Charging cable dead zone mitigation

Abstract

A charging cable is configured to rotate freely when connected to a rechargeable device cable plug. The plug has contact pads separated by an insulator, and the mating cable connector has pins for contacting the pads of the plug. There may be a "dead zone" position where one or more pins of the cable connector rest on the divider and do not contact the charging pads of the cable plug. Examples include pins in the cable connector for redundant charging paths that are complementary so that only one of the power paths is connected at any given time. When the cable enters a position where one of its power paths rests in the "dead zone", the circuitry in the cable switches to the second power path capable of providing power to the device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Application No. 62 / 785,489, filed on December 27, 2018, entitled “Charging Cable Dead Zone Mitigation,” the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present subject matter relates to a charging cable designed to rotate when connected to a device to be charged and to a technique for mitigating any dead zone effects that may occur due to the cable connector contact pins that may land on the insulator between the charging pads of the chargeable device cable plug.

[0004] background

[0005] Many types of electronic devices, such as portable or wearable devices, have integrated electronics that require an internal power source in the form of a battery. Such devices are coupled to a power source from time to time to charge the battery. This method of charging an electronic device typically uses a charging cable that is connected to an appropriate receiver on the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings illustrate one or more embodiments by way of example only and not by way of limitation. In the drawings, like reference numerals indicate like or similar elements.

[0008] Figure 1 is a high-level block diagram of an example combination or system including a charging cable and a chargeable device, the cable connector and the cable plug on the device being configured for rotatable coupling.

[0009] Figure 2 is an isometric view of an example of a charging cable connector receptacle and a charging device cable plug.

[0010] Figure 3 is included in Figure 2 An enlarged view of the cable connector in FIG. 1 is shown, showing the socket groove for receiving the rechargeable device cable plug, and showing the power (Pwr.) and ground (Gnd.) pins for contacting the rechargeable device cable plug pads.

[0011] Figure 4 is a functional block diagram of an example battery powered rechargeable device.

[0012] Figure 5 is a graph of example current draw of a chargeable device under several conditions and current detection thresholds for indicating cable and device connection via a cable connector and a cable plug.

[0013] Figure 6 is similar to Figure 5Figure 2 is a graph of an example current draw of a rechargeable device and shows the modulation of the current.

[0014] Figure 7 is a functional block diagram of a charging cable example.

[0015] Figure 8 Shown are elements of an example of a cable plug, cable connector pins, and an associated switch for selectively connecting a pair of pins to power and ground forming an interface between the cable and a chargeable device.

[0016] Fig. 9 It is available for Figure 7 Logic diagram of an example of a switch logic circuit in a charging cable.

[0017] Fig.10 , 11 , 12 and 13 are graphs of examples of sensed current variations over time under several different system states.

[0018] Fig.14 Several examples of timing conditions are shown.

[0019] Detailed description

[0020] In the following detailed description, many specific details are set forth by way of example in order to provide a thorough understanding of the relevant teachings. However, it is obvious to those skilled in the art that the present teachings can be implemented without these details.

[0021] The following description of embodiments is intended to be read in conjunction with the accompanying drawings, which are considered part of the entire written description. In the description, related terms such as "right", "left", "lower", "upper", "horizontal", "vertical", "above", "below", "upward", "downward", "top", "bottom" and their derivatives (such as "horizontally", "downward", "upward", etc.) should be interpreted as referring to directions as described at the time or as shown in the drawings being discussed. These related terms are for convenience of description and do not require that the instrument be constructed or operated in a specific orientation. Terms related to connection, coupling, etc., such as "coupled", "connected" and "interconnected", refer to a relationship in which each structure is directly or indirectly fixed or connected to each other through an intervening structure, and two structures form a removable or rigid connection or relationship, unless otherwise expressly stated.

[0022] Various examples disclosed herein relate to cables used in charging battery-powered electronic devices, wherein a cable connector rotatably connects the cable to a compatible plug on the electronic device and to cable circuitry and potentially to the chargeable device to mitigate any potential dead zone effects.

[0023] The charging cable may be designed to rotate freely when connected to a downstream rechargeable device. In the examples described below, the cable includes a power bus and a ground bus and a cable connector having a socket recess and an inwardly protruding pin that couples to the bus for electrical connection to a battery-powered device to be charged. The rechargeable device has a cable plug for insertion into the socket recess of the cable connector when the cable is coupled to the rechargeable device.

[0024] The cable plug includes two charging contact pads made of a suitable conductive material (such as a rigid, durable, conductive metal) separated by an insulator such as a suitable plastic. In this example, the charging contact pad surfaces are exposed at different locations around the approximately cylindrical surface of the cable plug for possible pin contact, such as mounted and exposed on opposite sides of the cylindrical surface, wherein the area of ​​the separator isolates the ends or edges of the exposed surfaces of the charging contact pads from each other, thereby possibly forming a dead zone.

[0025] With this cable connector and cable plug configuration, the charging cable (including the cable connector) can rotate freely relative to the plug of the rechargeable battery powered device. However, there may be a position where the charging prongs of the cable connector will not contact the charging pads on the device cable plug because the prongs rest on the plastic separator. In this dead zone position, there is no electrical connection and the charging cable cannot power the device until the user rotates the cable. This may force the user to, for example, move the cable connector out of the dead zone in order to activate or resume charging. The likelihood or probability of the prongs landing on the dead zone may depend on the mechanical width of the plastic separator, tolerances, wear and tear on the receiving piece or cable connector, and user behavior.

[0026] The following example introduces a second power path by providing redundant power and ground pins at the charging cable connector. In a specific example, the two separate power paths are complementary so that only one power path will be turned on at any given time. When the cable enters a position where one of its power paths is in a "dead zone", the logic circuitry of the cable controls one or more switches to change the charging current to a second power path capable of providing power to the device.

