Multiple output power supply having soft start protection for load over-current or short circuit conditions
First Claim
1. A switching mode power converter, comprising:
- a transformer having a primary winding and a plurality of secondary windings, said plurality of secondary windings providing respective plural outputs through respective rectifiers;
a switch connected in series with said primary winding;
an input voltage source coupled to said primary winding;
a controller adapted to control operation of said switch to control a flow of current through said primary winding, said controller including a feedback circuit to determine a duty cycle of said switch in response to a detected output voltage of at least one of said plural outputs and a detected current through said primary winding, said controller further including a soft-start circuit used to inhibit activation of said switch for a predetermined period of time; and
an over-current protection circuit coupled to said plural outputs so as to detect a change in a voltage of any one of said plural outputs due to a load over-current or short circuit condition, wherein upon detection of said voltage change, said over-current protection circuit activates said soft-start circuit to shut off delivery of said flow of current through said primary winding for said predetermined period of time.
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Accused Products
Abstract
A protection circuit for a multiple output switching mode power converter protects against an over-current or short circuit failure condition. The protection circuit activates the soft-start circuit of the PWM control circuit upon detection of the over-current or short circuit condition. The soft-start circuit then shuts off operation of the power converter and restarts the power converter after a period of time defined by the soft-start circuit. The protection circuit is effective with any type of power converter topology (e.g., buck, boost, flyback, and forward converter), isolated or non-isolated, having dual or multiple outputs.
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Citations
20 Claims
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1. A switching mode power converter, comprising:
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a transformer having a primary winding and a plurality of secondary windings, said plurality of secondary windings providing respective plural outputs through respective rectifiers;
a switch connected in series with said primary winding;
an input voltage source coupled to said primary winding;
a controller adapted to control operation of said switch to control a flow of current through said primary winding, said controller including a feedback circuit to determine a duty cycle of said switch in response to a detected output voltage of at least one of said plural outputs and a detected current through said primary winding, said controller further including a soft-start circuit used to inhibit activation of said switch for a predetermined period of time; and
an over-current protection circuit coupled to said plural outputs so as to detect a change in a voltage of any one of said plural outputs due to a load over-current or short circuit condition, wherein upon detection of said voltage change, said over-current protection circuit activates said soft-start circuit to shut off delivery of said flow of current through said primary winding for said predetermined period of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a switching mode power converter comprising plural outputs and a controller adapted to control a flow of current to said plural outputs, said controller including a soft-start circuit used to inhibit said flow of current during start-up of said power converter, a method for protecting said power converter from an over-current or short circuit condition comprises the steps of:
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detecting a change in voltage of any one of said plural outputs;
activating said soft-start circuit upon detection of said voltage change; and
after a predetermined period of time, resuming normal operation of said power converter. - View Dependent Claims (10, 11, 12)
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13. A switching mode power converter, comprising:
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an inductor coupled to a rectification stage having a plurality of outputs;
a switch connected in series with said inductor;
an input voltage source coupled to said inductor;
a controller adapted to control operation of said switch to control a flow of current through said inductor, said controller including a feedback circuit to determine a duty cycle of said switch in response to a detected voltage of at least one of said plurality of outputs and a detected current through said inductor, said controller further including a soft-start circuit used to inhibit activation of said switch for a predetermined period of time; and
an over-current protection circuit coupled to said plurality of outputs so as to detect a change in a voltage of any one of said outputs due to a load over-current or short circuit condition, wherein upon detection of said voltage change, said over-current protection circuit activates said soft-start circuit to shut off delivery of said flow of current through said inductor for said predetermined period of time. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification