Short-circuit protection system for power converters

• US 9,419,431 B2
• Filed: 05/14/2014
• Issued: 08/16/2016
• Est. Priority Date: 05/14/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Prexl, Franz, De Martino, Mariangela
• Primary Examiner(s): Tran, Thienvu
• Assistant Examiner(s): Comber, Kevin J
• Application Number:
  US14/277,294
• Publication Number:
  US 20150333502A1
• Time in Patent Office: 825 Days
• Field of Search: 361/18
• US Class Current: 1/1
• CPC Class Codes: H02H 7/1213 for DC-DC converters
• CPC Class Codes: H02M 1/325 with means for allowing continuous operation despite a fault, i.e. fault tolerant converters
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence

Abstract

One example includes a power converter system. The system includes a switching circuit configured to activate at least one power supply switch in response to a driver signal to provide an output voltage at an output based on an input voltage at an input and based on an inductor current associated with an inductor. The at least one power supply switch includes a parasitic diode that interconnects the inductor and the output. The system also includes a short-circuit protection system configured to detect a short-circuit condition and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition to provide the inductor current from the inductor to the output through the parasitic diode in response to the deactivation of the at least one power supply switch.

Claims

1. A power converter system comprising:

a switching circuit configured to activate at least one power supply switch in response to a driver signal to provide an output voltage at an output based on an input voltage at an input and based on an inductor current associated with an inductor, the at least one power supply switch comprising a parasitic diode and interconnecting the inductor and the output; and

a short-circuit protection system configured to detect a short-circuit condition and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition to provide the inductor current from the inductor to the output through the parasitic diode in response to the deactivation of the at least one power supply switch, the parasitic diode increasing a voltage difference across the power supply switch thereby allowing a variable duty cycle of the switching circuit that is at a greater value than a minimum acceptable value.

2. The system of claim 1, wherein the switching circuit comprises a gate driver configured to control the at least one power supply switch in response to the driver signal, wherein the short-circuit protection system comprises an amplifier configured to provide a short-circuit condition signal in response to the output voltage decreasing to less than a threshold, the short-circuit condition signal being provided to the gate driver to hold the at least one power supply switch in a deactivated state based on the short-circuit condition signal.

3. The system of claim 2, wherein the short-circuit protection system further comprises:

a resistor interconnecting the input voltage and an input of the amplifier; and

a detection switch interconnecting the input of the amplifier and a low-voltage rail and which is controlled by the output voltage, such that the output voltage deactivates the detection switch in response to decreasing to less than the threshold to cause the amplifier to provide the short-circuit condition signal.

4. The system of claim 1, wherein the at least one power supply switch comprises an output power supply switch configured to provide the output voltage at the output based on the inductor current in response to the driver signal, the system further comprising an input power supply switch interconnecting the input and the inductor and being configured to activate at a variable duty-cycle to provide the inductor current through the inductor, wherein the output power supply switch is configured to be held in a deactivated state in response to the detection of the short-circuit condition to maintain the activation of the input power supply switch at the variable duty-cycle to maintain the inductor current through the inductor.

5. The system of claim 4, wherein the output power supply switch comprises a parasitic diode that is configured to conduct the inductor current when the output power supply switch is held in the deactivated state to increase a voltage difference across the output power supply switch between the inductor to the output, such that the input power supply switch can continue to be activated at the variable duty-cycle to maintain the inductor current through the inductor and through the parasitic diode.

6. The system of claim 4, wherein the input power supply switch is a first input power supply switch and the output power supply switch is a first output power supply switch, wherein the power converter system is configured as a buck-boost converter further comprising:

a second input power supply switch interconnecting a first inductor node and a low-voltage power rail, the first inductor node being coupled to the first input power supply switch; and

a second output power supply switch interconnecting a second inductor node and the low-voltage power rail, the second inductor node being coupled to the first output power supply switch.

7. The system of claim 6, wherein the short-circuit protection system is further configured to hold the second input power supply switch in a deactivated state in response to the detection of the short-circuit condition to provide the activation of the first input power supply switch at the variable duty-cycle to maintain the inductor current through the inductor.

8. The system of claim 1, wherein the short-circuit condition is associated with an initial power-up of the power converter system during which the output voltage has an initial amplitude of approximately zero volts and an associated output capacitor that is coupled to the output is initially discharged, such that the switching circuit is configured to activate a first power supply switch to charge the output capacitor and increase the output voltage based on the short-circuit protection system deactivating a second power supply switch to provide the inductor current from the inductor to the output through the parasitic diode during a soft-start operation.