[0027] Various forms of detection can be utilized, for example, detecting the coupling of the connector to the cable plug in the receiver and detecting which pins are properly contacting the charging contact pads of the cable plug at any given time. This enables control of a switch to activate the flow of current through the pins of the cable connector, which has appropriate contact with the contact pads of the cable plug of the rechargeable device. The presence of the device can be detected in a variety of ways (e.g., using proximity sensors). However, these examples do not add additional sensor pins or additional contact pads for connection sensing, but rely on sensing the current through the circuit formed by the cable connector and the cable plug. Various current detection techniques can be utilized. For example, the logic of the charging cable can be alternately connected to a pair of pins so that two sets of power and ground pins in the cable connector are used to switch between two power paths when the sensed current is low. When the current sense on one path becomes high, the logic controls one or more switches to selectively maintain the path and stop switching.

[0028] Examples as shown in the following figures and discussed below will now be described in detail. Figure 1 1 shows an example of an overall combination of elements forming a system 10. As shown, the system 10 includes a rechargeable device 11 and a charging cable 15. Figure 4 As shown, the rechargeable device 11 includes a device circuit 17 including a battery and a battery charger circuit coupled to the battery. The rechargeable device 11 also includes a cable plug 19 including first and second charging contact pads coupled to supply power to the battery charger circuit. The insulator electrically isolates the contact pads. Figure 2 or Figure 8 In the example shown, the charging pad includes a power contact pad coupled to the battery charger circuit, a ground contact pad coupled to the chargeable device ground, and an insulator between the power contact pad and the ground contact pad. However, it is apparent that the contact points or contact pads of the plug do not have to be strictly power or ground contacts, and either pad can serve an alternative function. For convenience only, further discussion of the non-limiting example sometimes refers to a particular contact point or pad as a power contact pad, and another contact point or pad as a ground contact pad.

[0029] The charging cable 15 includes a connection to a power source. The power connector in this example is a male USB connector 21, although other types of connectors and associated power sources may be used. Although not necessarily part of the system 10, the figures also show a compatible power source, which in the example using the USB connector 21 would be a USB power source 23. Examples of USB power sources 23 include a computer, a wall adapter, or a car charger, where the female USB port is configured to receive the male USB connector 21 of the charging cable 15.

[0030] The charging cable 15 in this example includes an insulated wiring harness 25 that includes a power bus 27 and a ground bus 29. Other wires or buses may be included for other purposes. In this example, the wiring harness connects the USB connector 21 to the cable circuit 31, and the cable circuit 31 is connected to the cable connector 33. However, the arrangement shown is a non-limiting example, and other arrangements of cable elements may be used. In an alternative configuration, there may be an additional wiring harness between the cable circuit 31 and the cable connector 33, or in another alternative configuration, the cable circuit 31 may be connected to the USB connector 21 or integrated with the USB connector 21 (with power and ground buses inside the circuit 31 or connector 21), and a slightly different cable harness connects the circuit 31 to the cable connector 33.

[0031] At a high level, the cable connector 33 has a groove that is configured to receive the cable plug 19 when the connector 33 of the cable 15 is rotatably coupled to the cable plug 19 of the rechargeable device 11. Figure 2 and Figure 3 , the cable plug 19 and the cable connector 33 are discussed in more detail. Examples of cable circuits will be referred to later. Figure 7-9 Have a discussion.

[0032] Reference now Figure 2 , the cable plug 19 is shown as a cylindrical terminal post extending from a wall 41 of a rechargeable device housing or the like. Although other shapes may be used, a fairly round cylindrical shape is particularly effective in enabling rotation of a cable connector having an appropriately shaped mating socket recess. The figure shows an example of a cable connector 33 in the form of a cylindrical socket 43 connected laterally to the end of a wiring harness 25. For convenience, Figure 2 In this illustrative example, the cable plug 19 is exposed on the outer surface of the rechargeable device housing, and there are no adjacent obstacles that could affect or interfere with the rotation of the cable around the cable plug 19 when the plug 19 and the cable connector 33 are coupled together for device charging.

[0033] Although not shown, the cable plug 19 may be embedded as part of the receiving member in the device, with other components of the cable (e.g. Figure 1The wiring harness 25 or circuit 31 in the charging device 40 can be axially connected to the end of the cable connector socket 43 (for example, connected to the top side in the direction shown), which is opposite to the socket groove for receiving the cable plug 19. In this arrangement, the charging receiving piece on the device will include a cylindrical groove that is slightly larger than the perimeter of the outer side of the cylindrical socket 43, and the cable plug 19 is approximately located in the center of the groove. However, if the rechargeable device does not have such a receiving piece with a cylindrical groove, the outer shape of the socket 43 does not need to be cylindrical and can have some other design or shape, for example, to facilitate the user to grasp the cable connector socket 43 to couple the socket to the cable plug 19 or rotate the socket 43 around the axis of the cable plug 19.

[0034] The cable plug 19 is configured to be inserted into a cylindrical recess of the socket 43 of the cable connector 33. Figure 3 The cable plug 19 includes two charging contact pads of a suitable conductive material (e.g., metal) separated by an insulator such as a suitable plastic. Various configurations of pads and separators may be used. In the following example ( Figure 8 ), metal sheets of appropriate shape form the majority of the plug and serve as contact pads. Electrically insulating separators between the metal sheets complete the cylindrical body of the plug.

[0035] However, Figure 2 The example utilizes a terminal post 45 made of plastic or another insulating material. The terminal post 45 is generally cylindrical in shape. Each contact pad 47 and 49 is formed of a suitable conductive material such as metal. At least some surface area of ​​each of the contact pads 47, 49 is exposed for electrical contact, possibly through one or more pins of the socket 43 of the cable connector 33. Figure 2 As shown, the contact pads 47, 49 are positioned to present exposed contact surfaces at different locations around the cylindrical side surface of the terminal 45 of the cable plug 19. In the illustrated orientation, the first (1) charging contact pad 47 is mounted on the left side of the cylindrical side of the terminal 45, and the second (2) charging contact pad 49 is mounted on the opposite (right) side of the cylindrical side of the terminal 45.

