TWI845423B - Charger and its control circuit - Google Patents

Abstract

A charger and a control circuit thereof are provided. The control circuit used in the charger is configured to: detect whether the charging male interface is about to be disconnected from the device to be charged when the charging male interface is connected to the device to be charged via the charging female interface; and when the charging male interface is about to be disconnected from the device to be charged, reduce the charging voltage provided by the charger at the charging pin of the charging male interface. According to the control circuit used in the charger of the embodiment of the present invention, arcing can be prevented between the charging male interface and the charging female interface when the interface is hot-plugged, thereby preventing the connection components of the charging male interface and the charging female interface from melting or burning when the interface is hot-plugged.

Description

Charger and its control circuit

The present invention relates to the field of circuits, and more specifically to a charger and its control circuit.

In recent years, with the improvement of electronic equipment performance and the update of battery technology, low-power charging can no longer meet the power requirements of electronic equipment. At present, the maximum output of the Universal Serial Bus Type-C (USB Type-C) interface has been increased to 48V/5A, which brings great challenges to the USB Type-C interface. Specifically, because the impedance of the connecting components of the USB Type-C interface gradually increases with the increase of its exposure to the air time and the increase of the number of times the interface is plugged and unplugged, the increase in the impedance of the connecting components will cause the USB Type-C interface to generate arcs during hot plugging. Under the condition of 240W load, the arc may cause the connecting components of the USB Type-C interface to melt or even burn.

According to the control circuit used in the charger according to the embodiment of the present invention, when the charging male interface is connected to the device to be charged via the charging female interface, it is configured to: detect whether the charging male interface is about to be disconnected from the device to be charged; and when the charging male interface is about to be disconnected from the device to be charged, reduce the charging voltage provided by the charger at the charging pin of the charging male interface.

According to the control circuit used in the charger according to the embodiment of the present invention, arcing can be prevented between the charging male interface and the charging female interface when the interface is hot-plugged, thereby preventing the connection components of the charging male interface and the charging female interface from melting or burning when the interface is hot-plugged.

200: Control circuit

202: Switch drive module

204: Internal discharge module

206: Unplug the detection module

208:Logic control module

CC1, CC2, VBUS: Type-C pins

CC1/CC2: Identification detection

comp: comparator

DC: Direct current power supply

Gate driver: driving voltage

GND: ground pin

IC_CC1, IC_CC2: chip pins

IC_DET: detection terminal

IC_GATE: MOSFET driver

IC_VBUS: VBUS discharge

IC_VDD: chip power supply voltage

Idet: Fixed current source

Q1,Q2: Transistor

Rd: resistance

t1,t2,t3,t4: time

Td: Threshold time

VBUS dis: output discharge current

Vth: first voltage threshold

The present invention can be better understood from the following description of the specific implementation of the present invention in conjunction with the drawings, wherein:

Figure 1 shows a schematic diagram of a charging male plug interface according to an embodiment of the present invention.

FIG2 shows a block diagram of a control circuit used in a charger according to an embodiment of the present invention.

FIG3 shows a circuit diagram of the unplugging detection module shown in FIG2.

Figure 4 shows the working waveforms related to each functional module shown in Figure 2.

The features and exemplary embodiments of various aspects of the present invention are described in detail below. In the detailed description below, many specific details are set forth in order to provide a comprehensive understanding of the present invention. However, it is obvious to a person skilled in the art that the present invention can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific configuration and algorithm set forth below, but covers any modification, substitution and improvement of elements, components and algorithms without departing from the spirit of the present invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessary ambiguity of the present invention.

In view of the challenges faced by the USB Type-C interface when its maximum output is increased to 48V/5A, a control circuit for use in a charger according to an embodiment of the present invention is proposed, which can detect whether the charging male interface is about to be disconnected from the device to be charged when the charging male interface is connected to the device to be charged via the charging female interface, and reduce the charging voltage provided by the charger at the charging pins of the charging male interface when the charging male interface is about to be disconnected from the device to be charged. By reducing the charging voltage provided by the charger at the charging pins of the charging male interface when the charging male interface is disconnected from the device to be charged, arcing can be prevented when the charging male interface and the charging female interface are hot-plugged, thereby preventing the connection parts of the charging male interface and the charging female interface from melting or burning when the interface is hot-plugged.

In some embodiments, a conductive sheet may be provided on the outer shell of the male charging interface and connected to the detection terminal of the control circuit used in the charger according to the embodiment of the present invention. The control circuit used in the charger according to the embodiment of the present invention may be configured to detect whether the male charging interface will be disconnected from the device to be charged in the following manner: providing a fixed current to the detection terminal, detecting whether the voltage at the detection terminal is less than a first voltage threshold, and determining that the male charging interface will be disconnected from the device to be charged when the voltage at the detection terminal is less than the first voltage threshold. Specifically, when the operator disconnects the charging male interface from the device to be charged, he usually touches the conductive sheet on the outer shell of the charging male interface. Due to the equivalent impedance of the human body, this will cause the resistance value between the detection terminal and the ground to decrease. Therefore, it is possible to detect whether the charging male interface will be disconnected from the device to be charged by providing a fixed current to the detection terminal and detecting the voltage change at the detection terminal.

