USB connection unit

Abstract

A USB connection unit (1) with a control unit (10) and with at least two USB ports (2a, 2b) connected to the control unit (10) is described. The control unit (10) is configured to detect a power supply request from a USB plug unit (3a, 3b) connected to a USB port (2a, 2b). The control unit (10) is configured to measure the output current actually transmitted via the USB port (2a, 2b) to the power-requesting USB plug unit (3a, 3b) and to reduce power limitations for the other USB ports (2a, 2b) of the USB connection unit (1) if the measured output current is less than a predetermined first limit.

Description

[0001] The invention relates to a USB connection unit with a control device and with at least two USB ports connected to the control device, wherein the control device is configured to detect a power supply request from a USB plug unit connected to a USB port.

[0002] The invention further relates to a method for detecting whether a USB device is connected to a USB port, even if a USB plug unit, such as a USB adapter cable, is plugged into a USB port and there is no power supply requirement or no device is connected that can draw power.

[0003] Conventional USB connection units, also called USB output modules, have multiple USB ports, with the module detecting whether a port is connected to a USB connector, such as an adapter cable or a USB device.

[0004] The USB interface is a manufacturer-independent interface standard that allows various peripheral devices of a computer system to be connected to a main device, such as a computer, via a standardized connector. Before the introduction of this universal interface, computers had a variety of different interfaces, such as serial interfaces, parallel interfaces, keyboard and mouse interfaces, network interfaces, and monitor interfaces. These interfaces were each designed for specific data communication, but with the exception of keyboard and mouse interfaces, they did not provide power to the external device. Therefore, external devices had to be powered separately, for example, with a power adapter. This particularly affected external storage media, scanners, label printers, and so on.

[0005] With the introduction of the USB interface, several of the previously mentioned physical interfaces became obsolete, as either the devices to be connected also had the new USB interface, or there were adapters that converted the USB protocol to the older interface standard. Thus, mobile computers in particular now only had multiple USB ports instead of the conventional interfaces, such as serial or parallel ports. Another advantage of the new USB interface standard was the availability of power for the external device. The voltage was a fixed 5.0 V, and a maximum current of 0.5 A was enabled via a protocol sequence, providing a power output of 2.5 W per port. This power was sufficient for many devices, eliminating the need for an additional power supply.

[0006] This USB interface, particularly in its Micro-USB version, became established as the standard charging interface for mobile phones. However, the maximum available power of 2.5 W was no longer sufficient, leading to the definition of charging currents up to approximately 2.5 A. With a constant charging voltage of 5.0 V, mobile phones could thus be fully charged in one to two hours.

[0007] With the transition to the new USB-C interface standard, the USB-C Power Delivery (USB-PD) standard was developed for power supply. This standard can deliver a variable voltage up to 20 V at a maximum current of 5 A, enabling the transfer of 100 W of power. Further developments envision output voltages up to 48 V at 5 A to achieve power outputs of up to 240 W.

[0008] A USB connection module can have one or more USB-C ports. For example, a module with four USB ports could have a maximum available power output of 960 W, which would quickly lead to overheating of the electronics within the module, as every power conversion involves losses. Even a circuit with a very high efficiency of, say, 95% would still result in losses of approximately 50 W, leading to enormous heat generation in the small space of a module.

[0009] Typically, USB power supplies for modules with multiple USB ports are designed so that the maximum power output of the power supply is less than the sum of the maximum power outputs of the individual ports. This means it's not possible to provide maximum power to all ports simultaneously. The power is distributed across the ports, with the maximum possible power that the power supply can deliver being divided among the individual outputs. This is also known as "power sharing." For example, each output is allocated a minimum power output, and if a connected device has a higher power requirement, it receives more power within the limits of the available capacity.If several connected devices have a higher power requirement that exceeds the total power available from the power supply, the total available power must be divided, which is done according to different strategies and algorithms.

[0010] These strategies don't necessarily require all devices with higher power demands to receive an equal share of the available power; instead, certain devices can be prioritized. For example, if a connected scanner won't function at all with less power than required, it must be provided with the full power, whereas a mobile phone that needs power to charge its battery will simply take a little longer to charge with less power than desired.