[0036] The metal forming the contact pads may be deposited on the cylindrical side of the terminal post 45, in which case the contact pads 47, 49 may be slightly elevated or extend outward from the cylindrical outer side of the terminal post 45. Alternatively, the metal forming the contact pads 47, 49 may be embedded in the material of the terminal post 45 and have a certain thickness to form a smooth cylindrical side surface of the plug 19. In another optional example, the metal forming one or both of the contact pads 47, 49 may be sufficiently embedded to form one or more slight depressions in the cylindrical side of the plug 19. However, in either of these structures, the surfaces of the pads 47, 49 are exposed for mechanical and electrical contact with the pins in the cable connector receptacle 43.

[0037] exist Figure 2 In the example of the embodiment, the insulating material of the terminal 45 provides structural support for the contact pads 47, 49 and forms a separator between the contact pads to electrically insulate or isolate the contact pads 47, 49 from each other. The insulating material separates the metal of the contact pads on opposite sides of the plug structure (e.g., laterally across the vertical axis of the terminal 45 in the direction shown). The example plug structure has an exposed portion on the cylindrical outer side of the insulating material of the terminal 45, located between adjacent ends of the exposed surface of the contact pads 47, 49. One of the exposed portions 51 on the cylindrical surface of the terminal 45, located between the ends of the contact pads 47, 49, is visible in the direction shown. A similar second portion is located on the opposite (rear) side of the cylindrical terminal 45 and is not visible in the drawings. Such an area (e.g., 51) of the plastic terminal that separates the ends or edges of the surfaces of the contact pads 47, 49 forms a dead zone in which the pins of the socket 43 may not complete the circuit due to the inability to contact the pads of the cable plug 19.

[0038] However, each exposed insulating region 51 can be relatively small to minimize the size of the dead zone. For example, the region 51 only needs to be large enough to prevent current from flowing from one end of a contact pad through the region to the adjacent end of the other contact pad. In another example, the region 51 can be slightly wider than the width of the pins of the cable connector 33 (or the maximum width of the pins), so that the pins in the cable connector cannot contact two contact pads 47, 49 at the same time.

[0039] Figure 3 4 is an enlarged isometric view of the socket 43 of the cable connector. The socket 43 is shown from this perspective to have a cylindrical recess 55 for receiving a chargeable device cable plug. Although other shapes may be used, the illustrated example has a cylindrical socket recess 55 that is slightly larger than the cylindrical side of the cable plug so that when the plug is inserted / received in the socket recess 55, the cable connector socket 43 can rotate freely relative to the plug.

[0040] Figure 3 Also shown are the power (Pwr.) and ground (Gnd.) pins of the cable connector for contacting the gasket of the cable plug on the rechargeable device. As shown, the socket 43 includes two power pins 57a and 57b and two ground pins 59a and 59b. In this example, the pins are located at four equidistant positions around the cylindrical inner wall of the socket groove 55. The power pins 57a, 57b protrude into the socket groove 55 of the cable connector, and the ground pin protrudes into the socket groove 55 of the cable connector. The pins protrude sufficiently to allow contact with the gasket of the cable plug. Although not shown, the pins can be spring pins or deformable pins in the socket to provide a lateral force against the plug surface (including the contact gasket surface), and the plug is received in the socket groove.

[0041] When the power pin 57a ​​and the ground pin 59a contact Figure 2 When the power pin 57a ​​and the ground pin 59a contact the contact pads 47 and 49 of the cable plug 19, the power pin 57b and the ground pin 59b provide a charging current path. Similarly, when the power pin 57b and the ground pin 59b contact the contact pads 47 and 49 of the cable plug 19, the power pin 57b and the ground pin 59b provide another charging current path. Figure 2 The exemplary arrangement of the gaskets shown and Figure 3 As shown in the pins, at the rotational position of the socket 43 relative to the cable plug 19, the pins 57b, 59b contact the area 51 forming the dead zone, and a pair of pins 57a, 59a contact the contact pads 47, 49 of the cable plug 19. At another rotational position of the socket 43 relative to the cable plug 19, the pins 57a, 59a contact the area 51 forming the dead zone, and the other pair of pins 57b, 59b contact the contact pads 47, 49 of the cable plug 19.

[0042] In other positions, a pair of pins 57a, 59a and 57b, 59b simultaneously contact pads 47, 49 of the cable plug 19. When both pairs of pins contact the pads, one pair of pins has the correct polarity, for example, the power pins contact the contact pads for power on the cable plug, and the ground pins contact the contact pads for grounding on the cable plug. Figure 2 and Figure 3The exemplary arrangement provides a high percentage probability that there is a proper polarity connection with the contact pad of the cable plug via one of the pin pairs of the socket 43 of the cable connector 19. For those rotational positions where both pin pairs contact the cable plug pad at the same time, the pin pair of the proper polarity contacts the pad. For each pin pair that contacts the dead zone, there are two rotational positions 180 degrees apart in which the corresponding pin pair contacts the dead zone. In these two positions, the other pin pair contacts the contact pad of the cable plug, and in one of these dead zone positions, the other pin pair has the proper polarity alignment for the charging current to flow. Only in one dead zone position per pair does the other pin pair have the wrong polarity contact, thereby preventing the charging current from flowing. Therefore, in only one rotational position per pin pair, the dead zone and polarity mismatch prevent charging. However, in this rare case, a small rotation will cause the pins to leave the dead zone, both pairs of pins contact the contact pad of the cable plug, and one pair has the proper polarity to allow current to flow.

[0043] In order to utilize a redundant charging current path through a pair of pins in a cable connector and avoid polarity mismatch, the cable includes one or more power path switches for selectively connecting different power pins to a power bus and selectively connecting different ground pins to a ground bus in respective different states. A current sensor is coupled to at least one bus to detect current through a selected pair of pins of the cable connector. The switching logic circuit in the cable is configured to control the one or more power path switches to establish a charging connection through a selected pair of pins (coupling a selected one of the power pins to the power bus and coupling a selected one of the ground pins to the ground bus). In response to the current sensor detecting current flow through the selected power pin and ground pin, the logic maintains the switch connection of the pins to the bus through which current is detected to flow. Examples of this method also detect pulse modulation of current by the circuit of the rechargeable device. Reference Figure 4 The initial figures illustrate this specific example.