In some embodiments, when the operator disconnects the charging male interface from the device to be charged, the operator usually contacts the conductive sheet on the outer shell of the charging male interface continuously rather than briefly. Therefore, the control circuit used in the charger according to the embodiment of the present invention can also be configured to determine that the charging male interface will be disconnected from the device to be charged when the voltage at the detection terminal is less than the first voltage threshold for a threshold time. This can avoid the operator accidentally touching the conductive sheet on the outer shell of the charging male interface and affecting the charging of the device to be charged by the charger.

In some embodiments, the control circuit used in the charger according to the embodiment of the present invention can reduce the charging voltage provided by the charger at the charging pin of the charging male interface by: disconnecting the connection between the output terminal of the switching power circuit in the charger and the charging pin of the charging male interface, and providing a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface. Here, the second voltage threshold can be related to the output voltage at the output terminal of the switching power circuit in the charger, or it can be a predetermined voltage threshold independent of the output voltage at the output terminal of the switching power circuit in the charger.

FIG1 shows a schematic diagram of a charging male interface according to an embodiment of the present invention. It should be understood that although FIG1 only shows a conductive sheet on one side of the outer shell of the charging male interface, in actual application, one or more conductive sheets may be provided on one or more sides of the outer shell of the charging male interface.

FIG2 shows a block diagram of a control circuit used in a charger according to an embodiment of the present invention. As shown in FIG2, the control circuit 200 used in a charger according to an embodiment of the present invention includes a switch drive module 202, an internal discharge module 204, a pull-out detection module 206, and a logic control module 208, wherein: the switch drive module 202 is configured to drive the output terminal of the switch power circuit in the charger to connect to the charging male interface (e.g., USB The internal discharge module 204 is configured to provide a charging voltage not higher than a second voltage threshold at the charging pin of the charging male interface; the removal detection module 206 is configured to detect whether the voltage at the detection terminal (e.g., detection terminal IC_DET) of the control circuit 200 is less than the first voltage threshold. value; the logic control module 208 is configured to control the switch drive module 202 to switch the transistor between the output terminal of the switch power circuit in the charger and the charging pin of the charging male interface from the on state to the off state when the voltage at the detection terminal of the control circuit 200 is less than the first voltage threshold, and at the same time control the internal discharge module 204 to provide a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface.

It should be understood that in the control circuit 200 according to the embodiment of the present invention, the switch drive module 202 can be configured to control various transistors (for example, N-type or P-type metal oxide semiconductor field effect transistor (N-type Metal-Oxide-Semiconductor Field-Effect Transistor, N-MOSFET) or (P-type Metal-Oxide-Semiconductor Field-Effect Transistor, Transistor, P-MOSFET), back-to-back MOSFET, etc.) are turned on and off; the internal discharge module 204 can be configured to provide a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface through one or more of constant voltage discharge, constant current discharge, and constant impedance discharge, wherein the discharge of the internal discharge module 204 can be controlled by a transistor (for example, transistor Q2) located inside or outside the control circuit 200; the unplug detection module 206 can be configured to detect whether the voltage at the detection terminal of the control circuit 200 is less than the first voltage threshold through one or more of high and low level detection, current detection, and impedance detection.

Fig. 3 shows a circuit diagram of the unplugging detection module shown in Fig. 2. As shown in Fig. 3, the unplugging detection module 206 includes a fixed current source Idet and a comparator comp, wherein: the fixed current source Idet is configured to provide a fixed current to the detection terminal IC_DET; the comparator comp is configured to compare whether the voltage at the detection terminal IC_DET is less than the first voltage threshold Vth. Specifically, the unplugging detection module 206 can be powered by the chip power supply voltage IC_VDD of the control circuit 200. The fixed current source Idet flows a weak current to the resistor Rd through the detection terminal IC_DET when the control circuit 200 is powered on. The comparator comp outputs a high-level comparison result signal when it detects that the voltage at the detection terminal IC_DET is lower than the first voltage threshold Vth (correspondingly, it outputs a low-level comparison result signal when it detects that the voltage at the detection terminal IC_DET is not lower than the first voltage threshold Vth). In Figure 3, if the operator is disconnecting the charging male interface from the device to be charged, Rd represents the resistance generated by the conductive sheet on the outer shell of the charging male interface in parallel with the equivalent resistance of the human body. Otherwise, Rd represents the resistance of the conductive sheet on the outer shell of the charging male interface.

