Discontinuous conduction mode (DCM) using sensed current for a switch-mode converter
First Claim
1. A switching converter controller for controlling a switch-mode converter which has a switch and an inductor coupled to the switch wherein the switch-mode converter receives an input voltage and provides an output voltage and wherein a sensed current is observed from the switch-mode converter, comprising:
- a comparator for receiving and comparing a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current, wherein further the multiplying factor is greater than or equal to two; and
a finite state machine, configured to operate the switch-mode converter in a discontinuous conduction mode (DCM), responsive to comparisons made by the comparator, for;
turning on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current;
calculating a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and
varying the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current.
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Abstract
A switch-mode converter controller and method utilizes a comparator for receiving and comparing a sensed current and a peak current that is determined by a product of a multiplying factor, that is greater than or equal to two, and a target current. A finite state machine (FSM) is configured to operate the switch-mode converter in a discontinuous conduction mode (DCM). Responsive to the comparator, the FSM turns on the switch and observes an on-time duration of the switch until the sensed current reaches the peak current; calculates a switching period responsive to the peak current and the observed on-time duration; and varies the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. The FSM can also be configured to alternatively operate the switch-mode converter in a continuous conduction mode (CCM).
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Citations
35 Claims
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1. A switching converter controller for controlling a switch-mode converter which has a switch and an inductor coupled to the switch wherein the switch-mode converter receives an input voltage and provides an output voltage and wherein a sensed current is observed from the switch-mode converter, comprising:
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a comparator for receiving and comparing a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current, wherein further the multiplying factor is greater than or equal to two; and a finite state machine, configured to operate the switch-mode converter in a discontinuous conduction mode (DCM), responsive to comparisons made by the comparator, for; turning on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current; calculating a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and varying the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for controlling a switch-mode converter which has a switch and an inductor coupled to the switch wherein the switch-mode converter receives an input voltage and provides an output voltage and wherein a sensed current is observed from the switch-mode converter, comprising:
in configuring to operate the switch-mode converter in a discontinuous conduction mode (DCM) and responsive to comparisons made by the comparing; comparing a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current wherein further the multiplying factor is greater than or equal to two; turning on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current; calculating a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and varying the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A power factor corrector (PFC), comprising:
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a switch-mode boost stage having a switch and an inductor coupled to the switch wherein the switch-mode boost stage receives a rectified line input voltage and provides a link output voltage and wherein a sensed current is observed from the switch-mode boost stage; a target current generator for receiving the link output voltage and for generating a target current proportionate to the rectified line input voltage; a comparator for receiving and comparing a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current, wherein further the multiplying factor is greater than or equal to two; and a finite state machine, configured to operate the switch-mode converter in a discontinuous conduction mode (DCM), responsive to comparisons made by the comparator, for; turning on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current; calculating a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and varying the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for power factor correction (PFC), comprising:
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coupling a switch and an inductor together to form a switch-mode boost stage that receives a rectified line input voltage and provides a link output voltage; observing a sensed current from the switch-mode boost stage; receiving the link output voltage; generating a target current proportionate to the rectified line input voltage; and in configuring to operate the switch-mode converter in a discontinuous conduction mode (DCM) and responsive to comparisons made by the comparing; comparing a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current wherein further the multiplying factor is greater than or equal to two; turning on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current; calculating a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and varying the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. - View Dependent Claims (26, 27, 28, 29, 30, 31)
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32. An integrated circuit which incorporates a switch-mode converter controller for controlling a switch-mode converter which has a switch and an inductor coupled to the switch wherein the switch-mode converter receives an input voltage and provides an output voltage and wherein a sensed current is observed from the switch-mode converter, and wherein the switch-mode converter controller includes a comparator and a finite state machine, the integrated circuit configured to:
in configuring to operate the switch-mode converter in a discontinuous conduction mode (DCM) and responsive to comparisons made by the comparing; compare a sensed current value representative of the sensed current and a peak current value representative of a peak current, wherein the peak current is determined by a product of a multiplying factor and a target current wherein further the multiplying factor is greater than or equal to two; turn on the switch and observing an on-time duration of the switch until the sensed current reaches the peak current; calculate a switching period of a switch control signal for controlling the switch wherein the switching period is responsive to the peak current and the observed on-time duration; and vary the switching period responsive to the on-time duration and the multiplying factor such that an average of the sensed current equals the target current. - View Dependent Claims (33, 34, 35)
Specification