[0044] Figure 4 is a functional block diagram of an example of components of a battery powered rechargeable device 11, such as Figure 1 As shown, the rechargeable device 11 includes a device circuit 17 and a cable plug 19. The cable plug 19 in this device example can be as described above with respect to Figure 2 and Figure 3 as discussed above, or as later with respect to Figure 8 The rechargeable device 11 includes a cable plug 19, which includes a pair of charging contact pads, such as Figure 2 or Figure 8 As shown, for example, as a power contact pad and a ground contact pad. The power contact pad is coupled to the power supply of the battery charger circuit 63 at the VBUS port.

[0045] The device circuit 17 includes a battery 61 and a battery charger circuit 63 coupled to the battery 61. The positive terminal of the battery 61 is connected to the battery charger circuit 63, and the negative terminal of the battery 61 is connected to the ground of the rechargeable device 11. For convenience, the device electronics that can obtain power from the battery 61 to complete the general functions of the device (except for the charging functions considered herein) are omitted. The charging cables and charging techniques discussed herein can be applied to any of a variety of portable or wearable devices that utilize rechargeable batteries to power specific electronic components or act as a battery pack to power other devices.

[0046] The device circuit 17 includes a switch 65 that is coupled to consume current from the battery charger circuit 63. For example, based on the type and size of the battery 61, a variety of known circuits can be used to implement the battery charger. The switch 65 is controlled so that a particular type of battery charger circuit 63 adds pulse modulation to the current passing through the charging path formed by the cable plug 19 and the cable connector 33. Any switching device configured to switch a suitable amount of current can be used, such as any of a variety of switching transistors. For example, the accompanying drawings show a field effect transistor (FET) as the switch 65. Various switch connections to the battery charger 63 and possible various intermediate or related circuit elements can be utilized. In this example, the switch 65 is connected to the switch (SW) port of the battery charger circuit 63 via a series connection of a resistor R1 and an inductor LI. A path is also provided from the connection point between the inductor LI and the resistor R1 to the system voltage port (VSYS) of the battery charger circuit 63. The switch 65 in this example is connected in series from the resistor R1 to the ground of the rechargeable device.

[0047] When switch 65 is in its open state, battery charger circuit 63 consumes current to charge battery 61. When switch 65 is in its closed state, the current flowing through switch 65 to ground causes battery charger circuit 63 to consume an additional amount of current through the charging path formed by cable plug 19 and cable connector 33. As discussed later, switching back and forth between the open and closed states of switch 65 generates pulses and causes battery charger circuit 63 to superimpose corresponding pulses on the current through the charging path formed by cable plug 19 and cable connector 33. The generated pulses can be detected by the cable circuit.

[0048] The device circuit 17 also includes a device controller. Although other controllers can be used for implementation, the example device uses a microcontroller unit (MCU) 67. The MCU is typically a system on a chip (SoC) that includes a processor, memory, peripheral input / output (I / O) interfaces and ports, and possible other circuit components. For example, a single SoC may include a battery charger circuit as well as circuits forming an MCU. For the purposes of this discussion, the MCU 67 controls functions related to battery charging, although the MCU may perform other functions relative to the device 11 depending on the device type or application of the specific electronic device 11. However, it should be apparent that other controllers may be used for implementation. The functions of the MCU 67 are determined by executable program instructions or configuration data (e.g., as firmware) installed in the MCU memory.

[0049] In the example rechargeable device 11, the MCU 67 forming the device controller is responsive to power from the cable plug 19 and is configured to operate the switch 65 to cause the charger circuit 63 to pulse the current through the cable plug 19 as an indication that the pins in the cable connector are in contact with the power and ground contact pads of the cable plug 19 to the circuit 31 of the charging cable 15 (see Figure 1 ).

[0050] The battery charger circuit 63, or control of the circuit 63 by the MCU 67, configures the device circuit 17 to implement a regulated current profile for charging the battery 61 over a period of time. Figure 5 for Figure 1 and Figure 4 Graph of example current draw for charging an example rechargeable device 11 battery. The current levels at various stages of the graph are given by way of example only. The device 11 may implement different current levels or graphs with different stages, for example, to address the charging requirements of a particular type of battery 61 used in a particular rechargeable device 11. Figure 5 In the example of FIG. 1 , when the device 11 is coupled to the charging path via the cable plug 19, the regulated current flow is realized Figure 5 Several states of the curve graph. In the initial state, the battery charging circuit 63 consumes about 100 mA for pre-charge or trickle charge current. At a later time, such as when specific conditions for MCU operation or battery charging are met, the battery charging circuit 63 consumes a constant charging current of about 500 mA for fast full power charging of the battery 61. At a later time, such as when the battery reaches a specific threshold of the charge percentage, the battery charging circuit 63 consumes current to apply a constant voltage to the battery. In this third state, while the voltage remains constant, the current slowly decreases until the battery is fully charged and the device 11 reaches the end of charge (EOC) state at the minimum current level.

[0051] As described above, various techniques (e.g., proximity sensing) may be used to detect the presence of a plug inserted into a cable connector, or various techniques may be used to detect the connection of a charging current through the cable connector pins and the cable plug contact pads. The examples discussed below utilize sensing of current through a charging circuit formed by the pins of the cable connector and the contact pads of the cable plug. Figure 5 Also shown is a current detection threshold (I_detect) for controlling path switching in response to current sensing. As discussed later, the charging cable circuit 31 ( Figure 1 ) detects current on the connection path through the cable connector and the cable plug. Sensing current flow on the connection path at or above the I_detect threshold is used as an indication of the connection of the cable 15 and the chargeable device 11 via the cable connector 33 and the cable plug 19. Although other thresholds may be used, this example shows a current detection threshold (I_detect) of approximately 60 mA. Figure 5 The example graphs and I_detect shown show that the current draw of the charging path through the cable connector and cable plug exceeds the I_detect threshold during the pre-charge or trickle state, the constant current state, and most of the constant voltage state.

[0052] When the battery is close to being fully charged in the later stage under the constant voltage state, the current consumption of the charging path through the cable connector and the cable plug is lower than the I_detect value used by the cable for connection detection. Moreover, the current consumption in the end of charge (EOC) state is lower than the I_detect value used by the cable for connection detection. Figure 4 The example device circuit 11 introduces pulse modulation to mitigate potential failures of the cable circuit, thereby Figure 5 The connection is detected in these later situations in the charging current graph.

[0053] When the battery is fully charged, at the EOC state of the graph shown, it is still necessary to sense the current to indicate to the cable circuit that the rechargeable device is still electrically connected. A variety of techniques can be used to assist in this detection. For example, the rechargeable device can be configured to consume a low level of current flow sufficient to trigger the I_detect threshold. If a current sensor with a sufficiently low threshold is used, any current flow will work. For example, the idle system current consumption of the rechargeable device may itself be sufficient to trigger the threshold depending on the type, configuration, or application of the rechargeable device.

[0054] To achieve lower power consumption in low current states, the example system discussed below adds pulse modulation to the current draw. In situations where the current draw of the rechargeable device might otherwise drop below the I_detect threshold, the periodic peaks of the modulated current meet or exceed the I_detect threshold. Figure 6 is similar to Figure 5A graph of an example current draw of a rechargeable device also shows this pulse modulation of the current.

[0055] As above relative to Figure 4 As described above, the MCU 67 operates the switch 65 to pulse-modulate the current passing through the cable plug 19 . Figure 6 The current graph of shows modulated pulses superimposed on the current flow by the opening and closing of switch 65, at least in a state where the level of current flow would otherwise fall below the I_detect threshold level. The pulse peaks of the modulated current rise to a level equal to or above the I_detect threshold level. Based on proper timing of the cable circuit 31, the cable 15 is able to sense current pulse peaks that periodically exceed the I_detect threshold level as an indication that the current connection pins of the cable connector 33 are in contact with the power and ground contact pads of the cable plug 19, which contact is sufficient to establish a charging path with the battery charger circuit 63 of the rechargeable device 11.

[0056] Figure 7 15 is a functional block diagram of an example of a charging cable 15. Wiring to a USB type power source (see Figure 1 ) include Figure 7 The power bus 27 shown as VBUS in FIG. 1 is used for a USB compatible cable. The wiring connected to the USB type power supply also includes a ground bus 29.

[0057] The cable circuit 31 of this example includes a protection circuit 71 that provides one or both of overvoltage protection (OVP) or overcurrent protection (OCP). Power from the protection circuit 71 flows through a current sensor 73 to a power path switch hardware 75. Figure 7 and Figure 8 The example shown in FIG. 5 includes two pairs of power and ground pins, one pair is shown including power pin 57a ​​and ground pin 59a and the other pair includes power pin 57a ​​and ground pin 59a.

[0058] Figure 7 The power path switch hardware 75 includes one or more power path switches selectively coupled between the pin and the bus (through the sensor 73 and the protection circuit 71). Figure 8 In a more specific example of FIG. 7 , the power path switch hardware 75 is shown in two parts 77p, 77g, which together include four switches 81-84, one for each pin of the cable connector. For each switch 81-84, any switching device configured to switch the appropriate amount of current can be used, such as any of a variety of switching transistors. For example, the figure shows a field effect transistor (FET) as each switch 81-84.

[0059] The power path switch hardware portion 77p is connected to the power bus 27 and includes switches 81 and 83 connected to the power pins 57a, 57b, respectively. The power path switch hardware portion 77g is connected to the ground bus 29 and includes switches 82 and 84 connected to the power pins 57a, 57b, respectively. Selective operation of switches 81, 82 connects and disconnects the pins 57a, 59a of the first pair to the power bus 27 and the ground bus 29. Selective operation of switches 83, 84 connects and disconnects the pins 57b, 59b of the second pair to the power bus 27 and the ground bus 29. The pins 57a, 57b form a first pair for contacting pads of a cable plug. The pins 57b, 57b form a first pair for contacting pads of a cable plug.

[0060] In the relative rotational position shown, the power pin 57a ​​contacts the power pad 85 and the ground pin 59a contacts the ground pad 87. In these positions, the first pair of pins 57a, 59a and the pads 85, 87 form a charging path of the appropriate current flow polarity. A pair of pins 57b, 59b contacts the pads, but with opposite polarity, with the power pin 57a ​​contacting the ground pad 87 and the ground pin 59b contacting the power pad. When switches 81, 82 connect pins 57a, 59a to the bus, the connection establishes a charging path for current to flow through the cable connector and the cable plug. In this switched state, switches 83, 84 disconnect pins 57b, 59b, thereby disabling the opposite polarity configuration.

[0061] Figure 8 Also shown is an alternative embodiment of a cable plug 19a of a rechargeable device inserted into a cable connector and in contact with the various pins 57a, 57b, 57a, 57b of the cable connector. In the example shown, the cable plug 19a includes two metal pieces of appropriate shape, which form the majority of the plug, serving as power contact pads 85 and ground contact pads 89. The cable plug 19a in the drawings has an electrically insulating partition between the metal pieces, which completes the cylindrical body of the plug and forms a dead zone 89 with respect to the current flow between the pins of the cable connector and the pads of the cable plug 19a.

[0062] The cable circuit 31 in this example includes a logic circuit 77 ( Figure 7 ). The logic circuit can be implemented using another MCU similar to the one used as the charging controller MCU in the rechargeable device example. Fig. 9 The specific examples of logic circuits discussed herein are substituted for using specific logic components, for example, in light of size and cost constraints applicable to the charging cable 15 .

[0063] The switch logic circuit 77 receives a signal (I-SENSE) from the current sensor 73, which is a voltage value representing the instantaneous magnitude of the sensed current flowing through the sensor and therefore through the power path switch hardware 75 and the cable connector 33. In this example, the switch logic circuit 77 responds to the detected current indicated by the signal (I-SENSE) from the current sensor 73 and outputs selection signals EN1 and EN2 to the power path switch hardware 75. In one state, the selection signal causes one or more switches of the power path switch hardware 75 to selectively connect the first pair of pins 57a, 59a to the power and ground bus. In another state, the selection signal causes one or more switches of the power path switch hardware 75 to selectively connect the second pair of pins 57a, 59a to the power and ground bus.

