# US 12,015,349 B2 · Switching circuit, DC/DC converter, and control circuit thereof

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- Number: US 12,015,349 B2
- Document ID: US12015349B2
- Status: Granted
- Kind: B2
- Application number: 18/047,730
- Filed: 2022-10-19
- Published: 2023-04-27
- Granted: 2024-06-18
- Earliest claimed: 2021-10-21
- Assignees: Rohm Co., Ltd.
- Applicants: ROHM Co., LTD.
- Inventors: Shun Fukushima
- Web page: https://patentgrep.com/patent/US12015349B2

## CPC

- H02M 3/1584: {with a plurality of power processing stages connected in parallel}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 3/158: including plural semiconductor devices as final control devices for a single load
- H03K 17/063: {in field-effect transistor switches}
- H03K 17/6871: {the output circuit comprising more than one controlled field-effect transistor}
- H03K 19/00361: {in field effect transistor circuits}
- H03K 19/0175: Coupling arrangements; Interface arrangements (interface arrangements for digital computers G06F3/00, G06F13/00)
- H03K 2217/0081: Power supply means, e.g. to the switch driver
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

Disclosed is a switching circuit including an input terminal, a switching terminal, a grounding terminal, a bootstrap terminal, a high-side transistor connected between the input terminal and the switching terminal, a low-side transistor connected between the switching terminal and the grounding terminal, a bootstrap capacitor connected between the switching terminal and the bootstrap terminal, a bootstrap switch connected between a constant voltage line and the bootstrap terminal, and a driver circuit configured to turn on the bootstrap switch in a period of time in which the low-side transistor is on and to turn off the bootstrap switch in a period of time in which the low-side transistor is off. The bootstrap switch includes two P-channel metal oxide semiconductor transistors connected in anti-series with each other between the constant voltage line and the bootstrap terminal.

## Claims

### Claim 1

A switching circuit comprising:
an input terminal;
a switching terminal;
a grounding terminal;
a bootstrap terminal;
a high-side transistor connected between the input terminal and the switching terminal;
a low-side transistor connected between the switching terminal and the grounding terminal;
a bootstrap capacitor connected between the switching terminal and the bootstrap terminal;
a bootstrap switch connected between a constant voltage line and the bootstrap terminal; and
a driver circuit configured to turn on the bootstrap switch in a period of time in which the low-side transistor is on and to turn off the bootstrap switch in a period of time in which the low-side transistor is off, wherein
the bootstrap switch includes two P-channel metal oxide semiconductor transistors connected in anti-series with each other between the constant voltage line and the bootstrap terminal.

### Claim 2 (depends on 1)

The switching circuit according to claim 1, wherein sources of the two P-channel metal oxide semiconductor transistors are connected to each other.

### Claim 3 (depends on 2)

The switching circuit according to claim 2, wherein the driver circuit includes
a level shifter configured to level-shift a control signal that gives an instruction for turning on or off the bootstrap switch,
a first inverter configured to drive one of the two P-channel metal oxide semiconductor transistors according to output of the level shifter, and
a second inverter configured to drive the other one of the two P-channel metal oxide semiconductor transistors according to the output of the level shifter,
the level shifter level-shifts a high level of the control signal to a voltage of the sources of the two P-channel metal oxide semiconductor transistors and level-shifts a low level of the control signal to a voltage of the switching terminal,
upper-side power supply terminals of the first inverter and the second inverter are connected to the respective sources of the two P-channel metal oxide semiconductor transistors, and
lower-side power supply terminals of the first inverter and the second inverter are connected to the switching terminal.

### Claim 4 (depends on 1)

The switching circuit according to claim 1, wherein drains of the two P-channel metal oxide semiconductor transistors are connected to each other.

### Claim 5 (depends on 4)

The switching circuit according to claim 4, wherein the driver circuit includes
a level shifter configured to level-shift a control signal that gives an instruction for turning on or off the bootstrap switch,
a first inverter configured to drive a first transistor of the two P-channel metal oxide semiconductor transistors that is on a bootstrap terminal side, according to output of the level shifter, and
a second inverter configured to drive a second transistor of the two P-channel metal oxide semiconductor transistors that is on a constant voltage line side, according to the control signal,
the level shifter level-shifts a high level of the control signal to a voltage of the bootstrap terminal and level-shifts a low level of the control signal to a voltage of the switching terminal,
an upper-side power supply terminal of the first inverter is connected to the bootstrap terminal, and a lower-side power supply terminal of the first inverter is connected to the switching terminal, and
an upper-side power supply terminal of the second inverter is connected to the constant voltage line, and a lower-side power supply terminal of the second inverter is grounded.

### Claim 6 (depends on 1)

The switching circuit according to claim 1, wherein the switching circuit is integrally mounted on one semiconductor substrate.

### Claim 7 (depends on 1)

A control circuit of a direct current to direct current converter, the control circuit comprising:
the switching circuit according to claim 1; and
a feedback controller configured to perform feedback control on the switching circuit such that a state of the direct current to direct current converter approaches a target state.

### Claim 8 (depends on 1)

A converter, comprising:
a control circuit, wherein the control circuit comprising the switching circuit according to claim 1, and a feedback controller configured to perform feedback control on the switching circuit such that a state of the converter approaches a target state.