Usb cable with integrated overcurrent and overtemperature protection

Abstract

The invention relates to a cable having a plurality of conductors terminating in a first connector, the first connector including a connection portion having a plurality of pins for facilitating connection to a second connector of opposite gender; a terminal portion including a power terminal providing an electrical connection between a power pin of the connection portion and a power conductor extending through the cable; and a positive temperature coefficient (PTC) chip disposed directly on the power terminal and electrically connected in series between the power terminal and the power conductor.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to the field of circuit protection devices, and more particularly to Universal Serial Bus cables with integrated thermal and overcurrent protection. BACKGROUND

[0002] Universal Serial Bus (USB) cables are increasingly being used to deliver power to electronic devices in addition to their more traditional role of facilitating data communication. With the advent of the recent USB-C standard, USB cables can now deliver up to 100 Watts of power in a relatively small form factor, facilitating high power applications that were previously not possible via USB connections. However, it has been observed that delivering such high power can result in thermal damage to the USB cable, especially in cases where the pins of the USB cable become dirty, bent, or otherwise predisposed to suboptimal connections.

[0003] One technique that has been employed to protect USB cables from overcurrent / overheat is to incorporate a positive temperature coefficient (PTC) element in series with the power carrying conductors of the USB cable, where the PTC element has an increasing resistance as the temperature of the PTC element increases. Thus, when the current flowing through the PTC element increases above a predetermined limit, the PTC element can heat up, which causes the resistance of the PTC element to increase and substantially reduce or halt the current flowing through the USB cable. Damage that would otherwise result from unmitigated fault current flowing through the USB cable is thereby prevented.

[0004] A drawback associated with existing USB cables that incorporate PTC elements for thermal and overcurrent protection is that the response to a fault condition is slow. That is, by the time the PTC element in such a cable is sufficiently heated to cause a substantial reduction in current flowing therethrough, the fault condition (e.g., overheat or overcurrent) can have been allowed to persist in the cable for a long enough time to cause damage to the cable and / or the connected device. Thus, it is desirable to minimize the response time of the PTC element in order to avoid or mitigate damage caused by the fault condition.

[0005] In light of these and other considerations, current improvements can be useful. SUMMARY

[0006] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to determine the scope of the claimed subject matter.

[0007] An exemplary embodiment of a cable according to the present disclosure can include a plurality of conductors terminated in a first connector, the first connector including a connection portion having a plurality of pins for facilitating connection to a second connector of opposite gender; a terminal portion including a power terminal providing an electrical connection between a power pin of the connection portion and a power conductor extending through the cable; and a positive temperature coefficient (PTC) chip disposed directly on the power terminal and electrically connected in series between the power terminal and the power conductor.

[0008] Another exemplary embodiment of a cable according to the present disclosure can include a plurality of conductors terminated in a first connector, the first connector including a connection portion having a plurality of pins for facilitating connection to a second connector of opposite gender; a terminal portion including a power terminal providing an electrical connection between a power pin of the connection portion and a power conductor extending through the cable; a ribbon-type lead connected to and extending from the power terminal; and a positive temperature coefficient (PTC) chip disposed directly on the ribbon-type lead and electrically connected in series between the power terminal and the power conductor. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a perspective view showing an exemplary embodiment of a USB cable having integrated overcurrent protection and overtemperature protection according to the present disclosure;

[0010] Figure 2 is a perspective view showing an exemplary embodiment of a connector of a USB cable according to the present disclosure shown in Figure 1

[0011] Figure 3A is a perspective view showing another exemplary embodiment of a connector of a USB cable according to the present disclosure shown in Figure 1

[0012] Figure 3B is a perspective view showing an exemplary embodiment of a PTC chip and associated connection elements of a connector according to the present disclosure shown in Figure 3A DETAILED DESCRIPTION

[0013] A data / power delivery cable having integrated thermal protection according to the present disclosure will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the cable are presented. The cable may, however, be embodied in many different forms and may be configured to comply with various standards (e.g., IEEE standards), and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey the certain exemplary aspects of the cable to those skilled in the art.

[0014] ​​​Reference is made to Figure 1 , which shows a USB-C data / power delivery cable 10 (hereinafter "cable 10") in accordance with the present disclosure. At first glance, the cable 10 can appear substantially similar to a conventional USB-C cable as would be familiar to one of ordinary skill in the art. The cable 10 can include connectors 12, 14 at opposite ends thereof, as well as rigid plaques 16, 18 adjacent the connectors 12, 14 that provide strain relief in the cable 10 and house interconnections between the connectors 12, 14 and various conductors extending through the cable 10 (to be described in greater detail below).

