Protection structure for battery charging

1. Technical Field

The disclosure relates to batteries, and particularly, to a protection structure for battery charging.

2. Description of Related Art

A typical lithium battery used in a portable electronic device such as a mobile phone or a laptop computer, often includes a protection circuit for charging. Generally, the protection circuit includes a thermal resistor, a microprocessor, and a charging control sub-circuit connected to the microprocessor. The thermal resistor senses the battery's temperature when in charging, the microprocessor controls the sub-circuit to charge according to the sensed temperature. If the temperature is higher than a reference value, the microprocessor can control the sub-circuit to stop charging to protect the battery from being over-charged. However, the microprocessor may malfunction at times, and the battery cannot be charged safely.

Therefore, it is desirable to provide a battery protection structure, which can overcome the problems described above.

FIG. 1 is a functional block diagram of a battery protection structure, according to an exemplary embodiment.

FIG. 2 is a circuit diagram of the battery protection structure of FIG. 1 .

Referring to FIGS. 1 and 2 , a protection structure 100 for battery charging includes a temperature sensing module 10 , a processing module 20 , and a charging control module 30 . The temperature sensing module 10 is configured for sensing the temperature of a battery 200 when charging, and further converting the temperature values into electronic signals. The processing module 20 is configured for receiving the electronic signals from the temperature sensing module 10 and outputting a first control signal group according to the values of the electronic signals. The charging control module 30 includes a comparing sub-module 31 and an executing sub-module 32 . The comparing sub-module 31 is configured for receiving the electronic signals from the temperature sensing module 10 and outputting a second control signal group according to the electronic signals. The executing sub-module 32 is configured for recognizing and comparing the first control signal group with the second control signal group. The executing sub-module 32 further controls the battery 200 to charge or stop charging according to the first control signal group, when the second control signal group is consistent with the first control signal group. The executing sub-module 32 also controls the battery 200 to charge or stop charging according to the second control signal group, when the second control signal group is opposite to the first control signal group.

In detail, the temperature sensing module 10 includes a thermal sensor 11 embedded in or attached to the battery 200 . The thermal sensor 11 can sense the current temperature of the battery 200 and output the electronic signals corresponding to the current temperature. In the present embodiment, the electronic signal is a voltage.

The processing module 20 is connected to the temperature sensing module 10 and continuously receives the electronic signals from the temperature sensing module 10 . The processing module 20 predetermines a number of first reference ranges corresponding to the electronic signals and is configured for judging the relationship between the first reference ranges and the electronic signals. For example, the processing module 20 can predetermine one range from about 2V to about 5V corresponding to the output of a charging signal, another range from about 3V to about 4V corresponding to the output of a charging signal with constant current, and another range lower than about 2V and higher than about 5V to output a stop-charging signal. If the value of the electronic signal is about 3.5 V, the processing module 20 confirms that the electronic signal is fallen in the range of about 3V to about 4V, and outputs a first control signal group including a constant current charging signal to the charging control module 30 .

The comparing sub-module 31 is connected to the temperature sensing module 10 and also continuously receives the electronic signals from the temperature sensing module 10 . The comparing sub-module 31 predetermines a second reference range and is configured for judging the relationship between the second reference range and the electronic signals. For example, the comparing sub-module 31 can predetermine a second reference range from about 3V to about 5V. If the values of the electronic signals are fallen in the second reference range, the second control signal group should include a charging signal. If the values of the electronic signals are out of the first reference range, the second control signal group should include a stop-charging signal.

The executing sub-module 32 includes but is not limited to a recognizing unit 321 , a comparing unit 323 , and a generating unit 325 .

The recognizing unit 321 is configured for recognizing and converting the second control signal group and the first control signal group to be readable in same form characters. In the present embodiment, when the recognizing unit 321 recognizes the first control signal group including a charging signal, a character “001” is output. When the recognizing unit 321 recognizes the first control signal group including a stop-charging signal, a character “000” is output. When the recognizing unit 321 recognizes the first control signal group including a constant current charging signal, a character “011” is output. When the recognizing unit 321 recognizes the second control signal group including a charging signal, a character “1” is output. When the recognizing unit 321 recognizes the second control signal group including a stop-charging signal, a character “0” is output. It is understood that the form of the readable character cannot be limited in digital form as described above.