[0011] To communicate the desired voltage and current to a USB module, a device communicates with the USB module according to the USB-PD (Power Delivery) standard. The device informs the module of one or more desired voltage-current configurations, and the module communicates the possible voltage-current configurations to the device. They then agree on a mutually acceptable configuration. This requires that both the USB module and the connected device are configured for communication according to the USB-PD standard. For backward compatibility with devices not configured for USB-PD communication, the USB module can detect at least one identification resistor on the constant current (CC) or data lines. If a device is connected that does not communicate according to the USB-PD standard, but an identification resistor is detected, the USB module sets a default value, e.g., 1 / 3.5 V at 3 A (equivalent to 15 W) or 7.5 W upon detection of a BC1.2-compatible device are available. The identification resistor can be integrated into the connected device or an adapter cable. The unit containing at least the identification resistor and connectable to a USB port, i.e., for example, a device, an adapter cable, or a combination of device and adapter cable, is hereinafter collectively referred to as the USB connector unit for the purposes of the invention.

[0012] According to the USB-C Power Delivery standard, a minimum of 7.5W of power must be reserved for each port, even if the USB port is unused, to ensure a minimum power supply for a newly connected device. If each output is allocated a minimum power supply, and the remaining power is distributed among devices with higher power requirements, it can happen that the higher-powered devices have to forgo some of their required power, while the unused ports or the devices connected to the ports with the minimum power supply do not receive their allocated power. This is particularly true when a USB adapter cable is plugged into some ports, but no device is connected to the other end. This situation can occur frequently, as many users simply leave the cable plugged in and unplug the device at the other end.

[0013] These adapter cables, such as an iPhone Type-C to Lightning adapter or a Type-C to Micro-USB adapter, are not simply connecting cables from one connector standard to another, but contain additional components, such as resistors for identification on the CC line. As soon as the cable is plugged into the USB port, the electronics in the USB module detect, via one or more identification resistors, that power is required at that port, regardless of whether a device is connected to the other end of the adapter cable. The USB module then provides power to that port corresponding to the identification resistor value.

[0014] EP 3 382 502 B1 discloses a USB power supply unit that provides power according to the USB-PD standard at USB-C ports and limits the power output to a maximum total power level based on a table of power profiles at the USB-C ports if this limit is exceeded. The power requirement is detected by a controller monitoring the connection and disconnection of devices to a USB-C port.

[0015] WO 2019 / 040184 A1 discloses a system with USB port management functions that allow arbitration between ports for handling power supply and power consumption.

[0016] US 2009 / 0100275 A1 discloses a method and a device for dynamically adjusting the amount of power or current distributed to one or more connected devices via electrical interfaces. The device has a first module for sensing the current drawn by a first set of ports and a second module for adjusting the current supplied to a second set of ports based on the sensed current. The second module can distribute unreserved current to the devices according to an allocation protocol. This allows a device to draw more current than needs to be reserved for it, for example, to comply with a USB specification, without increasing the total amount of power that must be allocated to the serial USB ports.

[0017] The object of the present invention is to create an improved USB connector unit and an improved method for charging control with such a USB connector unit.

[0018] The problem is solved by the USB connection unit with the features of claim 1 and the method with the features of claim 10. Advantageous embodiments are described in the dependent claims.

[0019] It is proposed that the control device be configured to measure the output current actually transferred via the USB port to the power-requiring USB connector unit and to reduce power limitations for the other USB ports of the USB connector unit when the measured output current is less than a predetermined first limit, whereby the power reserved for the USB connector unit at the USB port through which the measured output current is actually transferred is distributed among the other USB ports.

[0020] This allows a USB connector plugged into a USB port, which has an identification resistor for transmitting a power supply request to the USB connector, to be supplied with power according to its actual power requirement. If the USB connector plugged into the USB port does not require power, the power previously reserved for that USB port due to the identification resistor can be distributed among the other USB connectors.

[0021] The USB connector is thus configured to additionally measure the output current actually transmitted to a connected USB plug unit that has an identification resistor. However, the result of this current measurement only needs to be considered if the power request, i.e., the power supply demand, is not signaled via communication according to the USB-PD standard, but rather by connecting at least one identification resistor, e.g., on the CC or data line of the USB connector.

[0022] The current transferred from the USB module to the connected device can typically be measured as the voltage drop across a shunt resistor in the USB power supply line. However, other measurement methods are also possible, particularly current measurement via the magnetic field around the conductor. For this purpose, Hall sensors are available, which utilize the Hall effect to determine the magnetic field, a measure of the current flowing through the conductor. Other current measurement methods are equally applicable.

[0023] If, after detection of the power demand via at least one identification resistor, no current flow is measured that exceeds the first limit, such as a current of at least 200 mA, this connection is considered unused and the already reserved power is distributed to the other connections.

