Integrated power supply protection circuit
AssigneeInnoveta Technologies
InventorsRaul Alcantar, Carl Milton Wildrick
Life of this patent
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Abstract
A power supply with a protection circuit that protects against over current, short circuit, output overvoltage, and input undervoltage with a minimal number of components. A pulse width modulated power supply has a controller using two operational amplifiers, namely an error amplifier and an overvoltage comparator, which are used to limit the duty cycle of the power supply. When the output voltage differs significantly from a reference, the overvoltage comparator triggers causing the supply to enter hiccup mode wherein it shuts off and automatically restarts, checking to see if the condition which caused shutdown is still present.
Claims12
A pulse width modulated power supply system, comprising:
- a controller having an integrated overvoltage detection function connected to sense an output of an error amplifier;
- wherein if the output of the error amplifier differs from a reference voltage, the power supply enters a hiccup mode.
A switching power supply protection system, comprising:
- a controller having an overvoltage detection function;
- wherein, when the switching power supply experiences input undervoltage conditions, output overvoltage conditions, short circuit conditions, or overload conditions, the overvoltage detection function causes the switching power supply to at least temporarily stop switching;
- and
- wherein a soft start capacitor discharges, thereby decreasing a duty cycle, responsive to the overvoltage detection function.
A switching power supply circuit having an output, comprising:
- a first operational amplifier having a first reference voltage as input and a first voltage as input, the first voltage being proportional to an output of the power supply;
- a comparator having a second reference voltage as input and a second voltage as input, the second voltage being proportional to an output of the operational amplifier;
- wherein an output of the comparator controls discharge of a soft start capacitor, the soft start capacitor allowing a duty cycle of the power supply to increase or decrease;
- wherein when the duty cycle of the power supply increases above a threshold due to an input undervoltage condition or output overvoltage condition, the output of the operational amplifier increases such that the comparator saturates;
- wherein when the operational amplifier saturates because of a short circuit condition or an overload condition, the comparator saturates;
- and
- wherein when the comparator saturates, the output of the switching power supply at least temporarily stops switching and enters a hiccup mode wherein the switching power supply stops switching briefly, then restarts.
A method of protecting a switching power supply, comprising the steps of:
- inputting a first voltage to an operational amplifier, the first voltage being proportional to an output voltage of the power supply;
- inputting a first reference voltage to the operational amplifier;
- inputting a second voltage to a comparator, the second voltage being proportional to an output of the operational amplifier;
- inputting a second reference voltage to the comparator;
- wherein when a duty cycle of the power supply increases as a soft start capacitor charges, the duty cycle increasing above a threshold due to an input undervoltage condition or output overvoltage condition, the output of the operational amplifier increases such that the comparator saturates;
- wherein when the operational amplifier saturates because of a short circuit condition or an overload condition, the comparator saturates;
- and
- wherein when the comparator saturates, the output of the switching power supply at least temporarily stops switching and enters a hiccup mode wherein the power supply shuts down briefly, then restarts.
Dependencies are inferred from the claim text.