[0064] exist Figure 7 and Figure 8 In the example of , the EN1 and EN2 control signals have opposite states, one signal is high when the other signal is low, and vice versa. Switches 81-84 use two different types of FETs to respond inversely to the states of their corresponding inputs. For example, FET switches 81 and 83 can be closed in response to a high input and open in response to a low input. In such an example, FET switches 82 and 84 can be closed in response to a low input and open in response to a high input. FET switches 81 and 83 open and close in response to the state of the EN2 control signal.

[0065] In this arrangement, a high value of EN1 closes switch 81, connecting power pin 57a ​​to power bus 27, and opens switch 84, disconnecting ground pin 59a from ground bus 29. At the same time, an opposite low value of EN2 opens switch 83 to disconnect power pin 57b from power bus 27, and closes switch 82 to connect ground pin 59a to ground bus 29. In this state, a pair of pins 57a, 59a are connected to buses 27, 29, and a pair of pins 57b, 59b are disconnected. In the alternating states of the EN1, EN2 signals, a low value of EN1 opens switch 81 to disconnect power pin 57a ​​from power bus 27, and closes switch 84 to connect ground pin 59a to ground bus 29. At the same time, an opposite high value of EN2 closes switch 83 to connect power pin 57b to power bus 27, and opens switch 82 to disconnect ground pin 59a from ground bus 29. In this state, a pair of pins 57b, 59b are connected to the bus lines 27, 29, and a pair of pins 57a, 59a are disconnected.

[0066] In each state, the power path switch hardware 75 connects a corresponding one of the power pins (57a or 57b) to the power bus 27 and a corresponding one of the ground pins (59a or 59b) to the ground bus 25. The two charging paths and their switches are complementary in this example because only one pair of power pins and ground pins are connected to the power bus and the ground bus to allow current to flow in each state. At a high level, the switch logic circuit 77 is configured to maintain a connection via the selected pair of power and ground pins (connected to the power bus and the ground bus, respectively) to provide a charging path for current flowing through the cable connector and the cable plug of the chargeable device, in response to current flow (I_SENSE) detected by the current sensor via the selected pair of power and ground pins.

[0067] In the example, the switch logic circuit 77 is configured to operate the power path switches 81-84 to alternately connect the corresponding pair of power and ground pins to the power and ground buses when the current detection of the current sensor is below the threshold value I_detect. In other words, the switch logic circuit 77 regards the condition that the detected current flow value I_SENSE is below the threshold value I_detect as an indication that a feasible charging current flow path has not yet been established. The cable plug may not have been inserted into the receptacle of the cable connector, and a pair of pins have been switched to connect to the bus currently resting on the exposed area of ​​the insulating partition forming the dead zone 89, or a pair of pins have been switched to connect to the bus currently contacting the pads in opposite polarity order (power pin to ground pad and ground pin to power pad).

[0068] In an example, the switch logic circuit 77 is also configured to establish a charging path by maintaining a connection to a power bus via a selected power pin and a connection to a ground bus via a selected ground pin (without other alternative connections). The switch logic circuit 77 stops switching and maintains the connection of the charging path in response to detecting a current equal to or above a threshold through a pair of pins including a power pin and a ground pin. The situation where the detected current flow value I_SENSE is equal to or above the threshold value I_detect indicates that the cable plug is inserted into the socket of the cable connector, a pair of pins have been switched to connect to the bus currently resting on two contact pads of the cable plug, and a pair of pins have been switched to connect to the bus currently contacting the pads in the appropriate polarity sequence for DC charging flow (power pin to power pad and ground pin to ground pad).

[0069] Fig. 9An example of a logic circuit arrangement for current responsive switching and switches for implementing pin connection current detection implemented by the above-described charging path connection logic is shown. The example switch logic circuit 77 includes a comparator 87. A voltage I_SENSE from a current sensor proportional to the sensed current is coupled to the negative input of the comparator 87. A voltage reference I_DETECT corresponding to an appropriate value of the I_detect current threshold is coupled to the positive input of the comparator 87. With the connection of the positive and negative inputs exemplarily shown in the figure, when the voltage I-SENSE is lower than (less than) the reference voltage I_DETECT, the comparator 87 provides a relatively high output voltage, and when the voltage I_SENSE is equal to or higher than (greater than or equal to) the reference voltage I_DETECT, the comparator 87 provides a relatively high output voltage.

[0070] The example switch logic circuit 77 includes a counter 89 that responds to the output of the comparator 87 and a clock (C1k). When the input from the comparator 87 to the counter 89 is high (in this case, when the current indicated by the voltage I_SENSE is below the reference voltage I_DETECT corresponding to the current threshold), the counter 89 will periodically output pulses (each count of clock pulses reaches a count value corresponding to the time interval t_FET), indicating that there is no feasible current charging path connected through the pair of power and ground pins currently connected to the cable connector.

[0071] The example switch logic circuit 77 includes a switching circuit 91 configured to switch between a high output state and a low output state in response to periodic detection of rising edges of periodic pulses output from the counter 89. Thus, the output of the switching circuit 91 switches back and forth between the high output state and the low output state in response to rising edges of consecutive periodic pulses output from the counter 89. While the current indicated by the voltage I_SENSE is below the reference voltage I_DETECT corresponding to the current threshold, it indicates that there is no feasible current charging path connected through the pair of power and ground pins currently connected to the cable connector.

[0072] The example switch logic circuit 77 also includes a delay and filter circuit 93 that responds to the state of the switch circuit 91. The delay and filter circuit 93 outputs the EN1 control signal to Figure 8 Power path switches 81 and 84 are shown. As a result of the delay function, each transition of the EN1 control signal going high or low for changing the state of power path switches 81 and 84 is followed by a predetermined delay interval by a corresponding high or low transition of the output of switching circuit 91. The filter function is used to clean up any transients from the EN1 signal.