[0024] The control device can be configured to detect a connected USB plug unit to a USB port if the measured output current is greater than a second limit value.

[0025] The first limit value is preferably none, rather than the second limit value. This results in hysteresis behavior.

[0026] At least one USB port can be configured to provide power according to the USB Power Delivery standard. This allows the power request to be detected via data communication with a USB-PD compatible device.

[0027] The control device can be configured to detect a power request from a USB connector that is not compatible with the USB Power Delivery standard by measuring a characteristic identification resistance of the USB connector.

[0028] The control device can be configured to measure at least one characteristic identification resistance on the data lines or communication lines of the USB port.

[0029] The control unit can be configured to detect a power request from a USB connector compatible with the USB Power Delivery standard by communicating data with the USB connector.

[0030] At least one of the USB ports can be a connector according to the USB-C standard, which has communication line contacts (CC1, CC2), data line contacts (D+, D-), a power supply contact (VBUS) and a ground contact (GND).

[0031] The control device can have multiple control units, each designed to control at least one associated USB port.

[0032] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings. These show: Fig. 1 - Block diagram of a USB connector unit with two USB-C Power Delivery ports and two USB plug units connected to them; Fig. 2 - Block diagram of the USB connection unit Fig. 1. with an adapter cable connected to a USB port; Fig. 3 - Block diagram of the USB connection unit Fig. 1 with a USB plug unit on a first USB port and power limiting on the second USB port; Fig. 4 - Block diagram of a USB connection unit on a vehicle battery; Fig. 5 - Block diagram of the USB connection unit Fig. 1 with a powerless adapter cable as a USB plug unit on a first USB port and non-reduced power on the second USB port; Fig. 6 - Block diagram of the USB connection unit Fig. 1 with a USB plug unit on a first USB port and power limiting on the second USB port.

[0033] Fig. Figure 1 shows a block diagram of a USB connector unit 1 with two USB-C power delivery connectors 2a, 2b and two USB plug units 3a, 3b connected to them.

[0034] The USB connector unit 1 (USB module) has two USB-C ports 2a, 2b, compliant with the USB-C Power Delivery standard, with a maximum output of 45 W per port 2a, 2b. The total output is limited to 52.5 W, meaning the power must be distributed between the two ports. Each of the two USB ports 2a, 2b accepts power requests from a minimum of 7.5 W to a maximum of 45 W. Since a USB connector 3a, 3b, supporting the USB-PD standard, is connected to each port, the power is distributed according to specific algorithms and priorities. For example, 15 W could be available at the left USB port 2a and 37.5 W at the right USB port 2b.

[0035] Fig. Figure 2 shows a block diagram of the USB connector unit 1. Fig. 1 with an adapter cable as a USB plug unit 3a on a first USB port 2a.

[0036] An adapter cable is understood to be any USB connector with the possibility of connecting a USB device, such as an adapter with connectors for the USB port and the USB device to be connected with an internal cable, or a USB cable with two connectors connected via an external cable.

[0037] It is evident that an adapter cable (USB connector 3a) is plugged into the left USB port 2a, which signals a power demand of 15 W via an identification resistor 4. No communication takes place here, as the adapter cable (USB connector 3a) is purely passive. The USB connector 1 now provides 15 W of power to the left USB port 2a, regardless of whether a device is actually connected to the adapter cable (USB connector 3a) or not. The right USB port 2b is therefore limited to 37.5 W, even if the power demand of the USB connector 3b connected to the right USB port 2b is higher.

[0038] This highlights the problem that when connecting a connection unit 2a, which has an identification resistor 4 but cannot draw power, like an adapter cable (i.e., the USB port 2a is occupied without a device connected to it), power is still reserved for the connection unit 2a connected to the left USB port 2a, and thus the power distribution is not optimally balanced.

[0039] Fig. Figure 3 shows a block diagram of the USB connector unit 1. Fig. 1 with a USB connector 3a on a first USB port 2a and a power limiter on the second USB port 2b.

[0040] It is evident that a device not communicating via the USB-PD standard is connected to the left (first) USB port 2a via an adapter. A power output of 15 W is available at the left USB port 2a, which the connected USB port 3a, e.g., an earlier generation iPhone, uses to charge its battery. At this stage, the power distribution is well balanced. The left USB port 3a draws 15 W, and the right port 3b has 37.5 W available. When the battery of the left USB port 3a is nearly fully charged, the power drawn by the left USB port 3a decreases. However, USB port 3a still signals a power demand of 15 W, which USB port 1 continues to provide.When the battery is fully charged and charging is complete, the left USB port 3a no longer draws power. However, the 15W output continues to be supplied by USB port 1, while the right USB port 2b remains limited to a maximum output of 37.5W. Therefore, the power distribution is not optimal for fully utilizing the total available power of 52.5W and distributing it evenly between USB ports 2a and 2b.