[0015] Reference is now made to Figure 2 , which shows the connector 12 in isolation from the power conductor 19 of the cable 10 shown connected thereto. It should be understood that the cable 10 can include a plurality of additional conductors (e.g., ground conductors, high-speed data conductors, standard data conductors, etc.), and that such conductors have been omitted from Figure 2 for clarity of the following description. It should also be understood that the connector 14 (see Figure 1 ) of the cable 10 is substantially identical to the connector 12, and thus the following description of the connector 12 will also apply to the connector 14. Figure 2

[0016] The connector 12 can include a connection portion 20 and a terminal portion 22. The connection portion 20 can be adapted to matingly engage with an opposite gender USB-C connector and can house a plurality of electrically conductive pins 23 arranged, for example, in accordance with the USB-C standard. The connector 12 shown is a male USB-C connector, but one of ordinary skill in the art will understand that the improvements of the present disclosure can similarly be implemented in a female USB-C connector.

[0017] The terminal portion 22 of the connector 12 can include a plurality of electrically conductive terminals that are electrically connected to the pins 23 of the connection portion 20 and facilitate electrical connection of the pins 23 to various conductors (e.g., data and power conductors) extending through the cable 10. For example, the terminal portion 22 can include a power terminal 24 (commonly referred to as a "V bus " terminal) to facilitate electrical connection between a power pin ("V bus " pin) 25 of the connection portion 20 and the power conductor 19 of the cable 10. In various embodiments, the power conductor 19 and the power pin 25 can be adapted to handle up to 5 volts at 20 amperes (100 watts). The present disclosure is not limited in this respect.

[0018] Still referring to Figure 2 ​The positive temperature coefficient (PTC) chip 26 can be directly electrically connected in series between the power terminal 24 and the power conductor 19 of the cable 10 to the power terminal 24 of the terminal portion 22 of the connector 12. The PTC chip 26 can be a laminate structure that generally includes a PTC element 28 with electrically conductive pads or electrodes 30 disposed on top and bottom surfaces thereof (the electrode 30 on the bottom surface of the PTC element 28 is not in view, but is substantially identical to the electrode 30 on the top surface of the PTC element 28). The electrodes 30 can be formed of any suitable, electrically conductive material, including but not limited to copper, gold, nickel, tin, etc. The PTC element 28 can be formed of any type of PTC material (e.g., polymeric PTC material, ceramic PTC material, etc.) that is configured to have an electrical resistance that increases with an increase in temperature of the PTC element 28. In particular, the PTC element 28 can have a predetermined "trip temperature" above which the electrical resistance of the PTC element 28 rapidly and substantially increases (e.g., in a non-linear manner) so as to substantially cease current flow therethrough. In the non-limiting, exemplary embodiment of the cable 10, the PTC element 28 can have a trip temperature in the range of 80 degrees Celsius to 130 degrees Celsius.

[0019] In various embodiments, the electrodes 30 on the bottom of the PTC chip 26 can be reflow soldered to the power terminal 24, and the power conductor 19 can be hand soldered to the electrodes 30 on the top surface of the PTC chip 26. The present disclosure is not limited in this regard, and it is contemplated that the electrodes 30 can be electrically connected to the power terminal 24 and the power conductor 19 via any suitable securing means, including but not limited to reflow soldering, hand soldering, laser soldering, spot welding, conductive adhesion, etc.

[0020] During operation of the cable 10, if the temperature of the PTC element 28 increases above its trip temperature, such as can be caused by an overcurrent condition in the cable 10 or by exposure to an external heat source (e.g., the sun, a hot computer chassis, etc.), the PTC element 28 can exhibit a high electrical resistance and can cease or attenuate current flow through the power conductor 19, thereby protecting the cable 10 and connected equipment from damage that can otherwise occur if the current is allowed to continue. Subsequently, when the PTC element 28 cools to a temperature below its trip temperature and again conducts electricity, current can be allowed to flow through the power conductor 19. Thus, the PTC element 28 acts as a resettable fuse that attenuates overheat and overcurrent in the cable 10.

