FAULT TOLERANT POWER SUPPLY INCORPORATING INTELLIGENT GATE DRIVER-SWITCH CIRCUIT TO PROVIDE UNINTERRUPTED POWER

• US 20140268939A1
• Filed: 07/24/2013
• Published: 09/18/2014
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Alpha & Omega Semiconductor, Ltd.
• Original Assignee: Alpha & Omega Semiconductor, Ltd.
• Inventors: Tomas, Mark, Zhang, Zhiye, Chang, Allen, Chang, Kuang Ming, Lee, Gilbert
• Granted Patent: US 9,106,075 B2
• Time in Patent Office: Days
• US Class Current: 363/50
• CPC Class Codes: H02H 7/1225 responsive to internal faults, e.g. shoot-through avoiding shoot-through H02M1/38
• CPC Class Codes: H02H 9/02 responsive to excess current current limitation for voltage regulators G05F1/573; disconnection after limiting H02H3/025
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

A fault tolerant power supply system includes at least one load switch configured to connect an input voltage to an output node of the load switch when the load switch is turned on and at least one power channel coupled to the load switch to receive the input voltage. The power channel is configured as a buck converter and includes at least a high-side power switch and a low-side power switch. The fault tolerant power supply system is configured to measure a current flowing through the low-side power switch, to determine that the current flowing through the low-side power switch has exceeded a current limit threshold, and to disable the low-side power switch and the load switch in response to the determination that the current flowing in the low-side power switch has exceeded the current limit threshold.

Claims

1. A fault tolerant power supply system, the power supply system receiving an input voltage and generating an output voltage on an output voltage node, the power supply system comprising:

one or more load switches, each load switch having an input node coupled to the input voltage and an output node, the load switch providing the input voltage on the output node when the load switch is turned on and the load switch disconnecting the input voltage from the output node when the load switch is turned off; and

a plurality of power channels, each power channel having an input terminal coupled to the output node of one of the load switches and an output terminal coupled to the output voltage node of the power supply system, each power channel comprising a driver circuit, a high-side power switch and a low-side power switch connected in series, and an output inductor, the power channel and an output capacitor connected between the output voltage node and a ground potential forming a buck converter,

wherein each power channel of the plurality of power channels further comprises a current sense circuit to measure a current flowing in the low-side power switch, the current sense circuit being configured to generate a first output signal having a first state when the current flowing in the low-side power switch has a peak current value exceeding a current limit threshold, the first output signal being coupled to the driver circuit to disable the low-side power switch of the respective power channel in response to the first output signal has the first state, the first output signal further being coupled to the load switch associated with the respective power channel to turn off the load switch in response to the first output signal has the first state.

2. The fault tolerant power supply system of claim 1, wherein each load switch of the one or more load switches has an output node coupled to the input terminal of one or more power channels.

3. The fault tolerant power supply system of claim 1, wherein each load switch comprises a main switch having an input terminal connected to the input node and an output terminal connected to the output node and a control terminal, and a rapid switch turn-off circuit configured to receive the first output signal and to drive the control terminal of the main switch, the rapid switch turn-off circuit being configured to turn off the main switch in response to the first output signal having the first state.

4. The fault tolerant power supply system of claim 3, wherein the rapid switch turn-off circuit comprises a driver capable of turning off the main switch within a time duration to avoid damage to the power supply system.

5. The fault tolerant power supply system of claim 3, wherein the rapid switch turn-off circuit comprises a driver capable of turning off the main switch within a time duration in the nano-seconds range.

6. The fault tolerant power supply system of claim 1, wherein the output capacitor comprises a single output capacitor coupled to the output voltage node.

7. The fault tolerant power supply system of claim 1, wherein the current sense circuit comprises:

a peak current detector coupled to the low-side power switch and configured to measure a current flowing through the low-side power switch and to generate an output signal indicative of a peak current value of the current flowing through the low-side power switch; and

a comparator configured to compare the output signal of the peak current detector to the current limit threshold, the comparator generating the first output signal having the first state in response to the output signal of the peak current detector exceeding the current limit threshold.

8. The fault tolerant power supply system of claim 1, wherein the first output signal comprises an active high signal and the first state comprises a logical high state, the power supply system further comprises:

an open-drain NMOS transistor having a gate terminal coupled to the first output signal, a source terminal coupled to the ground potential, and a drain terminal providing a second output signal, the second output signal being coupled to the load switch associated with the respective power channel to turn off the load switch in response to the first output signal has the first state.

9. The fault tolerant power supply system of claim 1, wherein the high-side power switch and the low-side power switch comprise MOS transistors.

10. The fault tolerant power supply system of claim 1, further comprising:

a multi-phase controller configured to generate control signals for the plurality of power channels to control the duty cycle of the power channels.

11. A method in a power supply system, the power supply system receiving an input voltage and generating an output voltage on an output voltage node, the power supply system including at least one load switch configured to connect the input voltage to an output node of the load switch when the load switch is turned on and at least one power channel coupled to the load switch to receive the input voltage, the power channel being configured as a buck converter and including at least a high-side power switch and a low-side power switch, the method comprising:

measuring a current flowing through the low-side power switch;

determining that the current flowing through the low-side power switch has exceeded a current limit threshold; and

disabling the low-side power switch of the power channel and the load switch in response to the determining.

12. The method of claim 11, wherein disabling the load switch comprises:

turning off the load switch in response to the determining to disconnect the input voltage from the output node of the load switch.

13. The method of claim 12, wherein turning off the load switch in response to the determining comprises:

turning off the load switch in response to the determining within a time duration to avoid damage to the power supply system.

14. The method of claim 12, wherein turning off the load switch in response to the determining comprises:

turning off the load switch in response to the determining within a time duration in the nano-seconds range.