its normal/regular value, which can avoid terminating the charging process occurred in the prior art. On the other hand, the charging current can be increased as high as possible on the prerequisite of that the input voltage is not less than the preset reference voltage, so that a relatively higher charging efficiency compared with the prior art can be achieved.
Other objectives, features and advantages of the present disclosure will be further understood from the further technological features disclosed by the embodiments of the present disclosure wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which:
In the following detailed description of the embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. It is to be understood that other embodiment may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Accordingly, the descriptions will be regarded as illustrative in nature and not as restrictive.
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More specifically, a negative input terminal of the comparator CMP receives the input voltage VIN, and a positive input terminal of the comparator CMP receives a reference voltage VREF. The comparator CMP outputs a pulse signal VDPM according to the relative magnitude relationship between the received input voltage VIN and the reference voltage VREF. The current control loop 12 is electrically coupled between the comparator CMP and a control terminal of the charging switch CS, for controlling a working state of the charging switch CS to set the value of the charging current IBAT, and further is controlled by the pulse signal VDPM to determine a decreased amount of the charging current IBAT. The charging switch CS is electrically coupled to the comparator CMP to receive the input voltage VIN, and is controlled by the current control loop 12 to provide the charging current IBAT for charging a rechargeable battery of the electronic device. It can be found from
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Sum up, the present disclosure dynamically controls the charging current. On one hand, when the input voltage quickly drops caused by over-charging current, the charging current can be appropriately decreased to make the input voltage retrieve back to its normal/regular value, which can avoid terminating the charging process occurred in the prior art. On the other hand, the charging current can be increased as high as possible on the prerequisite of that the input voltage is not less than the preset reference voltage, so that a relatively higher charging efficiency can be achieved consequently.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.
Number | Date | Country | Kind |
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100111619 | Apr 2011 | TW | national |