Battery protection circuit

1. Technical Field

The present disclosure relates to protection circuits, and particularly to a protection circuit for a battery.

2. Description of Related Art

Lithium battery is used in various electronic devices, such as a camera, a mobile phone, and a notebook computer. The lithium battery comprises a chip and a control module connected to the chip. The control module is used to detect the state of the lithium battery, and when the lithium battery is abnormal, such as overvoltage, overcurrent, or short circuit, the chip works with the control module, for protecting the lithium battery from being damaged. However, when the chip is powered up by the control module, the current sinking through the chip is usually an overcurrent which may damage the chip. Therefore, there is room for improvement within the art.

Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is a block diagram of a battery protection circuit in accordance with an embodiment.

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

The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.

FIGS. 1-2 illustrate a battery protection circuit in accordance with an embodiment comprises a power supply module 10 , a control module 30 connected to the power supply module 10 , and a loading module 40 connected to the power supply module 10 .

The power supply module 10 comprises a first switch 11 and a battery 13 . A source terminal of the first switch 11 is grounded. A drain terminal of the first switch 11 is connected to a capacitor C 1 , and the capacitor C 1 is grounded. A gate terminal of the first switch 11 is connected to the control module 30 . A positive terminal of the battery 13 is connected to a first node 130 , and a negative terminal of the battery 13 is grounded. In one embodiment, the first switch 11 is a metal-oxide-semiconductor field-effect transistor (MOSFET), and when the first switch 11 receives a high level signal, the first switch is rendered conductive, and a model of the first switch 11 is AOT266. The battery 13 is a lithium battery.

The control module 30 comprises a delay chip 31 and a second switch 33 . A pin GND of the delay chip 31 is grounded. A pin OUT of the delay chip 31 is connected to the gate terminal of the first switch 11 via a resistor R 1 . A pin CONT of the delay chip 31 is connected to a capacitor C 2 , and the capacitor C 2 is grounded. A pin TRIG of the delay chip 31 is connected to a second node 310 , and the second node 310 is grounded via a resistor R 2 . A pin THRES and a pin DISCH of the delay chip 31 are connected to the second node 310 , and the second node 310 is connected to the first node 130 via a resistor R 3 . A control terminal 17 is used to receive a control signal and connected to the first node 310 via a capacitor C 3 . The control terminal 17 is connected to a sensor (not shown). In one embodiment, the sensor, connected to the control terminal 17 and the loading module 40 , is used to detect the state of the loading module 40 . When the senor detects the loading module 40 is in a normal state, the senor can send a high level signal to the control terminal 17 so that the first switch 11 is rendered conductive. When the sensor senses he loading module 40 is in an abnormal state, such as the loading module 40 is in an overvoltage state, or the loading module 40 is in an overcurrent state, or the loading module 40 is shorted, the sensor can send a low level signal to the control terminal 17 . A pin RESET of the delay chip 31 is connected to the first node 130 . A pin VCC of the delay chip 31 is connected to the first node 130 . A base terminal of the second switch 33 is connected to the first node 130 via a resistor R 4 . An emitter terminal of the second switch 33 is grounded. A collector terminal of the second switch 33 is connected to the gate terminal of the first switch 11 via a resistor R 5 . In one embodiment, the delay chip 31 is model number NF555, and a type of the second switch 33 is an npn bipolar junction transistor. A resistance of the resistor R 2 is 100 KΩ, a resistance of the resistor R 3 is 100 KΩ, a resistance of the resistor R 4 is 10 KΩ, and a resistance of the resistor R 5 is 1 KΩ. A capacitance of the capacitor C 1 is 1.0 uF, and a capacitance of the capacitor C 2 is 0.01 uF.

A first connecting terminal of the loading module 40 is connected to the first node 130 via an inductor 43 , and a second end of the loading module 40 is grounded.

In use, the battery 13 works normally and outputs a voltage to the loading module 40 . The sensor detects the state of the loading module 40 . When the sensor detects the loading module 40 is in a normal state, the senor sends a high level to the control terminal 1 and a high level signal is outputted by the control terminal 17 . Thus, the first switch 11 can get the high level signal via the delay chip 31 and is rendered conductive. When the loading module 40 is abnormal, such as the loading module 40 is in an overvoltage state, or the loading module 40 is in an overcurrent state, or the loading module 40 is shorted, the sensor connected to the loading module 40 senses the loading module 40 is in the abnormal state. Thus, the sensor sends a low level signal to the control terminal 17 . Thus, the first switch 11 is turned off. The low level signal received by the control terminal 17 extends through the capacitor C 3 and is inputted into the delay chip 31 . The delay chip 31 can delay a time of the control terminal 17 transmitted to the first switch 11 , and the speed of switching off the first switch 11 can be decreased. Thus, the battery 13 connected to the loading module 40 , when the loading module 40 is in an overvoltage state, or the loading module 40 is in an overcurrent state, or the loading module 40 is shorted, the battery 13 is also in an overvoltage state, or the loading module 40 is in an overcurrent state, or the loading module 40 is shorted. However, the positive terminal of the battery 13 is connected to the source terminal of the first switch 11 , and the source terminal of the first switch 11 is grounded. The speed of switching off the first switch 11 is decreased, thus, a part of the overvoltage or overcurrent of the battery 13 flows into the ground, and the battery 13 can be protected via the decreased speed of the first switch 11 being turned off. In one embodiment, a withstand voltage of the first switch 11 is 60V, and a resistance of the R DS (ON) between the source terminal and the drain terminal of the first switch 11 .

It is to be understood, however, that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.