[0021] Advantageously, since the PTC element 28 is implemented on the power terminal 24 of the connector 12 with the entire width of the electrode 30 on the bottom of the PTC chip 26 being soldered, brazed, or otherwise directly connected to the power terminal 24 with no conductors or traces extending therebetween, the thermal coupling between the power terminal 24 and the PTC chip 26 is optimized and the trip time of the PTC element 28 in the event of a fault condition in the connector 12 is minimized. This is in contrast to conventional thermally protected USB cables in which the PTC chip or device is implemented on a printed circuit board (PCB) and connected to the power terminal of the connector by traces and / or flexible conductors. Relative to the embodiments described herein, such cables exhibit poor thermal coupling and thus provide a slower response to a fault condition (i.e., the PTC chip or device warms up and trips slower), which allows over-temperature or over-current conditions to persist for longer periods of time and cause damage to the cable and connected components. Moreover, the arrangement of the connector 12 can be implemented in a smaller form factor relative to conventional thermally protected USB cable connectors.

[0022] Referring now to Figure 3A and 3B , a connector 112 is shown in accordance with an alternative embodiment of the present disclosure. The connector 112 can be substantially similar to the connector 12 described above and can include a PTC chip 126 that is substantially the same as the PTC chip 26 described above. In particular, the PTC chip 126 can include a PTC element 128 having conductive electrodes 130 disposed on its top and bottom surfaces (the electrodes 130 on the bottom surface of the PTC element 128 are not in view but are substantially the same as the electrodes 130 on the top surface of the PTC element 128). The connector 112 can differ from the connector 12 described above in that the PTC chip 126 can be connected to the power terminal 124 of the connector 112 by a ribbon-type lead 131 and can be connected to the power conductor 19 of the cable 10 by a conductive lead pad 132. The term "ribbon-type" is defined herein as being substantially planar and having a cross-sectional area defined by a width that is at least 5 times greater than its thickness, and more preferably, a cross-sectional area defined by a width that is at least 10 times greater than its thickness.

[0023] Referring now to Figure 3BThe strap-type lead 131 can be a substantially planar member (although it can include one or more bends formed therein) that can include an interface portion 134 and a tongue portion 136. The strap-type lead 131 can be formed of any suitable, electrically and thermally conductive material, including but not limited to nickel, copper, silver, gold, tin, etc. The interface portion 134 can be disposed to lie flat against and can be electrically connected to the electrodes 130 on the bottom surface of the PTC element 128. The connection between the interface portion 134 and the electrodes 130 can be achieved via any suitable securing means, including but not limited to reflow soldering, hand soldering, laser soldering, spot welding, conductive adhesion, etc. The interface portion 134 can have a length and a width that are equal to or greater than the length and width of the electrodes 130 on the bottom surface of the PTC element 128 to ensure good electrical and thermal coupling therebetween. In an exemplary embodiment, the interface portion can have a length of about 3.6 millimeters and a width of about 2.8 millimeters. The present disclosure is not limited in this regard.

[0024] The tongue portion 136 of the strap-type lead 131 can extend from the interface portion 134 and can be disposed to lie flat against and can be electrically and thermally coupled to the power terminal 124 of the connector 112. The wide, flat shape of the tongue portion 136 can be particularly well suited to facilitate laser soldering or spot welding to the power terminal 124. The present disclosure is not limited in this regard, and it is contemplated that the tongue portion 136 can be connected to the power terminal 124 using any suitable electrically and thermally conductive securing means, including but not limited to reflow soldering, hand soldering, conductive adhesion, etc.

[0025] The lead pad 132 of the connector 112 can be disposed on the top of the PTC chip 126 to lie flat against and to be electrically connected to the electrodes 130 on the top surface of the PTC element 128. The lead pad 132 can be formed of any suitable, electrically and thermally conductive material, including but not limited to nickel, copper, silver, gold, tin, etc. In a non-limiting embodiment, the lead pad 132 can be reflow soldered to the electrodes 130.

[0026] The lead pads 132 can be relatively thick (e.g., can have a thickness of 0.3 millimeters or greater) to facilitate coupling of the power conductor 19 of the cable 10 to the PTC chip 126 without damaging the PTC chip 126. For example, if the power conductor 19 is directly hand soldered or spot welded to the PTC chip 126, the high heat from the soldering or welding operation can damage the PTC element 128 and / or cause the solder holding the electrode 130 to the PTC element 128 to melt, which causes the electrode 130 to shift relative to the PTC element 128. Thus, the lead pads 132 act as a thermal shield that protects the PTC element 128 and the electrode 130 from damage and shifting during coupling, while facilitating electrical connection between the power conductor 19 and the PTC chip 126. It is contemplated that in various alternative embodiments of the connector 112, the lead pads 132 can be omitted, and the power conductor 19 can be directly connected to the electrode 130 on the top surface of the PTC element 128.

