# US 2021/0344267 A1 · Communicating fault indications between primary and secondary controllers in a secondary-controlled flyback converter

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- Number: US 2021/0344267 A1
- Document ID: US20210344267A1
- Status: Published application
- Kind: A1
- Application number: 17/197,309
- Filed: 2021-03-10
- Published: 2021-11-04
- Earliest claimed: 2019-06-27
- Assignees: Cypress Semiconductor Corporation
- Applicants: Cypress Semiconductor Corporation
- Inventors: Arun Khamesra; Hariom Rai; Pulkit Shah
- Web page: https://patentgrep.com/patent/US20210344267A1

## CPC

- H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop}
- H02M 1/32: Means for protecting converters other than automatic disconnection
- H02M 3/33592: {having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer}
- H02H 1/0061: {concerning transmission of signals (transmission of measured quantities or switching orders; sectionalised protection involving signal transmission between at least two stations H02H7/261; comparison of the voltage or current values at two spaced portions of a single system H02H3/28; transferring the output of a sensing member to another variable G01D5/00; electrical measuring arrangements using modulation of electromagnetic waves, e.g. light beams G01R15/24, G01R15/26)}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- 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)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

Communicating fault conditions between primary-side and secondary-side controllers of a Universal Serial Bus Power Delivery (USB-PD) device is described. The primary-side controller receives a control signal from the secondary-side controller across a galvanic isolation barrier. The primary-side controller converts the control signal into a first pulse signal and applies the first pulse signal to control a primary-side switch. When the primary-side controller detects that a first fault condition has occurred, the primary-side controller communicates a first information signal about the first fault condition to the secondary-side controller across the galvanic isolation barrier. The first information signal is generated by converting the control signal into a second pulse signal having a different pulse width than the first pulse signal. The primary-side controller applies the second pulse signal to control the primary-side power switch.

## Claims

### Claim at position 1

1-20. (canceled)

### Claim 21

A method comprising:
receiving, by a primary-side controller of a Universal Serial Bus Power Delivery (USB-PD) device from a secondary-side controller of the USB-PD device, a control signal across a galvanic isolation barrier;
converting, by the primary-side controller, the control signal into a first pulse signal with a first pulse width;
applying, by the primary-side controller, the first pulse signal to a primary-side power switch to control the primary-side power switch;
detecting, by the primary-side controller, that a first fault condition has occurred;
communicating, by the primary-side controller, a first information signal about the first fault condition to the secondary-side controller across the galvanic isolation barrier, wherein the first information signal is generated by converting the control signal into a second pulse signal with a second pulse width that is different than the first pulse width; and
applying the second pulse signal to the primary-side power switch to control the primary-side power switch.

### Claim 22 (depends on 21)

The method of claim 21, wherein receiving the control signal from the secondary-side controller comprises receiving the control signal across the galvanic isolation barrier via a pulse transformer coupled between the primary-side controller and the secondary-side controller.

### Claim 23 (depends on 21)

The method of claim 21, wherein converting the control signal into the first pulse signal and converting the control signal into the second pulse signal comprises using a pulse receiver of the primary-side controller to generate the first pulse signal with the first pulse width and to generate the second pulse signal with the second pulse width.

### Claim 24 (depends on 23)

The method of claim 23, wherein using the pulse receiver of the primary-side controller further comprises one or more of:
generating first one or more additional pulses with the first pulse width to vary the first pulse signal; and
generating second one or more additional pulses with the second pulse width to vary the second pulse signal.

### Claim 25 (depends on 21)

The method of claim 21, further comprising:
detecting, by the secondary-side controller, that a second fault condition has occurred; and
communicating, by the secondary-side controller, a second information signal about the second fault condition to the primary-side controller across the galvanic isolation barrier by varying a pulse sequence of the control signal received by the primary-side controller.

### Claim 26 (depends on 25)

The method of claim 25, wherein varying the pulse sequence of the control signal comprises generating the pulse sequence to include a specific pattern of ones and zeros that corresponds to the second fault condition.

### Claim 27 (depends on 25)

The method of claim 25, wherein the specific pattern of ones and zeros includes one of a start pattern, a stop pattern, a first soft-fault pattern requesting a soft-start operation, and a second soft-fault pattern requesting a minimum delivery of power.