[0041] Fig. Figure 4 shows a block diagram of a USB connection unit 1 with two USB ports 2a, 2b on a vehicle battery 5. The USB ports 2a, 2b each have connector sockets 6a, 6b with contacts which are each connected to the signals CC1 and CC2 for communication according to the USB-PD standard, to the data lines D+ and D- for data communication, to the power supply VBUS and to ground GND.

[0042] In the VBUS line, which supplies power to the USB connectors 3a and 3b, a shunt resistor 7a and 7b (output current sense) is installed in each case. This allows the current actually drawn by the USB connectors 3a and 3b to be determined by measuring the voltage across the resistor. Another shunt resistor 8a and 8b is located before the input of each driver stage 9a and 9b, again to determine the driver input current by measuring the voltage across the resistor 8a and 8b.

[0043] The desired voltage VBUS is generated using the illustrated driver stages 9a, 9b, each consisting of four MOSFET transistors T arranged in a full bridge configuration and an inductor L in the center of the bridge. The MOSFET transistors T of the full bridge are controlled by a control unit 10a, 10b, such as a microcontroller, which generates the four gate signals for the MOSFET transistors T. Furthermore, the control unit 10a, 10b receives a feedback signal from the generated output voltage VBUS in order to modify the gate signals in a control loop so that the desired voltage VBUS is always generated.

[0044] The two control units 10a, 10b together form a control device 10.

[0045] Both USB-PD circuits 2a, 2b with driver stages 9a, 9b and input shunt resistors 8a, 8b are filtered by a filter circuit consisting of at least one electrolytic capacitor C2 and / or an inductor L1 and / or another capacitor C1, all connected in a π configuration. This filter circuit serves to filter out interference generated by the switching of the MOSFET transistors T, preventing it from being transmitted via the supply line of the USB connector 1 and thus interfering with other devices.

[0046] The control units 10a and 10b, which generate the gate signals, each contain a microprocessor core 11. Furthermore, a Power Delivery Controller (PD Controller) 12 is integrated into the periphery of each control unit 10a and 10b. This controller communicates with the connected USB connector 3a and 3b via the CC signals (CC1 and CC2) and the data lines (D+ and D-). The PD Controller 12 can also be implemented directly in the microprocessor core 11 as a software implementation. Through communication with the connected USB connector 3a and 3b, the PD Controller 12 negotiates the voltage and current configuration and generates the gate signals according to this configuration.

[0047] Furthermore, the control units 10a, 10b contain a non-volatile memory 13 which contains at least the possible current-voltage configurations of this USB port 2a, 2b.

[0048] The control units 10a, 10b, together with the driver stage 9a, 9b, are configured to generate both an output voltage VBUS that is greater than the input voltage (battery voltage) and an output voltage VBUS that is less than the battery voltage. This is commonly known as a buck-boost converter 14.

[0049] The control units 10a, 10b, together with the shunt resistors 7a, 7b, are configured to limit the output current if the USB connector 3a, 3b connected to the respective USB port 2a, 2b draws a higher current than specified in the configuration. For this purpose, the shunt resistor 7a, 7b is connected to a current measuring unit 15, which may, for example, include an analog-to-digital converter to convert the voltage drop across the shunt resistor into a digital value that can be evaluated by the controller. The current measuring unit 15 can be integrated into the controller.

[0050] The control units 10a and 10b can limit the output current if it exceeds the current specified by the configuration. The limiting can also be set to activate only when the input current exceeds an additional tolerance value. This tolerance value can depend on other parameters, such as the input voltage, the output voltage, the temperature, or the duration of the current exceedance.

[0051] The control units 10a, 10b can be configured as CC / CV (constant current / constant voltage) for generating the gate signals. As long as the current draw is below the configured current limit, the driver stage 9a, 9b generates a constant voltage. If the load increases due to the connected device 3a, 3b and the current limit is exceeded, the voltage is reduced to a value so that only the configured current is supplied.

[0052] Furthermore, the PD controller 12 can detect whether pull-up or pull-down resistors are connected to the CC lines or the data lines if no data communication is established. In this case, a configuration is set according to the measured resistances and the corresponding power is reserved.

