PWM regulator with discontinuous mode and method therefor
First Claim
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1. A method of forming a power supply controller comprising:
- configuring the power supply controller to form a PWM drive signal operable to control a power switch to form a current through an inductor of a power supply system;
configuring the power supply controller to receive a current sense signal that is representative of current flow through the inductor; and
configuring the power supply controller to reduce an operating frequency of the power supply controller responsively to the power supply controller detecting a zero crossing of the current through the inductor and responsively to operating in a discontinuous conduction mode wherein the operating frequency is greater than zero.
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Abstract
In one embodiment, a power supply controller has a variable frequency oscillator that is used for controlling a PWM controller. The power supply controller varies a frequency of the variable frequency oscillator.
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Citations
19 Claims
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1. A method of forming a power supply controller comprising:
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configuring the power supply controller to form a PWM drive signal operable to control a power switch to form a current through an inductor of a power supply system; configuring the power supply controller to receive a current sense signal that is representative of current flow through the inductor; and configuring the power supply controller to reduce an operating frequency of the power supply controller responsively to the power supply controller detecting a zero crossing of the current through the inductor and responsively to operating in a discontinuous conduction mode wherein the operating frequency is greater than zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A power supply control method comprising:
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forming a control signal that is representative of a substantially zero crossing of a current through an energy storage inductor of a power supply system; using the control signal to control a frequency of a clock signal of a variable frequency oscillator wherein the frequency of the clock signal is greater than zero; and applying the clock signal to a PWM controller of the power supply system wherein the PWM controller responsively initiates asserting a PWM drive signal of the power supply system responsively to the clock signal. - View Dependent Claims (10, 11, 12, 13)
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14. A power supply controller comprising:
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a PWM controller coupled to receive a clock signal and responsively generate a PWM drive signal operable to enable a power switch to generate a current through an inductor; and a variable frequency oscillator of the power supply controller configured to generate the clock signal and change an operating frequency of the clock signal responsively to the current through the inductor becoming substantially zero. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification