Fault condition protection
First Claim
Patent Images
1. A circuit for protecting a power supply from fault conditions, comprising:
- a switching device coupled to receive a switching signal to control power delivered to an output of the power supply; and
a timer coupled to the switching device and coupled to receive a feedback signal from a feedback control loop coupled to the output of the power supply, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal, the timer disabling the switching device to prevent power delivery to the output in response to the feedback signal.
2 Assignments
2 Petitions
Accused Products
Abstract
A circuit protects a power conversion system with a feedback control loop from a fault condition. The circuit has an oscillator having an input for generating a signal with a frequency and a timer connected to the oscillator input and to the feedback control loop. The timer disables the oscillator after a period following the opening of the feedback control loop to protect the power conversion system.
51 Citations
41 Claims
-
1. A circuit for protecting a power supply from fault conditions, comprising:
-
a switching device coupled to receive a switching signal to control power delivered to an output of the power supply; and
a timer coupled to the switching device and coupled to receive a feedback signal from a feedback control loop coupled to the output of the power supply, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal, the timer disabling the switching device to prevent power delivery to the output in response to the feedback signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A method for protecting a power supply from fault conditions, comprising:
-
switching a switching device in response to a switching signal to control power delivery to an output of the power supply;
timing a feedback signal of a feedback control loop coupled to the output of the power supply to detect whether a fault condition exists in the power supply, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal; and
disabling the switching device from switching in response to the feedback signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
charging a capacitor at a first rate from a first threshold to a second threshold to generate a first period; and
discharging the capacitor from the second threshold to the first threshold at a second rate to generate a second period.
-
-
19. The method of claim 18 further comprising discharging the capacitor to a voltage below the first threshold each time the feedback signal cycles.
-
20. The method of claim 16 wherein the timing step includes counting periods of time digitally.
-
21. The method of claim 20 further comprising generating a signal which oscillates at a first frequency when the switching device is enabled and oscillates at a second frequency when the switching device is disabled.
-
22. The method of claim 15 wherein the switching device is a power transistor.
-
23. The method of claim 14 wherein the fault condition includes one or more of an output overload fault condition, an output short circuit fault condition and an open feedback control loop fault condition.
-
24. A circuit for protecting a power supply from fault conditions, comprising:
-
switching means coupled to receive a switching signal for controlling power delivered to an output of the power supply;
timing means coupled to the switching means and coupled to receive a feedback signal from a feedback control loop coupled to the output of the power supply to detect whether a fault condition exists in the power supply, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal; and
means for disabling the switching means in response to the feedback signal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33)
means for charging a capacitor at a first rate from a first threshold to a second threshold to generate a first period; and
means for discharging the capacitor from the second threshold to the first threshold at a second rate to generate a second period.
-
-
33. The circuit of claim 32 further comprising means for discharging the capacitor to a voltage below the first threshold each time the feedback signal cycles.
-
34. A fault protected power supply, comprising:
-
a transformer having a primary winding and a secondary winding coupled to a secondary output;
a switching device coupled to the primary winding of the transformer for controlling power delivered to the secondary output in response to a switching signal;
an oscillator for generating a signal with a predetermined frequency; and
a timer coupled to the oscillator and coupled to receive a feedback signal from the secondary output, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal, the timer disabling the switching device in response to the feedback signal. - View Dependent Claims (35, 36)
-
-
37. A method for protecting a power supply, comprising:
-
controlling power delivered to a secondary output of the power supply using a switching device switched in response to a switching signal and coupled to a primary winding of a transformer, the transformer having a secondary winding coupled to the secondary output;
generating an oscillating signal with a predetermined frequency;
timing a feedback signal from the secondary output with the oscillating signal, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal; and
disabling the switching device in response to the feedback signal. - View Dependent Claims (38, 39)
-
-
40. A fault protected power supply, comprising:
-
a transformer having a primary winding and a secondary winding coupled to a secondary output;
a switching device coupled to the primary winding of the transformer for controlling the power delivered to the secondary output in response to a switching signal;
a capacitor;
means for charging the capacitor at a first rate from a first threshold to a second threshold to generate a first period and discharging the capacitor from the second threshold to first threshold at a second rate to generate a second period; and
means coupled to the switching device, the capacitor and coupled to receive a feedback signal from the secondary output, for alternately enabling the switching device during first period and disabling the switching device during the second period in response to the feedback signal, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal.
-
-
41. A method for protecting a power supply, comprising:
-
controlling power delivered to a secondary output of the power supply using a switching device switched in response to a switching signal and coupled to a primary winding of a transformer, the transformer having a secondary winding coupled to the secondary output;
charging a capacitor at a first rate from a first threshold to a second threshold to generate a first period;
discharging the capacitor from the second threshold to first threshold at a second rate to generate a second period; and
alternatingly enabling the switching device during the first period and disabling the switching device during the second period in response to a feedback signal from the secondary output, the feedback signal cycling periodically between a first state and a second state when the power supply operates normally and remaining idle when the power supply is in a fault condition, the switching signal cycling separately from cycling of the feedback signal.
-
Specification