[0053] Both control units 10a, 10b are additionally connected to each other via further communication lines 16. They exchange information via these communication lines 16 and negotiate which control unit 10a, 10b may supply how much power to its connected USB connector 3a, 3b.

[0054] To measure the driver input current, the shunt resistors 8a, 8b are connected to a current measuring unit 17, which can be implemented as an analog-to-digital converter to measure the voltage drop across the respective shunt resistor 8a, 8b and convert it into a digital value proportional to the driver input current. The current measuring unit 17 can be integrated into the controller.

[0055] The current measuring unit 17 can be connected to a protection circuit 18, which in turn can be connected to the current measuring unit 15, the microprocessor core 11 and the buck-boost converter 14.

[0056] Fig. Figure 5 shows a block diagram of the USB connector unit 1. Fig. 1 with a powerless adapter cable as USB plug unit 3a on a first USB port 2a and an unreduced power on the second USB port 2b.

[0057] This illustrates the scenario where a USB-PD device, such as a notebook PC, is connected to the right (second) USB port 2b as a USB connector 3b, and 45 W of power is transferred via this port. Subsequently, a USB-C to Lightning adapter cable 3a is plugged into the left (first) USB port 2a. The control unit 10a detects a power demand of 15 W via the identification resistors 4 and reserves this power for this first USB port 2a. As a result, the right USB port 2b is now limited to 37.5 W to avoid exceeding the maximum available power of 52.5 W. After a short time, the left controller, i.e., the control unit 10a, detects that no power is actually being drawn and releases the reservation. Consequently, the right USB port 2b again provides the full 45 W.The right USB port 2b can even handle 52.5 W, as no power is now reserved for the left USB port 2a. The left (first) USB port 2a remains active, however, and continues to provide the 5 V supply voltage VBUS at its output.

[0058] After some time, the adapter cable (USB connector 3a) connected to the left (first) USB port 2a is connected to a mobile phone, which in Fig. 6 is shown.

[0059] This shows Fig. 6 a block diagram of the USB connection unit 1 from Fig. 1 with a USB connector 3a on the first USB port 2a and a power limiter on the second USB port 2b.

[0060] The USB connector 3a, connected to the left (first) USB port 2a, detects the voltage present at the first USB port 2a and knows that it is allowed to draw 15 W of power. As soon as the left controller, i.e., the control unit 10a, detects that a current of more than 200 mA is flowing, the control unit 10a again reserves the power of 15 W according to the power requirement of the connected first USB connector 3a, which results in the right (second) USB port 2b being limited to a power of 37.5 W again.

[0061] After some time, the USB device 3a connected to the first USB port 2a, i.e., a mobile phone, is fully charged, and the charging current drops below 200 mA. The left controller, i.e., the control unit 10a, measures an output current of less than 200 mA and releases the reserved power of 15 W. The right (second) USB port 2b can now again provide the USB device 3b connected to it with the full power of 45 W, or even the total power of 52.5 W. The left (first) USB port 2a continues to generate the output voltage VBUS of 5 V, thus maintaining a trickle charge current of less than 200 mA. The power drawn in this way, a maximum of 1 W, is not included in the power distribution balance ("power sharing balance"). The system is designed in such a way that the additional small amount of power is tolerated by the system.

[0062] In this example, the second threshold for detecting a connected USB connector 3a, 3b has been set to 200 mA. However, this first threshold can be any other suitable value. The second threshold can be configurable. To prevent excessively frequent switching between power reservation and revocation, hysteresis can be implemented. For this purpose, the first threshold for controlling power reduction can be lower than the second threshold for detecting a connected USB connector 3a, 3b. Alternatively, the second threshold for detecting a connected USB connector 3a, 3b can be divided into two parts: a lower threshold for detecting a free USB port 2a, 2b without a connected USB connector 3a, 3b, and an upper threshold for detecting an occupied USB port 2a, 2b with a connected USB connector 3a, 3b.For example, a parameterization is conceivable in which the control unit 10 detects a connected USB plug unit 3a, 3b when the current rises above 300 mA, and does not detect a connected USB plug unit 3a, 3b when the current falls below 200 mA.

[0063] As the examples show, this method of detecting a connected device has the advantage that, in some cases, the second USB port 2b can much more frequently draw its full power (e.g., 45 W) or total power (e.g., 52.5 W) instead of the reduced power (e.g., 30 W), resulting in faster charging of the notebook battery. Furthermore, the practice of leaving a USB connector (3a, 3b) plugged into the first USB port 2a, even when no device is connected, does not negatively affect the charging time of the notebook via the second USB port 2b.