The comparing unit 323 is configured for comparing the output characters corresponding to the second control signal group with the output characters corresponding to the first control signal group, and judging whether the first and second control signal group both include a charging signal or a stop-charging signal. In the present embodiment, the comparing unit 323 compares the end character of the first control signal with the primary character of the second control signal. If the end character of the first control signal is the same as the primary character of the second control signal, the comparing unit 323 confirms that the first and second control signal group are consistent with each other and outputs an “enable” signal to the generating unit 325 . If the end character of the first control signal is different from the primary character of the second control signal, the comparing unit 323 judges that the first and second control signal group are opposite to each other and outputs a “disable” signal to the generating unit 325 .

The “enable” signal to show that the processing module 20 is in an enabled state while the “disable” signal shows that the processing module 20 is in a disabled state for the following reasons: the processing module 20 is a semiconductor chip for running a program while the comparing sub-module 31 is a hardware circuit. As a result, compared to the comparing sub-module 31 , the processing module 20 is easier to shut down due to an error message from the program. As such, when the second control signal output from the processing module 20 has the opposite result as the first control signal output from the comparing sub-module 31 , the processing module 20 is considered to have malfunctioned. Therefore, it is reasonable to judge the “enable” or “disable” state of the processing module 20 according to the comparison results from the comparing unit 323 .

The generating unit 325 is configured for charging the battery 200 or stop charging according to the first control signal while the comparing unit 323 outputs “enable” signal, and for charging or stop charging according to the second control signal while the comparing unit 323 outputs a “disable” signal.

Referring to FIG. 2 , a circuit diagram of the battery protection structure 100 for charging the battery 200 is shown. The temperature sensing module 10 further includes a constant resistor 13 connected to one end of the thermal resistor 11 in series. The other end of the thermal resistor 11 is grounded. The other end of the constant resistor 13 is connected to the charging control module 30 , the processing module 20 , and a reference end 15 at the same time. The reference end 15 is connected to a first power source 17 for receiving a constant voltage drop. In the present embodiment, the constant voltage drop is about 3.3V. An adjustable resistor 19 is connected to a node between the reference end 15 and the constant resistor 13 . As such, the output voltage of the temperature sensing module 10 is changeable with the temperature changing and equal to the sum of the voltage dropped on the constant resistor 13 and the thermal resistor 11 .

The charging control module 30 includes a detecting terminal 301 , a first input terminal 302 for inputting the reference voltage, a second input terminal 303 for inputting the voltage drop from a second power source 300 , a first output terminal 304 for outputting the voltage drop from the second power source 300 to the battery 200 , and two comparators 305 . Each comparator 305 includes two third input terminals 305 a and a second output terminal 305 b . The detecting terminal 301 connects the constant resistor 13 to one of the third input terminals 305 a of each comparator 305 . The first input terminal 302 connects the reference end 15 to the other third input terminal 305 a of each comparator 305 .

The generating unit 325 includes at least one field effective transistor 325 a (FET). The second output terminal 305 b is connected to the gate of the FET 325 a via the recognizing unit 321 and the comparing unit 323 . The second input terminal 303 connects the source of the FET 325 a to the second power source 300 . The first output terminal 304 connects the drain of the FET 325 a to the battery 200 .

The processing module 20 includes a fourth input terminal 21 and a third output terminal 23 . The fourth input terminal 21 is connected to a node between the constant resistor 13 and the adjustable resistor 19 for receiving the output from the thermal sensor 11 . The third output terminal 23 is connected to the recognizing unit 321 for outputting the first control signal group thereto.

When the comparator 305 receives the electronic signals from the temperature sensing module 10 and the second reference range from the first input terminal 302 , the comparator 305 compares the second reference range and the electronic signals. If the electronic signals are included in the second reference range, the second output terminal 305 b outputs the second control signal group including charging signal. If the electronic signals are out of the second reference range, the second output terminal 305 b outputs the second control signal group, which includes stop-charging signal, to the recognizing unit 321 . Simultaneously, the fourth input terminal 21 of the processing module 20 receives the electronic signals from the temperature sensing module 10 , and the processing module 20 judges the corresponding relationship between the first reference ranges and the electronic signals, and outputs the corresponding first control signal group from the third output terminal 23 to the recognizing unit 321 . The recognizing unit 321 recognizes the second control signal group and the first control signal group, and further outputs both groups to the comparing unit 323 . The comparing unit 323 compares the first and second control signal group and outputs a corresponding result as describe above. In this case, even the processing module 20 has malfunctioned, the battery 200 is controlled by the second control signal group and will not be overcharged.

While various exemplary and preferred embodiments have been described, it is to be understood that the disclosure is not limited thereto. To the contrary, various modifications and similar arrangements (as would be apparent to those skilled in the art) are intended to also be covered. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.