CIRCUIT COMBINING A SWITCHING REGULATOR AND AN OVERVOLTAGE DETECTION CIRCUIT

• US 20090289611A1
• Filed: 05/21/2008
• Published: 11/26/2009
• Est. Priority Date: 05/21/2008
• Status: Active Grant

• Current Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Original Assignee: Allegro Microsystems Incorporated (Sanken Electric Company Limited)
• Inventors: Chen, Weiyun, Vig, Ravi, Mangtani, Vijay
• Granted Patent: US 7,834,603 B2
• Time in Patent Office: Days
• US Class Current: 323/283
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load

Abstract

An electronic circuit combines a synchronous switching regulator circuit with an overvoltage detection circuit. The overvoltage detection circuit is configured to generate an overvoltage signal capable of an overvoltage state indicative of a power supply voltage being above a predetermined threshold voltage. The switching regulator circuit is coupled to receive the overvoltage signal. The switching regulator is also configured, in response to the overvoltage signal being in the overvoltage state, to generate a first control signal resulting in at least one of two series coupled transistors being in an off condition.

Claims

1. An electronic circuit, comprising:

a switching regulator circuit, comprising;

a first transistor having an input node, an output node, and a control node, wherein the input node of the first transistor is coupled to receive a power supply voltage;

a second transistor having an input node, an output node, and a control node, wherein the input node of the second transistor is coupled to the output node of the first transistor, wherein the output node of the second transistor is coupled to receive a reference voltage; and

a control circuit having a first output node at which a first control signal is provided and a second output node at which a second control signal is provided, wherein the first output node of the control circuit is coupled to the control node of the first transistor, and wherein the second output node of the control circuit is coupled to the control node of the second transistor; and

an overvoltage detection circuit having an input node coupled to receive the power supply voltage and an output node at which an overvoltage signal is provided capable of an overvoltage state indicative of the power supply voltage being above a predetermined threshold voltage, wherein the control circuit is coupled to receive the overvoltage signal, and wherein the control circuit is configured, in response to the overvoltage signal being in the overvoltage state, to generate the first control signal resulting in the first transistor being in an off condition.

2. The electronic circuit of claim 1, wherein the control circuit is configured, in response to the overvoltage signal being in the overvoltage state, to generate the first and second control signals resulting in the first and second transistors both being in an off condition at the same time.

3. The electronic circuit of claim 1, wherein the control circuit is configured, in response to the overvoltage signal being in the overvoltage state, to generate the first and second control signals resulting in the first transistor being in an off condition and, at the same time, the second transistor being in an on condition.

4. The electronic circuit of claim 1, wherein the first and second transistors are field effect transistors.

5. The electronic circuit of claim 1, wherein the control circuit is configured, in response to the overvoltage signal not being in the overvoltage state, to generate the first and second control signals as respective complimentary periodic signals resulting in the first and second transistors being in respective complimentary periodic on and off conditions.

6. The electronic circuit of claim 1, wherein the control circuit is configured, in response to the overvoltage signal not being in the overvoltage state, to generate, during first periodic time periods, the first and second control signals as respective complimentary signals resulting in the first and second transistors being in respective complimentary on and off conditions, and to generate, during second periodic time periods, the first and second control signals resulting in at least one of the first or second transistors being in the off condition.

7. The electronic circuit of claim 1, further comprising a voltage regulator circuit having an input node coupled to receive the power supply voltage and configured to generate a regulated voltage at an output node regardless of any state of the overvoltage signal.

8. The electronic circuit of claim 7, wherein the control circuit further comprises a power input node coupled to receive the regulated voltage.

9. The electronic circuit of claim 7, wherein the overvoltage detection circuit further comprises a power input node configured to receive the regulated voltage.

10. The electronic circuit of claim 1, wherein the switching regulator circuit further comprises:

an inductor having first and second nodes, the first node of the inductor coupled to the output node of the first transistor and to the input node of the second transistor; and

a capacitor coupled to the second node of the inductor, wherein the control circuit further comprises a feedback node coupled to the second node of the inductor, and wherein a switched-regulated voltage is provided at the second node of the inductor.