[0064] The power distribution described for two USB ports 2a, 2b can be extended in a similar manner to more than two USB ports 2a, 2b. The relationships described above are therefore not limited to two USB ports 2a, 2b, but apply to any number of USB ports 2a, 2b, ..., 2n of a USB connection unit 1. Reference symbol list 1 USB port 2a, 2b USB port 3a, 3b USB connector 4 Identification resistance 5 Vehicle battery 6a, 6b connection socket 7a, 7b Shunt resistance 8a, 8b Shunt resistance 9a, 9b Driver stage 10 Control unit 10a, 10b Control unit 11 microprocessor cores 12 Power Delivery Controllers (PD Controllers) 13 storage locations 14 Buck-Boost Converters 15 current measuring unit 16 Communications Management 17 Current measuring unit 18 Protection circuit C1 Capacitor C2 electrolytic capacitor CC1, CC2 communication signals D+, D data line GND Ground L1 coil L coil T MOSFET transistor VBUS power supply

Claims

[1] USB connection unit (1) with a control unit (10) and with at least two USB ports (2a, 2b) connected to the control unit (10), wherein the control unit (10) is configured to detect a power supply request from a USB plug unit (3a, 3b) connected to a USB port (2a, 2b), characterized by, that the control device (10) is configured to measure the output current actually transferred via the USB port (2a, 2b) to the power-requiring USB connector unit (3a, 3b) and to reduce power limitations for the other USB ports (2a, 2b) of the USB connector unit (1) when the measured output current is less than a predetermined first limit, wherein the power reserved for the USB connector unit (3a, 3b) at the USB port (2a, 2b) through which the measured output current is actually transferred is distributed among the other USB ports (2a, 2b). [2] USB connection unit (1) according to claim 1, characterized by , that the control device (10) is set up to detect the connection of a connected USB plug unit (3a, 3b) to a USB port (2a, 2b) when the measured output current is greater than a second limit value. [3] USB connection unit (1) according to claim 2, characterized by that the first limit is smaller than the second limit. [4] USB connection unit (1) according to any one of claims 1 to 3, characterized by , that at least one USB port (2a, 2b) is set up to provide power according to the USB Power Delivery standard. [5] USB connection unit (1) according to any one of the preceding claims, characterized by , that the control device (10) is configured to detect a power request from a USB connector (3a, 3b) that is not compatible with the USB Power Delivery Standard by measuring at least one characteristic identification resistance (4) of the USB connector (3a, 3b). [6] USB connection unit (1) according to claim 5, characterized by, that the control device (10) is set up to measure the at least one characteristic identification resistance (4) on the data lines (D+, D-) or communication lines (CC1, CC2) of the USB connector (2a, 2b). [7] USB connection unit (1) according to any one of the preceding claims, characterized by , that the control device (10) is set up to detect a power request from a USB connector (3a, 3b) compatible with the USB Power Delivery Standard by means of data communication with the USB connector (3a, 3b). [8] USB connection unit (1) according to any one of the preceding claims, characterized by , that at least one of the USB ports (2a, 2b) is a connector according to the USB-C standard comprising communication line contacts (CC1, CC2), data line contacts (D+, D-), a power supply contact (V BUS ) and a ground contact (GND). [9] USB connection unit (1) according to any one of the preceding claims, characterized by , that the control device (10) has several control units (10a, 10b) each designed to control at least one associated USB port (2a, 2b). [10] Method for charging control of a USB connection unit (1) according to one of the preceding claims, characterized by Measuring the output current actually transferred via the USB port (2a, 2b) to the power-requiring USB connector (3a, 3b) and reducing power limits for the other USB ports (2a, 2b) of the USB connector unit (1) when the measured output current is less than a predetermined first limit, whereby the power reserved for the USB connector unit (3a, 3b) at the USB port (2a, 2b) through which the measured output current is actually transferred is distributed to the other USB ports (2a, 2b). [11] Method according to claim 10, characterized by Detect a USB plug unit (3a, 3b) connected to a USB port (2a, 2b) when the measured output current is greater than a second limit value, where the first limit value is less than the second limit value. [12] Method according to claim 10 or 11, characterized by Detecting a power request from a USB connector (3a, 3b) not compliant with the USB Power Delivery standard by measuring at least one characteristic identification resistance (4) of the USB connector (3a, 3b) and detecting a power request from a USB connector (3a, 3b) compliant with the USB Power Delivery standard by data communication with the USB connector (3a, 3b).

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