1. A method of forming a power overload detection circuit of a switching power supply system comprising:
configuring the power overload detection circuit to use a reference signal derived from a bulk voltage wherein the bulk voltage is used to form an output voltage of the switching power supply system;
configuring the switching power supply system to receive a feedback signal that is representative of the output voltage and to use the feedback signal to regulate a value of the output voltage; and
configuring the power overload detection circuit to compare the feedback signal to the reference signal and set an operating state of the switching power supply system.
2. The method of claim 1 wherein configuring the power overload detection circuit to compare the feedback signal to the reference signal and set an operating state of the switching power supply system includes configuring the power overload detection circuit to set the operating state responsively to detecting a power overload condition.
3. The method of claim 1 wherein configuring the power overload detection circuit to use the reference signal derived from the bulk voltage includes configuring the power overload detection circuit to form a reference signal that varies inversely proportional to variations in the bulk voltage.
4. The method of claim 1 wherein configuring the power overload detection circuit to use the reference signal derived from the bulk voltage includes configuring a transconductance amplifier to receive the reference signal and responsively form an amplified reference signal that varies inversely proportional to the reference signal.
5. The method of claim 4 wherein configuring the transconductance amplifier to receive the reference signal and responsively form the amplified reference signal that varies inversely proportional to the reference signal includes configuring a comparator to compare the feedback signal to the amplified reference signal.
6. The method of claim 1 wherein configuring the power overload detection circuit to use the reference signal derived from the bulk voltage includes coupling a single amplifier to form the reference signal that varies inversely proportional to variations in the bulk voltage.
7. The method of claim 6 wherein coupling the single amplifier to form the reference signal that varies inversely proportional to variations in the bulk voltage includes coupling a differential coupled transistor pair to receive a signal representative of the bulk voltage and to receive a fixed reference signal, and also includes coupling the transistor pair to a current mirror.
8. The method of claim 6 wherein coupling the transistor pair to the current mirror includes configuring a resistor divider to form a voltage that is proportional to the bulk voltage, coupling the transistor pair to receive the voltage that is proportional to the bulk voltage and responsively form a mirror current through the current mirror.
9. The method of claim 1 wherein configuring the power overload detection circuit to use the reference signal derived from the bulk voltage includes configuring a transconductance amplifier to receive the feedback signal and responsively form an amplified reference signal that varies inversely proportional to the feedback signal.
10. A method of forming a skip cycle comparator of a power supply system comprising:
configuring the skip cycle comparator to receive a reference signal derived from a bulk voltage used to form an output voltage of the power supply system;
configuring a switching power supply controller of the power supply system to receive a feedback signal that is representative of the output voltage and to use the feedback signal to regulate a value of the output voltage; and
configuring the skip cycle comparator to compare the feedback signal to the reference signal and responsively set an operating state of the switching power supply controller.
11. The method of claim 10 wherein configuring the skip cycle comparator to compare the feedback signal to the reference signal and responsively set the operating state of the switching power supply controller includes configuring the skip cycle comparator to set the operating state to a skip cycle mode responsively to the feedback signal being less than a first value.
12. The method of claim 10 wherein configuring the skip cycle comparator to receive a reference signal derived from a bulk voltage includes coupling a resistor divider to form a reference voltage that is proportional to the bulk voltage.
13. The method of claim 12 wherein configuring the skip cycle comparator to compare the feedback signal to the reference signal includes coupling the skip cycle comparator to compare the feedback signal to the reference voltage.
14. The method of claim 13 wherein configuring the skip cycle comparator to compare the feedback signal to the reference signal and responsively set the operating state of the switching power supply controller includes coupling an output of the skip cycle comparator to a control circuit that inhibits switching a power switch used to regulate the output voltage.
15. The method of claim 12 wherein coupling the resistor divider to form the reference voltage that is proportional to the bulk voltage includes forming the switching power supply controller on a semiconductor die and forming the resistor divider externally to the semiconductor die.
16. A switching power supply controller configured to form a drive signal operable to control a power switch to use a bulk voltage and form a regulated output voltage comprising:
a skip cycle comparator coupled to receive a first reference signal derived from the bulk voltage and to receive to receive a feedback signal that is representative of the regulated output voltage and responsively set an operating state of the switching power supply controller; and
a power overload detection circuit configured to compare the feedback signal to a second reference signal derived from the bulk voltage and set an operating state of the switching power supply controller responsively to detecting a power overload condition.
17. The switching power supply controller of claim 16 wherein the skip cycle comparator coupled to receive the first reference signal include a resistor divider coupled to receive the bulk voltage and form the first reference signal as a reference voltage that is proportional to the bulk voltage.
18. The switching power supply controller of claim 16 wherein the power overload detection circuit includes differential coupled transistors configured to receive a signal representative of the bulk voltage, a current mirror configured to receive a first current from the differential coupled transistors and form a second current that is inversely proportional to variations in the bulk voltage, and a resistor coupled to convert the second current to a voltage that is inversely proportional to variations in the bulk voltage.
19. The switching power supply controller of claim 16 wherein the power overload detection circuit is operably coupled to form the variable reference current to vary inversely proportional to variations in the bulk voltage.
20. The switching power supply controller of claim 16 wherein the power overload detection circuit includes a transconductance amplifier coupled to receive a reference voltage that is proportional to the bulk voltage and to form an amplified reference voltage that varies inversely proportionally to variations in the bulk voltage.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of rendering video images of a subject at virtual viewpoint in a simulated reality environment, comprising the steps of:
(a) arranging a plurality of video cameras at different views about the subject;
(b) digitally capturing video images of the subject at the different views;
(c) modeling 3D video image of the subject in real-time;
(d) computing virtual images for a viewer at different viewpoints;
(g) incorporating the virtual images into the simulated reality environment in accordance with viewer’s viewpoint.