US-12627219-B2 - Adaptive dead-time control for switching circuitry of a DC converter

US12627219B2US 12627219 B2US12627219 B2US 12627219B2US-12627219-B2

Abstract

Embodiments of a switch converter are disclosed. The switch converter includes switching circuitry with a primary and a secondary switch, an output filter, a high-pass filter, switch control circuitry, and a trigger circuit. The output filter is connected to the switching circuitry. The switch control circuitry controls operation of the primary switch and the secondary switch so that the output filter generates a DC voltage and an enabling signal. The high-pass filter receives a feedback signal and detects a switching event of the switching circuitry with the feedback signal that is generated during a dead time of both the primary switch and the secondary switch are open simultaneously. The transient detector circuit generates a trigger signal in response to the switching event and an enabling signal being in an enabling state. The switching circuitry closes the secondary switch in response to the trigger signal.

Inventors

Masashi Nogawa

Assignees

QORVO US, INC.

Dates

Publication Date: 20260512
Application Date: 20231017

Claims (20)

1 . A switch-mode power converter, comprising: switching circuitry that includes a primary switch and a secondary switch connected in a half-bridge configuration; an output filter connected to the switching circuitry at a node between the primary switch and the secondary switch; a primary switch control circuit configured to control the opening and closing of the primary switch; a secondary switch control circuit configured to control the opening and closing of the secondary switch; a conversion control circuit configured to generate a pulse width modulated (PWM) signal and output the PWM signal to one or more isolators so that the PWM signal becomes an enabling signal once the PWM signal passes through the one or more isolators such that the enabling signal is output to the primary switch control circuit so that the output filter generates a direct current (DC) voltage from the switching circuitry; a high-pass filter coupled to the switching circuitry or the output filter to generate a feedback signal, wherein a switch transient event is provided in the feedback signal in response to the opening of the primary switch; a trigger circuit configured to receive the feedback signal from the high-pass filter and configured to switch a trigger signal from a first signal state to a second signal state in response to the switch transient event, wherein the secondary switch control circuit is configured to close the secondary switch in response to the trigger signal transitioning from the first signal state to the second signal state; and the one or more isolators wherein the one or more isolators isolate the conversion control circuit from the primary switch control circuit and the secondary switch control circuit but do not isolate the high-pass filter from the trigger circuit such that the enabling signal is delayed with respect to the PWM signal due to the one or more isolators but the feedback signal is not delayed by the one or more isolators.
2 . The switch-mode power converter of claim 1 , wherein the primary switch is a high side switch and the secondary switch is a low side switch.
3 . The switch-mode power converter of claim 1 , wherein the primary switch is a low side switch and the secondary switch is a high side switch.
4 . The switch-mode power converter of claim 1 , wherein the trigger circuit comprises a comparator.
5 . The switch-mode power converter of claim 4 , wherein: an inverting terminal of the comparator is configured to receive the feedback signal; a non-inverting terminal of the comparator receives a DC reference voltage having a DC voltage level; and the comparator generates a comparator output in a high voltage state in response to the feedback signal having a first polarity.
6 . The switch-mode power converter of claim 5 , wherein the trigger circuit further comprises an SR latch and wherein: a first input terminal of the SR latch receives the comparator output of the comparator; and a second input terminal of the SR latch receives an enable signal indicative of the PWM signal.
7 . The switch-mode power converter of claim 6 , wherein the trigger circuit further comprises an AND gate, wherein: a first input terminal of the AND gate receives an output of the SR latch; a second input terminal of the AND gate receives the enable signal; and the AND gate is configured to generate the trigger signal.
8 . The switch-mode power converter of claim 1 , wherein the trigger circuit is configured to provide the trigger signal, which is configured to close the secondary switch in response to the trigger signal being in an activation state.
9 . The switch-mode power converter of claim 1 , wherein the one or more isolators comprise a transformer.
10 . The switch-mode power converter of claim 1 , wherein the switch-mode power converter is in a boost configuration.
11 . The switch-mode power converter of claim 1 , wherein the switch-mode power converter is in a buck configuration.
12 . A switching converter, comprising: switching circuitry configured to receive a first direct current (DC) voltage, the switching circuitry including a primary switch and a secondary switch connected in a half-bridge configuration; pass a pulse width modulated (PWM) signal through an isolator to become an enabling signal that is delayed with respect to the PWM signal due to passing through the isolator; a first output filter connected to the switching circuitry, wherein the switching circuitry is configured to open and close the primary switch and the secondary switch in accordance to the enabling signal such that the first output filter generates a second DC voltage from the first DC voltage; a high-pass filter coupled to the switching circuitry or the first output filter to generate a feedback signal, wherein a switch transient event is provided in the feedback signal in response to the opening of the primary switch; a trigger circuit configured to receive the feedback signal from the high-pass filter and configured to switch a trigger signal from a first signal state to a second signal state in response to a switch transient event, wherein the switching circuitry is configured to close the secondary switch in response to the trigger signal transitioning from the first signal state to the second signal state; and wherein no isolators are provided between the trigger circuit and the switching circuitry.
13 . The switching converter of claim 12 , the switching circuitry comprising: the primary switch as a high side switch; and the secondary switch as a low side switch.
14 . The switching converter of claim 12 , the switching circuitry comprising: the primary switch as a low side switch; and the secondary switch as a high side switch.
15 . The switching converter of claim 12 , wherein the trigger circuit comprises a comparator.
16 . The switching converter of claim 15 , wherein: an inverting terminal of the comparator is configured to receive the feedback signal; a non-inverting terminal of the comparator receives a DC reference voltage having a DC voltage level; and the comparator generates a comparator output in a high voltage state in response to the feedback signal having a first polarity.
17 . The switching converter of claim 16 , wherein the trigger circuit further comprises an SR latch and wherein: a first input terminal of the SR latch receives the comparator output of the comparator; and a second input terminal of the SR latch receives an enable signal indicative of the PWM signal.
18 . The switching converter of claim 17 , wherein the trigger circuit further comprises an AND gate, wherein: a first input terminal of the AND gate receives an output of the SR latch; a second input terminal of the AND gate receives the enable signal; and the AND gate is configured to generate the trigger signal.
19 . The switching converter of claim 12 , wherein, in a first mode, the switching converter operates in a boost configuration and in a second mode the switching converter operates in a buck configuration.
20 . A method of operating a switch converter, comprising: generating a direct current (DC) voltage using an output filter and switching circuitry, the switching circuitry comprising a primary switch and a secondary switch; delaying a pulse width modulation (PWM) signal with an isolator so that the PWM signal becomes an enabling signal; opening the primary switch in response to an enabling signal being in an enabling state; receiving a feedback signal from the switching circuitry or the output filter, where the feedback signal does not pass through the isolator; detecting a switching transient event in the feedback signal in response to the primary switch being opened while the secondary switch remains open; and closing the secondary switch in response to the switching transient event and the enabling signal being in the enabling state.