9. A power converter system comprising:

a switching circuit configured to activate at least one power supply switch in response to a driver signal to provide an output voltage at an output based on an input voltage at an input and based on an inductor current associated with an inductor, the at least one power supply switch comprising a parasitic diode and interconnecting the inductor and the output; and

a short-circuit protection system configured to detect a short-circuit condition and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition to provide the inductor current from the inductor to the output through the parasitic diode in response to the deactivation of the at least one power supply switch wherein the short-circuit protection system comprises;

a first short-circuit protection system configured to detect a short-circuit condition associated with the output and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition associated with the output to provide the inductor current from the input to the output through the parasitic diode; and

a second short-circuit protection system configured to detect a short-circuit condition associated with the input and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition associated with the input to prevent the inductor current from flowing from the output to the input, wherein the second short-circuit protection system comprises;

a reference switch coupled to a detection node and being controlled by a predetermined reference voltage;

at least one switch interconnecting the input and the reference switch; and

a latching switch being controlled by the detection node, the latching switch and the at least one switch being arranged as a latch with respect to setting the detection node at a logic-high state in response to the input voltage being greater than a predetermined threshold that is associated with the reference voltage.

10. The system of claim 9, wherein the detection node is coupled to a gate driver configured to control the at least one power supply switch in response to the driver signal, and wherein the second short-circuit protection circuit is configured to set the detection node to a logic-low state in response to the input voltage decreasing less than the predetermined threshold.

11. A power converter system comprising:

a switching circuit comprising;

a first power supply switch interconnecting an input having an input voltage and an inductor and being configured to activate at a variable duty-cycle to provide an inductor current through the inductor; and

a second power supply switch interconnecting the inductor and the output and being configured to provide an output voltage at an output based on the inductor current; and

a short-circuit protection system configured to detect a short-circuit condition associated with the output and to hold the second power supply switch in a deactivated state in response to the detection of the short-circuit condition wherein the output current flows through a parasitic diode of the second switch, the parasitic diode increasing a voltage difference across an output of the power converter system to enable the activation of the first power supply switch at the variable duty-cycle that is greater than a minimum acceptable value to maintain the inductor current through the inductor during the short-circuit condition.

12. The system of claim 11, wherein the second power supply switch comprises a parasitic diode that is configured to conduct the inductor current from the inductor to the output when the second power supply switch is held in the deactivated state to increase a voltage difference across the second power supply switch between the inductor to the output, to enable the first power supply switch to be activated at the variable duty-cycle to maintain the inductor current through the inductor and through the parasitic diode.

13. The system of claim 11, wherein the power converter system is configured as a buck-boost converter further comprising:

a third power supply switch interconnecting a first inductor node and a low-voltage power rail, the first inductor node being coupled to the first power supply switch; and

a fourth power supply switch interconnecting a second inductor node and the low-voltage power rail, the second inductor node being coupled to the second power supply switch.

14. The system of claim 13, wherein the short-circuit protection system is further configured to hold the third power supply switch in a deactivated state in response to the detection of the short-circuit condition to maintain the activation of the first power supply switch at the variable duty-cycle to maintain the inductor current through the inductor.

15. The system of claim 11, wherein the switching circuit comprises a gate driver configured to control the second power supply switch in response to a driver signal, wherein the short-circuit protection system comprises an amplifier configured to provide a short-circuit condition signal in response to the output voltage decreasing to less than a threshold, the short-circuit condition signal being provided to the gate driver to hold the second power supply switch in the deactivated state.

16. The system of claim 15, wherein the short-circuit protection system further comprises:

a resistor interconnecting the input voltage and an input of the amplifier; and

a switch that interconnects the input of the amplifier and a low-voltage rail and which is controlled by the output voltage, such that the output voltage deactivates the switch in response to decreasing to less than the threshold to cause the amplifier to provide the short-circuit condition signal.

17. A power converter system comprising:

a switching circuit configured to activate at least one power supply switch in response to a driver signal to provide an output voltage at an output based on an input voltage at an input and based on an inductor current associated with an inductor, the at least one power supply switch comprising a parasitic diode and interconnecting the inductor and the output; and

a first short-circuit protection system configured to detect a short-circuit condition associated with the output and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition associated with the output to provide the inductor current from the inductor to the output through the parasitic diode during at least a portion of the short-circuit condition associated with the output; and

a second short-circuit protection system configured to detect a short-circuit condition associated with the input and to deactivate the at least one power supply switch in response to the detection of the short-circuit condition associated with the input to prevent the inductor current from flowing from the output to the input, wherein the second short-circuit protection system comprises;

a reference switch coupled to a detection node and being controlled by a predetermined reference voltage;

at least one switch interconnecting the input and the reference switch; and

a latching switch being controlled by the detection node, the latching switch and the at least one switch being arranged as a latch with respect to setting the detection node at a logic-high state in response to the input voltage being greater than a predetermined threshold that is associated with the reference voltage.

18. The system of claim 17, wherein the switching circuit comprises a gate driver configured to control the second power supply switch in response to a driver signal, wherein the short-circuit protection system comprises:

an amplifier configured to provide a short-circuit condition signal in response to the output voltage decreasing to less than a threshold, the short-circuit condition signal being provided to the gate driver to hold the at least one power supply switch in a deactivated state;

a resistor interconnecting the input voltage and an input of the amplifier; and

a switch interconnecting the input of the amplifier and a low-voltage rail and which is controlled by the output voltage, such that the output voltage deactivates the switch in response to decreasing less than the threshold to cause the amplifier to provide the short-circuit condition signal.