FIG4 shows the working waveforms related to the functional modules shown in FIG2 , wherein: VBUS represents the voltage at the charging pin of the charging male interface, Gate driver represents the driving voltage of the switch driving module 202, VBUS dis represents the output discharge current of the internal discharge module 204, and IC_DET represents the voltage at the detection terminal IC_DET. Combining Figures 2 to 4, it can be seen that from 0 to t1, the charger is not connected to the device to be charged, and the voltage at the detection terminal IC_DET is IC_VDD; at t1, the operator is about to connect the charging male interface to the device to be charged and thus touches the conductive sheet on the outer shell of the charging male interface. Due to the equivalent impedance of the human body, the voltage at the detection terminal IC_DET is pulled down to below the first voltage threshold Vth, and the comparator Comp output is The signal level flips, but since the charger is not connected to the device to be charged at this time, the transistor Q1 is still in the disconnected state, and the control circuit 200 does not need to do any relevant processing; at t2, the operator connects the charging male interface to the device to be charged; at t3, the operator disconnects the conductive sheet on the outer shell of the charging male interface, and the transistor Q1 changes from the off state to the on state, and the charger starts to charge the device to be charged normally; at t4, the operator The charging male connector is unplugged from the device to be charged, and thus continues to contact the conductive sheet on the outer shell of the charging male connector. The voltage at the detection terminal IC_DET is pulled down to be lower than the first voltage threshold Vth and lasts for the threshold time Td. The signal output by the comparator Comp reverses in level. The logic control module 208 detects that the charging male connector is about to be disconnected from the device to be charged, and immediately controls the switch drive module 202 to change the transistor Q1 from the on state to the off state. The circuit is switched off to cut off the path between the output terminal of the switch power circuit in the charger and the charging pin of the charging male interface, and the internal discharge module 204 is simultaneously activated to provide a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface, so that when the charging male interface is unplugged from the charging female interface, the voltage at the charging pin has been reduced to a lower voltage or even 0V, which can effectively alleviate the arc aging problem of the charging male interface and the charging female interface.

The present invention may be implemented in other specific forms without departing from its spirit and essential features. For example, the algorithm described in a specific embodiment may be modified, and the system architecture does not deviate from the basic spirit of the present invention. Therefore, the present embodiments are considered to be exemplary rather than restrictive in all aspects, the scope of the present invention is defined by the attached claims rather than the above description, and all changes that fall within the meaning and scope of equivalents of the claims are therefore included in the scope of the present invention.

200: Control circuit

202: Switch drive module

204: Internal discharge module

206: Unplug the detection module

208:Logic control module

CC1/CC2: Identification detection

CC1, CC2, VBUS: Type-C pins

DC: Direct current power supply

GND: ground pin

IC_CC1, IC_CC2: chip pins

IC_DET: detection terminal

IC_GATE: MOSFET driver

IC_VBUS: VBUS discharge

IC_VDD: chip power supply voltage

Q1,Q2: Transistor

Claims (9)

A control circuit used in a charger is configured to: detect whether the charging male interface is about to be disconnected from the device to be charged when the charging male interface is connected to the device to be charged via the charging female interface; when the charging male interface is about to be disconnected from the device to be charged, reduce the charging voltage provided by the charger at the charging pin of the charging male interface; and provide a switch drive module, which is configured to drive the transistor between the output terminal of the switching power supply circuit in the charger and the charging pin of the charging male interface to be turned on and off; An internal discharge module is configured to provide a charging voltage not higher than a second voltage threshold at the charging pin of the charging male interface; and a logic control module is configured to control the switch drive module to switch the transistor between the output terminal of the switching power supply circuit in the charger and the charging pin of the charging male interface from the on state to the off state when the voltage at the detection terminal is less than the first voltage threshold, and at the same time control the internal discharge module to provide a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface. A control circuit as described in claim 1, wherein the control circuit has a detection terminal connected to a conductive sheet on the outer shell of the charging male interface, and the control circuit is also configured to detect whether the charging male interface will be disconnected from the device to be charged by the following processing: providing a fixed current to the detection terminal; detecting whether the voltage at the detection terminal is less than a first voltage threshold; and when the voltage at the detection terminal is less than the first voltage threshold, determining that the charging male interface will be disconnected from the device to be charged. The control circuit as described in claim 2, wherein the control circuit is further configured to: when the voltage at the detection terminal is less than the first voltage threshold for a threshold time, determine that the charging male interface will be disconnected from the device to be charged. A control circuit as described in claim 2 or 3, wherein the control circuit is further configured to reduce the charging voltage provided by the charger at the charging pin of the charging male interface by the following processing: disconnecting the connection between the output terminal of the switching power circuit in the charger and the charging pin of the charging male interface, and providing a charging voltage not higher than the second voltage threshold at the charging pin of the charging male interface. A control circuit as described in claim 2, wherein the control circuit comprises: a fixed current source configured to provide a current of a fixed magnitude to the detection terminal; and a comparator configured to compare whether the voltage at the detection terminal is less than the first voltage threshold. A control circuit as described in claim 4, wherein the second voltage threshold is related to the output voltage at the output terminal of the switching power supply circuit in the charger or is a predetermined voltage threshold independent of the output voltage at the output terminal of the switching power supply circuit in the charger. A control circuit as described in claim 2, wherein the conductive sheet on the outer shell of the charging male interface includes one or more conductive sheets respectively located on one or more sides of the outer shell of the charging male interface. A control circuit as described in claim 1, wherein the charging male interface is a Universal Serial Bus Type-C (USB Type-C) male interface. A charger comprising a control circuit as described in any one of claims 1 to 8.

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