POWER PROTECTION CIRCUIT

• US 20120033333A1
• Filed: 09/14/2010
• Published: 02/09/2012
• Est. Priority Date: 08/04/2010
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: TSAI, HSIAO-JEN
• Granted Patent: US 8,467,156 B2
• Time in Patent Office: Days
• US Class Current: 361/18
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection

Abstract

A power protection circuit includes a power providing unit, a first and second voltage converters, a first and second switches, a first and second voltage detecting circuits, and a first and second warning circuits. The first switch connects between the power providing unit and the first voltage converter. The second switch connects between the power providing unit and the second voltage converter. The first and second voltage detecting circuits are respectively connected to the first and second voltage converters. The first and second warning circuits are respectively connected to the first and second voltage detecting circuits. When the input voltage of the first voltage detecting circuit drops, the first switch turns off the first voltage converter, the first warning circuit signals a warning; when the input voltage of the second voltage detecting circuit drops, the second switch turns off the second voltage converter, the second warning circuit signals a warning.

Claims

1. A power protection circuit, comprising:

a power providing unit configured for providing power supply;

a first voltage converter;

a first switch interconnected between the power providing unit and the first voltage converter;

a second voltage converter;

a second switch interconnected between the power providing unit and the second voltage converter;

a first voltage detecting circuit connected to the first voltage converter and the first switch;

a second voltage detecting circuit connected to the second voltage converter and the second switch;

a first warning circuit connected to the first voltage detecting circuit; and

a second warning circuit connected to the second voltage detecting circuit;

wherein when the input voltage of the first voltage detecting circuit drops, the first switch turns off the first voltage converter, and the first warning circuit signals a warning;

when the input voltage of the second voltage detecting circuit drops, the second switch turns off the second voltage converter, and the second warning circuit signals a warning.

2. The power protection circuit of claim 1, wherein the first switch comprises a first transistor, the second switch comprises a second transistor, when the input voltage of the first voltage detecting circuit drops, the first switch turns off the first voltage converter, when the input voltage of the second voltage detecting circuit drops, the second switch turns off the second voltage converter.

3. The power protection circuit of claim 2, wherein both the first switch and the second switch are PMOS transistors, the drain of the first transistor is connected to an input of the first voltage converter, the gate of the first transistor is grounded, the source of the first transistor is connected to the power providing unit, the drain of the second transistor is connected to an input of the second voltage converter, the gate of the second transistor is grounded, the source of the second transistor is connected to the power providing unit.

4. The power protection circuit of claim 3, wherein the first voltage detecting circuit comprises a third transistor and a fourth transistor, both the third transistor and the fourth transistor are NPN transistors, the collector of the third transistor is connected to the gate of the first transistor, the emitter of the third transistor is grounded, the base of the third transistor is connected to an output of the first voltage converter, the collector of the fourth transistor is connected to the power providing unit, the emitter of the fourth transistor is grounded, the base of the fourth transistor is grounded, the collector of the third transistor is connected to the collector of the fourth transistor.

5. The power protection circuit of claim 3, wherein the second voltage detecting circuit comprises a fifth transistor and a sixth transistor, both the fifth transistor and the sixth transistor are NPN transistors, the collector C of the fifth transistor is connected to the gate of the second transistor, the emitter of the fifth transistor is grounded, the base of the fifth transistor is connected to an output of the second voltage converter, the collector of the sixth transistor is connected to the power providing unit, the emitter of the sixth transistor is grounded, the base of the sixth transistor is grounded, the collector of the fifth transistor is connected to the collector of the sixth transistor.

6. The power protection circuit of claim 4, wherein the first warning circuit comprises a seventh transistor, a eighth transistor, a ninth transistor, and a first light-emitting diode, the seventh transistor is an NPN transistor, both the eighth transistor and the ninth transistor are NMOS transistors, the base of the seventh transistor is connected to the collector of the third transistor, the collector of the seventh transistor is connected to the power providing unit, the emitter of the seventh transistor is connected to the collector of the fourth transistor, both gates of the eighth transistor and the ninth transistor are connected to the collector of the fourth transistor, the source of the eighth transistor is connected to the drain of the ninth transistor, the drain of the eighth transistor is connected to the cathode of the first light-emitting diode, the source of the ninth transistor is grounded, the anode of the first light-emitting diode is connected to the power providing unit.

7. The power protection circuit of claim 5, wherein the second warning circuit comprises a tenth transistor, an eleventh transistor, a twelfth transistor, and a second light-emitting diode, the tenth transistor is an NPN transistor, both the eleventh transistor and the twelfth transistor are NMOS transistors, the base of the tenth transistor is connected to the collector of the fifth transistor, the collector of the tenth transistor is connected to the power providing unit, the emitter of the tenth transistor is connected to the collector of the sixth transistor, both gates of the eleventh transistor and the twelfth transistor are respectively connected to an node formed between the source of the eighth transistor and drain of the ninth transistor, the source of the eleventh transistor is connected to the drain of the twelfth transistor, the drain of the twelfth transistor is connected to the cathode of the second light-emitting diode, the source of the twelfth transistor is grounded, the anode of the second light-emitting diode is connected to the power providing unit.

8. The power protection circuit of claim 3, wherein the gate of the first transistor is grounded by a first delay capacitance.

9. The power protection circuit of claim 3, wherein the gate of the second transistor is grounded by a second delay capacitance.

10. A power protection circuit, comprising:

a power providing unit configured for providing power supply;

a voltage converter;

a switch interconnected between the power providing unit and the voltage converter; and

a voltage detecting circuit connected to the voltage converter and the switch;

wherein the switch is configured to turn the voltage converter off upon a condition that the input voltage of the voltage detecting circuit drops.

11. The power protection circuit of claim 10, further comprising a warning circuit connected to the voltage detecting circuit, wherein the warning circuit is configured to signal a warning upon a condition that the input voltage of the voltage detecting circuit drops.