[0027] Advantageously, the ribbon-type lead 131 provides a strong thermal coupling between the power terminal 124 and the PTC chip 126. Thus, the trip time of the PTC element 128 in the event of a fault condition in the connector 112 is minimized. This is in contrast to conventional thermally protected USB cables in which a PTC chip or device is implemented on a printed circuit board (PCB) and connected to the power terminal of the connector by a trace and / or flexible conductor having a relatively small cross-sectional area. Relative to the embodiments described herein, such cables exhibit poor thermal coupling and thus provide a slower response to a fault condition (i.e., the PTC chip or device warms up and trips slower), such that an over-temperature or over-current condition persists for a longer period of time and causes damage to the cable and connected components. Moreover, the arrangement of the connector 112 can be implemented in a smaller form factor relative to conventional thermally protected USB cable connectors.

[0028] It should be appreciated that the connectors 12 and 112 described above can similarly be implemented in power / data transfer cables that comply with standards other than USB-C. For example, the configurations described above can similarly be implemented in cables that comply with the Apple Lightning standard, the Apple Thunderbolt standard, the various generations of Qualcomm Quick Charge standard, and the earlier USB standards. Embodiments of the present disclosure are not limited in this regard.

[0029] As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding additional or further embodiments that can also incorporate such recited features.

[0030] While the present disclosure has been made with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible by one of ordinary skill in the art without departing from the area and scope of the present disclosure, as defined in the following (multiple) claims. Therefore, it is intended that the present disclosure not be limited to the described embodiments, but that it has the wide range of equivalents under the following claims, and their equivalents.

Claims

1. A cable having a plurality of conductors terminating in a first connector, the first connector comprising: a connection portion comprising a plurality of pins for facilitating connection to a second connector of opposite gender; a terminal portion comprising a power terminal providing an electrical connection between a power pin of the connection portion and a power conductor extending through the cable; and a positive temperature coefficient (PTC) chip disposed directly on the power terminal and electrically connected in series between the power terminal and the power conductor, wherein the PTC chip is a laminate structure comprising a PTC element having conductive electrodes disposed on top and bottom surfaces thereof, wherein the electrodes on the bottom surface of the PTC element are directly physically connected to the power terminal, wherein the entire width of the electrodes on the bottom of the PTC chip are directly connected to the power terminal, and wherein the first connector further comprises a conductive lead pad disposed on the electrodes on the top surface of the PTC element. the power conductor is directly physically connected to the electrodes on the top surface of the PTC element.

2. The cable of claim 1, wherein, the PTC element has a trip temperature in the range of 80 degrees Celsius to 130 degrees Celsius.

3. The cable of claim 1, wherein, the PTC element is adapted to attenuate current flowing therethrough when the temperature of the PTC element exceeds the trip temperature.

4. The cable of claim 3, wherein, the connection portion, the terminal portion, and the PTC chip are at least partially disposed within a substrate.

5. The cable of claim 1, wherein, the first connector conforms to the USB-C standard.

6. The cable of claim 1, wherein, 7. A cable having a plurality of conductors terminating in a first connector, the first connector comprising: a connection portion comprising a plurality of pins for facilitating connection to a second connector of opposite gender; a terminal portion comprising a power terminal providing an electrical connection between a power pin of the connection portion and a power conductor extending through the cable; a ribbon-type lead connected to and extending from the power terminal; and a positive temperature coefficient (PTC) chip disposed directly on the ribbon-type lead and electrically connected in series between the power terminal and the power conductor, wherein the PTC chip is a laminate structure comprising a PTC element having conductive electrodes disposed on top and bottom surfaces thereof, wherein the electrodes on the bottom surface of the PTC element are directly physically connected to the ribbon-type lead, and wherein the first connector further comprises a conductive lead pad disposed on the electrodes on the top surface of the PTC element, wherein the ribbon-type lead is planar and comprises a tongue portion secured to the power terminal and an interface portion secured to the electrodes on the bottom surface of the PTC element, wherein the interface portion has a length and a width at least as great as the length and width of the electrodes on the bottom surface of the PTC element. the lead pad has a thickness of 0.3 millimeters or greater. the power conductor is directly physically connected to the lead pad.

8. The cable of claim 7, wherein, ​ 9. The cable of claim 7, wherein, ​ 10. The cable of claim 7, wherein, The PTC element has a trip temperature in the range of 80 degrees Celsius to 130 degrees Celsius.

11. The cable of claim 10, wherein, The PTC element is adapted to attenuate current flowing therethrough when the temperature of the PTC element exceeds the trip temperature.

12. The cable of claim 7, wherein, The connecting portion, the terminal portion, and the PTC chip are at least partially disposed within a substrate.

13. The cable of claim 7, wherein, The first connector conforms to the USB-C standard.

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