OVERCURRENT PROTECTION DEVICE

• US 20120182661A1
• Filed: 04/14/2011
• Published: 07/19/2012
• Est. Priority Date: 01/19/2011
• Status: Active Grant

• Current Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hong Fu Jin Precision Industry (Shenzhen) Co., Ltd. (Hon Hai Precision Industry Co., Ltd.), Hon Hai Precision Industry Co., Ltd.
• Inventors: LUO, QI-YAN, TONG, SONG-LIN, CHEN, PENG
• Granted Patent: US 8,854,782 B2
• Time in Patent Office: Days
• US Class Current: 361/93.7
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: H02H 3/087 for dc applications

Abstract

An overcurrent protection device includes a power input terminal, a power output terminal, a first signal terminal, a second signal terminal, a testing circuit, and a switch element. The power input terminal and the first signal terminal are connected to a power supply. The power output terminal and the second signal terminal are connected to a computer motherboard. If the first and second terminals are disconnected from each other when the computer motherboard works, the power supply stops working. The testing circuit includes a fixed resistor and a control chip parallel connected between the power input and output terminal. The control chip stores a predetermined voltage threshold, and detects voltage between the two terminals of the fixed resistor, and compares the measured voltage with the predetermined voltage threshold. The switch element disconnects the first and second signal terminals when the measured voltage is greater than the predetermined voltage threshold.

Claims

1. An overcurrent protection device, comprising:

at least one power input terminal electrically connected to a power supply, at least one power output terminal electrically connected to a computer motherboard, a first signal terminal electrically connected to the power supply, a second signal terminal electrically connected to the computer motherboard, wherein when a user inputs a power-on instruction using the second signal terminal, the first signal terminal and the second signal terminal are electrically connected to each other, causing the power supply to start to work, and if the first terminal and the second terminals are disconnected from each other when the computer motherboard works, the power supply stops working;

a testing circuit comprising a fixed resistor and a control chip which are parallel electrically connected between the power input terminal and the power output terminal, the control chip storing a predetermined voltage threshold, and configured for detecting voltage between the two terminals of the fixed resistor, and comparing the measured voltage with the predetermined voltage threshold; and

a switch element configured for disconnecting the first signal terminal and the second signal terminal when the measured voltage is greater than the predetermined voltage threshold,

2. The overcurrent protection device in claim 1, wherein the control chip comprises a voltmeter, a voltage setting module, and a comparison module, the voltmeter is configured for measuring the voltage drops across the corresponding fixed resistor, the voltage setting module is configured for presetting the voltage threshold, the comparison module is configured for comparing the voltage drop and the preset voltage threshold, to output a comparison result to the switch element.

3. The overcurrent protection device in claim 1, further comprising a variable resistor, wherein one terminal of the variable resistor is electrically connected to the power input terminal, the other terminal of the variable resistor is electrically connected to the power output terminal through the control chip, the resistance of the fixed resistor is less than resistance of the variable resistor, the voltage threshold is capable of being set through adjusting the resistance of the variable resistor.

5. The overcurrent protection device in claim 3, wherein the variable resistor is positioned in a digital rheostat, the overcurrent protecting device further comprising a microcontroller and a resistance input unit, the microcontroller is electrically connected to the digital rheostat and the resistance input unit, the resistance input unit is configured for adjusting the resistance of the variable resistor.

6. The overcurrent protection device in claim 5, wherein the resistance input unit is a matrix keyboard circuit.

7. The overcurrent protection device in claim 1, wherein the switch element comprises a first terminal, a second terminal, and a controlling terminal configured for controlling the connection or disconnection of the first terminal and the second terminal, the first terminal is the first signal terminal, the second terminal is the second signal terminal, the controlling terminal is electrically connected to the control chip.

8. The overcurrent protection device in claim 7, wherein the switch element is N-channel MOS field effect transistor, the first terminal is drain electrode, the second terminal is source electrode, the controlling terminal is gate electrode.

9. The overcurrent protection device in claim 1, wherein the power supply module comprises a first main body and a first switch, the computer motherboard comprises a second main body and a second switch, the power input terminal is electrically connected to the first main body, the first switch is electrically connected to the first signal terminal, the power output terminal is electrically connected to the second main body, the second switch is electrically connected to the second signal terminal.

10. The overcurrent protection device in claim 1, further comprising a display, wherein the display is electrically connected to the microcontroller and configured for displaying the current value passing through the fixing resistor.

4. The overcurrent protection device in claim 13, wherein the resistance of the variable resistor is proportional to the preset voltage threshold.