[0073] When EN1 is high, EN2 is low. When EN1 is low, EN2 is high. As described above, in the state where EN1 is high and EN2 is low, switches 81, 82 connect pins 57a, 59a to buses 27, 29, and switches 83, 84 disconnect pins 57b, 59b. Conversely, when EN1 is low and EN2 is high, switches 81, 82 connect pins 57a, 59a, and switches 83, 84 connect pins 57b, 59b to buses 27, 29.

[0074] As long as the I_SENSE voltage is below the reference voltage I_DETECT, the switching between the states continues to repeat, indicating that the current flowing to the chargeable device is below the I_detect current value for a period longer than the time interval t_FET of the counter 89. First, one pair of pins is connected to the power bus and the ground bus, then another pair of pins is connected to the power bus and the ground bus, and so on.

[0075] In the example arrangement of the switching logic circuit 77 shown, when the voltage I_SENSE reaches the reference voltage I_DETECT, the output of the comparator 87 goes low and remains low as long as the voltage I_SENSE remains at or above the reference voltage I_DETECT. During this period, the counter 89 stops counting and does not output any new pulses to the switching circuit 91. The switching circuit stops switching and remains in its last output state (high or low).

[0076] More specifically, the delay in the transition of the EN1 and EN2 switch control signals keeps switches 81-84 in their respective states for a period of time so that the current flow transitions when the charging circuit begins to consume the charging current. When the current begins to flow, such as in the pre-charge or trickle charge state, the current meets or exceeds the I_detect current threshold. The sensor output voltage I_SENSE will then exceed the voltage reference I_DETECT value corresponding to the current threshold. When the comparator 87 changes state, its output goes low, stopping the counter. In response, the switching circuit 91 stops switching and maintains its last high or low state that resulted in successful current detection. For example, if the switching output is high, the switching circuit 91 continues to output a high voltage, EN1 remains high, and EN2 remains low. The switch maintains the connection between pins 57a, 59a and the bus, and the switch maintains pins 57b, 59b. The charging current flows through a path including pins 57a, 59a and the contact pads of the cable plug. If the switching output is low, the switching circuit 91 continues to output a low voltage, EN1 remains low, and EN2 remains high. The switch maintains the connection of pins 57b, 59b to the bus, and the switch maintains pins 57a, 59a disconnected. The charging current flows through a path including pins 57b, 59b and the contact pads of the cable plug.

[0077] Figures 10 to 13 Shown in a similar Figure 1 An example of sensed current over time for several different states of the system 11 . Fig.10 shows when the battery charger has reached the end-of-charge (EOC) low current state (see also Figure 6 ) Pulses of current flow, including current modulated pulses from rechargeable devices. 6). Device circuits ( Figure 4 ) is configured to generate a modulation pulse of sufficient size so that the current is above the I_detect threshold, so that the peak value of the I_SENSE output voltage exceeds the I_DETECT reference voltage used by comparator 87, resulting in a periodic low output from the comparator to the input of the counter when the cable circuit senses a peak current level exceeding the I_detect of the modulation pulse. Each low detection pulse from comparator 87 resets counter 89. The time interval when the modulation pulse is high is referred to as t_high, and the period when the modulation pulse is low is referred to as t_low. The time period (t_FET) that counter 89 periodically emits pulses is greater than the length of time (t_low) that the current modulation remains low, so that if a pulse is detected again before t_FET is turned off, counter 89 does not output any pulses to activate switching circuit 91 as an indication that the cable connector 33 and cable plug 19 are still coupled together and that the currently connected pair of pins provide a charging path of the appropriate polarity via the plug contact pads.

[0078] Fig.11 and Fig.10 Similar, except that the initially connected pair of pins falls on a dead band of the current path that disables the connection. Therefore, at some point after the pulse is detected, the voltage from the comparator remains high for a longer period of time and the period t_FET of the counter 87 expires. The pulse generated by the timeout of the counter 89 activates the switching circuit 91, which causes the switching of various switches to switch to another current path via another pair of pins. When the newly connected pair of alternating pins are properly connected to the pads of the cable plug, current can flow to the battery charger circuit 63. The MCU causes the rechargeable device circuit to resume periodic activation of the switch 65 to pulse modulated current flow, beginning after an interval t_resume_pulse after switching to the alternating current path. The current flow during the interval t_resume_pulse provides sufficient current to at least activate the MCU to resume the pulse. Now in the alternating state, the circuit 31 of the charging cable 15 detects subsequent modulated pulses, such as Fig.10 In this example, the time interval t_FET of the counter is greater than the time interval t_resume_pulse of the rechargeable device resuming pulse modulation (t_FET>t_resume_pulse).

[0079] like Fig.12 As shown, in the normal charging state, the current continuously exceeds the current detection threshold I_detect. In this state, the charging current itself is sufficient for sensing by the comparator of the cable circuit. The voltage from the comparator remains high, the counter does not count clock pulses, there are no pulses to trigger the switching circuit, and the logic and path switching hardware maintain the connection of the pins of the cable connector, which provides a charging path with the appropriate polarity for the charging current to flow to the battery charger circuit.

[0080] Fig.13 A change of state is shown, for example, if a user rotates the charging cable connector coupled to the cable plug. When a pair of connected pins falls over the dead band, the current drops below the threshold I_detect for charging current detection. The voltage from the comparator remains high for a longer period after the path interruption time, and the time period t_FET of the counter 89 expires. The pulse generated by the timeout of the counter 89 activates the switching circuit 91, which causes various switches to switch to another current path via another set of pins. When the newly connected pair of alternating pins are properly connected to the pads of the cable plug, current can flow to the battery charger circuit 63. The MCU causes the rechargeable device circuit to resume periodic activation of the switch 65 to pulse modulated current flow, starting after an interval t_resume_pulse after switching to the alternating current path. The current flow during the interval t_resume_pulse provides sufficient current to at least activate the MCU to resume the pulse. Now in the alternating state, the circuit 31 of the charging cable 15 detects subsequent modulated pulses, such as Fig.10 In this example, the time interval t_FET of the counter is greater than the time interval t_resume_pulse of the rechargeable device resuming pulse modulation (t_FET>t_resume_pulse).