11. The electronic circuit of claim 1, wherein the switching regulator circuit further comprises:

an inductor having first and second nodes, the first node of the inductor coupled to the output node of the first transistor and to the input node of the second transistor;

a third transistor having an input node, an output node, and a control node, wherein the input node of the third transistor is coupled to the second node of the inductor and wherein the output node of the third transistor is coupled to receive the reference voltage;

a fourth transistor having an input node, an output node, and a control node, wherein the output node of the fourth transistor is coupled to the second node of the inductor and to the input node of the third transistor; and

a capacitor having a node coupled to the input node of the fourth transistor, wherein the control circuit further comprises a feedback node coupled to the node of the capacitor, and wherein a regulated voltage is provided at the node of the capacitor, wherein the control circuit further has a third output node at which a third control signal is provided and a fourth output node at which a fourth control signal is provided, wherein the third output node of the control circuit is coupled to the control node of the third transistor, and wherein the fourth output node of the control circuit is coupled to the control node of the fourth transistor.

12. The electronic circuit of claim 1, wherein the overvoltage detection circuit further comprises an enable input node coupled to receive an enable signal, wherein the overvoltage detection circuit is configured to generate the overvoltage signal not in the overvoltage state in response to a state of the enable signal.

13. A method of controlling a switching regulator circuit, the switching regulator circuit comprising:

a first transistor having an input node, an output node, and a control node, wherein the input node of the first transistor is coupled to receive a power supply voltage;

a second transistor having an input node, an output node, and a control node, wherein the input node of the second transistor is coupled to the output node of the first transistor, wherein the output node of the second transistor is coupled to receive a reference voltage; and

a control circuit having a first output node at which a first control signal is provided and a second output node at which a second control signal is provided, wherein the first output node of the control circuit is coupled to the control node of the first transistor and wherein the second output node of the control circuit is coupled to the control node of the second transistor, the method comprising;

detecting if the power supply voltage is above a predetermined threshold voltage; and

in response to the detecting, turning off the first transistor.

14. The method of claim 13, wherein the turning off the first transistor comprises turning off the first and second transistors at the substantially same time.

15. The method of claim 13, wherein the turning off the first transistor comprises turning off the first transistor and turning on the second transistor at substantially the same time.

16. The method of claim 13, further comprising:

generating a regulated voltage regardless of the turning off the first transistor.

17. The method of claim 16, wherein the control circuit further comprises a power input node coupled to receive the regulated voltage.

18. The method of claim 16, wherein the detecting comprises detecting by use of the regulated voltage regardless of the turning off the first transistor.

19. The method of claim 13, wherein the switching regulator circuit further comprises:

an inductor having first and second nodes, the first node coupled to the output node of the first transistor and to the input node of the second transistor; and

a capacitor coupled to the second node of the inductor, wherein the control circuit further comprises a feedback node coupled to the second node of the inductor, and wherein a switched-regulated voltage is provided at the second node of the inductor.

20. The method of claim 13, wherein the switching regulator circuit further comprises:

an inductor having first and second nodes, the first node of the inductor coupled to the output node of the first transistor and to the input node of the second transistor;

a third transistor having an input node, an output node, and a control node, wherein the input node of the third transistor is coupled to the second node of the inductor and wherein the output node of the third transistor is coupled to receive the reference voltage;

a fourth transistor having an input node, an output node, and a control node, wherein the output node of the fourth transistor is coupled to the second node of the inductor and to the input node of the third transistor; and

a capacitor having a node coupled to the input node of the fourth transistor, wherein the control circuit further comprises a feedback node coupled to the node of the capacitor, and wherein a regulated voltage is provided at the node of the capacitor, wherein the control circuit further has a third output node at which a third control signal is provided and a fourth output node at which a fourth control signal is provided, wherein the third output node of the control circuit is coupled to the control node of the third transistor, and wherein the fourth output node of the control circuit is coupled to the control node of the fourth transistor.