Description

RELATED APPLICATIONS This application claims the benefit of provisional patent application Ser. No. 63/385,332, filed Nov. 29, 2022, the disclosure of which is hereby incorporated herein by reference in its entirety. BACKGROUND Switch converters are used to efficiently convert a DC input voltage at a first voltage level to a DC output voltage at a second voltage level. The switch converter does this by opening and closing a primary and a secondary switch and filtering the output of the switch converter with an output filter (usually an LC filter). To prevent the switch converter from causing a short circuit, the primary switch and the secondary switch should not be closed simultaneously. Thus, during any switch cycle, the primary switch and the secondary switch are both opened before closing the primary switch and opening the secondary switch or before opening the primary switch and closing the secondary switch. However, when both the primary switch and the secondary switch are both opened, the secondary switch operates a diode mode (using the body diode of the secondary switch). At high power levels, the current that flows through the body diode of the secondary switch consumes power and therefore creates inefficiencies. SUMMARY Embodiments of a switch converter are disclosed. In some embodiments, the switch converter includes switching circuitry, an output filter, a high-pass filter, switch control circuitry, and a trigger circuit. The switching circuitry includes a primary switch and a secondary switch connected in a half-bridge configuration. The output filter is connected to the switching circuitry. The switch control circuitry configured to control the opening and closing of the primary switch and the secondary switch so that the output filter generates a direct current (DC) voltage and generate an enabling signal in an enabling state in response to the primary switch being opened. The high-pass filter is configured to receive a feedback signal, wherein the high-pass filter is configured to filter out a switching transient edge in the feedback signal that is generated in response to the primary switch being open while the secondary switch stays open. The trigger circuit is configured to generate a trigger signal in an activation state in response to the transient edge and the enabling signal being in the enabling state. The switching circuitry is configured to close the secondary switch in response to the trigger signal being in the activation state. In another aspect, any of the foregoing aspects individually or together, and/or various separate aspects and features as described herein, may be combined for additional advantage. Any of the various features and elements as disclosed herein may be combined with one or more other disclosed features and elements unless indicated to the contrary herein. Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. BRIEF DESCRIPTION OF THE DRAWING FIGURES The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure. FIG. 1A is a block diagram of a switch converter, in accordance with some embodiments. FIG. 1B and FIG. 1C are simplified block diagrams of the driver circuit, the switch, and the switch of FIG. 1A in the boost configuration, in accordance with some embodiments. FIG. 1D is a signal diagram for the trigger circuit in FIG. 1B, in accordance with some embodiments. FIG. 1E is a signal diagram for the trigger circuit in FIG. 1C, in accordance with some embodiments. FIG. 2 illustrates voltage waveforms that demonstrate the operation of a high-pass filter and a trigger circuit, in accordance with some embodiments. FIG. 3 is a flow diagram illustrating a method of operating a switch converter, in accordance with some embodiments. DETAILED DESCRIPTION The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a