[0081] Fig.14 An example of timing conditions relative to the time interval t_FET of the counter is summarized.

[0082] It should be understood that, in addition to the specific meanings set forth in this article, the terms and expressions used herein have the common meanings consistent with these terms and expressions relative to their respective fields of study. For example, the first and second relationship terms can be used only to distinguish an entity or action from another entity or action, without requiring or implying any actual such relationship or order between these entities or actions. The term "includes", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, product or equipment including or including a list of elements or steps not only includes those elements or steps, but can also include other elements or steps that are not explicitly listed or inherent to such process, method, product or equipment. The element with "one" or "an" in front does not exclude the presence of additional identical elements in the process, method, product or equipment including the element without further restriction.

[0083] Unless otherwise indicated, any and all measurements, values, ratings, positions, sizes, dimensions and other specifications set forth in this specification (including the appended claims) are approximate and imprecise. Such quantities are intended to have a reasonable range consistent with the functions to which they are related and the practices in the art to which they are related. For example, parameter values, etc. may vary from the stated quantity by ±10% unless otherwise expressly stated.

[0084] Although the overview has been described with reference to specific exemplary embodiments, various modifications and changes may be made to these embodiments without departing from the broader scope of the disclosed embodiments. These embodiments may be referred to herein, individually or collectively, by the term "invention" for convenience only, and without any intention to voluntarily limit the scope of the application to any single disclosure or inventive concept, even if more than one is actually disclosed.

[0085] The embodiments herein are described in sufficient detail to enable those skilled in the art to implement the disclosed teachings. Other embodiments may be used and derived from the embodiments herein, so that structural and reasonable substitutions and changes may be made without departing from the scope of the present disclosure. Therefore, the detailed description should not be construed as having a limiting meaning, and the scope of the various embodiments is limited only by the appended claims and the full range of equivalents authorized by these claims.

Claims

1. A system comprising: Rechargeable devices, including: Battery; a battery charger circuit coupled to the battery; and a cable plug including first and second charging contact pads coupled to said battery charger circuit power source of said rechargeable device, and an insulator electrically separating said first and second charging contact pads; Charging cable, including: Power bus; Ground bus; a cable connector having a recess configured to receive the cable plug when the cable connector is rotatably coupled to the cable plug of the chargeable device; A power pin protruding into the groove of the cable connector; A grounding pin protruding into the groove of the cable connector; one or more power path switches coupled between the pin and the bus; and A switch logic circuit is configured to control the plurality of power path switches to selectively connect different ones of the power pins to the power bus and selectively connect different ones of the ground pins to the ground bus in corresponding different states.

2. The system of claim 1, further comprising: a current sensor coupled to at least one of the buses to sense current through a selected pair of pins of the cable connector when connected to the bus through the one or more power path switches; wherein the switching logic circuit is coupled to the current sensor and is further configured to maintain a connection to the power bus via a selected one of the power pins and to maintain a connection to the ground bus via a selected one of the ground pins to establish a charging path for current to flow through the cable connector, the cable plug, and the charger circuit of the chargeable device, in response to the current sensor detecting current flow via the selected power and ground pins.

3. The system of claim 2, wherein: When the current detected by the current sensor is below a threshold, the switch logic circuit is further configured to operate the plurality of power path switches to alternately connect corresponding power and ground pin pairs to the power and ground buses; as well as In response to detecting a current equal to or above the threshold through a pair of pins including the one power pin and the one ground pin, the switching logic circuit establishes the charging path by maintaining the connection to the power bus via the selected power pin and the connection to the ground bus via the selected ground pin without further alternating connections.

4. The system of claim 3, wherein: The rechargeable device also includes: a switch coupled to a drain current from the battery charger; and a device controller that, in response to power from the cable plug, operates the switch coupled to the battery charger to pulse modulate current through the cable plug at least when current flow is below the threshold; and In the charging cable: The current sensor is configured to detect a pulse modulation of current exceeding the threshold and passing through the cable plug via the pins of the cable connector; and The switching logic circuit is further configured to maintain the connection between the selected power pin and the power bus and the selected ground pin and the ground bus in response to the detection of the modulation pulse by the current sensor.

5. A charging cable, comprising: Power bus; Ground bus; a cable connector having a recess configured to receive a cable plug of a rechargeable device when the cable connector is rotatably coupled to the cable plug of the rechargeable device; A power pin protruding into the groove of the cable connector; a grounding pin protruding into the groove of the cable connector; one or more power path switches to selectively connect different ones of the power pins to the power bus and selectively connect different ones of the ground pins to the ground bus in respective different states; as well as The switch logic circuit is configured to control the plurality of power path switches to selectively connect a different one of the power pins to the power bus and selectively connect a different one of the ground pins to the ground bus in corresponding different states.

6. The charging cable according to claim 5, further comprising: a current sensor coupled to at least one of the buses to detect current flow through a selected pair of the pins of the cable connector when connected to the bus through the one or more power path switches; wherein the switching logic circuit is coupled to the current sensor and is further configured to maintain a connection to the power bus via a selected one of the power pins, and to maintain a connection to the ground bus via a selected one of the ground pins to establish a charging path for current to flow through the cable connector and the chargeable device, in response to the current sensor detecting current flow via the selected power and ground pins.

7. The charging cable according to claim 6, wherein: The switch logic circuit is further configured to operate the plurality of power path switches to alternately connect the corresponding power and ground pins to the power and ground buses when the current detection of the current sensor is below a threshold; as well as In response to detecting a current equal to or above the threshold through a pair of pins including the one power pin and the one ground pin, the switching logic circuit establishes the charging path by maintaining the connection to the power bus via the selected power pin and the connection to the ground bus via the selected ground pin without further alternating connections.

8. The charging cable according to claim 7, wherein: the current sensor being configured to detect a pulse modulation of current exceeding the threshold and flowing through the cable plug to or from the rechargeable device via the pins of the cable connector; as well as The switching logic circuit is further configured to maintain the connection between the selected power pin and the power bus and the selected ground pin and the ground bus in response to the detection of the modulation pulse by the current sensor.

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