### Claim 28 (depends on 25)

The method of claim 25, further comprising:
determining, by the secondary-side controller, that the second fault condition requires a system shutdown; and
initiating, by the primary-side controller, a shutdown of the USB-PD device in response to receiving the second information signal.

### Claim 29 (depends on 21)

The method of claim 21, wherein communicating the first information signal to the secondary-side controller comprises communicating the first information signal from the primary-side controller to the secondary-side controller without clock synchronization of the primary-side controller and the secondary-side controller.

### Claim 30 (depends on 21)

The method of claim 21, wherein communicating the first information signal to the secondary-side controller comprises communicating the first information signal from the primary-side controller to the secondary-side controller without an input buffer and an output buffer disposed between the primary-side controller and the secondary-side controller.

### Claim 31

A Universal Serial Bus Power Delivery (USB-PD) device, the USB-PD device comprising:
a primary-side integrated circuit (IC) controller;
a primary-side power switch coupled to the primary-side IC controller;
a flyback transformer coupled to the primary-side power switch;
a secondary-side power switch coupled to the flyback transformer; and
a secondary-side IC controller coupled to the secondary-side power switch;
wherein the primary-side IC controller is configured to:
receive a control signal from the secondary-side IC controller across a galvanic isolation barrier;
convert the control signal into a first pulse signal with a first pulse width;
apply the first pulse signal to control the primary-side power switch;
detect that a first fault condition has occurred;
communicate a first information signal about the first fault condition to the secondary-side IC controller across the galvanic isolation barrier, wherein the first information signal is generated by converting the control signal into a second pulse signal with a second pulse width that is different than the first pulse width; and
apply the second pulse signal to control the primary-side power switch.

### Claim 32 (depends on 31)

The USB-PD device of claim 31, further comprising a pulse transformer coupled between the primary-side IC controller and the secondary-side IC controller to provide the galvanic isolation barrier, wherein the primary-side IC controller is configured to receive the control signal as one or more pulses via the pulse transformer.

### Claim 33 (depends on 31)

The USB-PD device of claim 31, wherein the primary-side IC controller comprises:
a pulse receiver configured to receive the control signal from the secondary-side IC controller across the galvanic isolation barrier; and
a gate driver coupled to the pulse receiver and to a gate of the primary-side power switch.

### Claim 34 (depends on 33)

The USB-PD device of claim 33, wherein:
the pulse receiver is configured to convert the control signal into the first pulse signal and to convert the control signal into the second pulse signal; and
the primary-side IC controller is configured to provide the first pulse signal and the second pulse signal to the gate driver.

### Claim 35 (depends on 31)

The USB-PD device of claim 31, wherein the primary-side IC controller comprises a fault detection circuit configured to detect multiple types fault conditions that include the first fault condition.

### Claim 36 (depends on 31)

The USB-PD device of claim 31, wherein the secondary-side IC controller is configured to:
detect that a second fault condition has occurred; and
communicate a second information signal about the second fault condition to the primary-side IC controller across the galvanic isolation barrier by varying a pulse sequence of the control signal provided to the primary-side IC controller.

### Claim 37 (depends on 36)

The USB-PD device of claim 36, wherein the secondary-side IC controller comprises a signal generator circuit configured to generate the pulse sequence of the control signal provided to the primary-side IC controller.

### Claim 38 (depends on 31)

The USB-PD device of claim 31, wherein the secondary-side IC controller comprises a negative sensing (NSN) circuit configured to detect the first information signal communicated by the primary-side IC controller.

### Claim 39 (depends on 31)

The USB-PD device of claim 31, wherein the secondary-side IC controller comprises a zero crossing detect (ZCD) circuit configured to detect the first information signal communicated by the primary-side IC controller.

### Claim 40 (depends on 31)

The USB-PD device of claim 31, further comprising:
an alternating current (AC) input terminals;
a rectifier coupled between the AC input terminals and a primary winding of the flyback transformer;
a direct current (DC) output (VBUS) line coupled to a secondary winding of the flyback transformer; and
a USB Type-C port coupled to the VBUS line and to the secondary-side IC controller.