Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J1/00—Circuit arrangements for DC mains or DC distribution networks
  • H02J1/14—Balancing the load in a network
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries

Definitions

• the present invention relates generally to USB chargers. More specifically, the present invention relates to a USB charging system that is capable of outputs through multiple universal serial buses to charge one or more electronic devices.
• the electrical energy is generally provided by a battery enclosed within the electronic device.
• the battery may be a disposable battery but more commonly, it is a rechargeable battery.
• the rechargeable battery must be recharged with a direct current source when it is depleted.
• USB Universal serial bus
• the rechargeable battery in an electronic device is recharged by electrically connecting it to the direct current output of the charger or the USB port.
• a standard USB port is capable of supplying 1 A at 5V for a total power of 5W.
• Apple USB charge specification for iPad, iPod, and iPhone specifies that a resistor network be placed on the USB D+ and D- data lines. This network tells the device what current is available from the USB power source.
• resistor network is setup such that Rl is 43.2k, R2 is 49.9k, R3 is 75k, and R4 is 49.9k then the iPad will charge at 2.1 A maximum. If Rl is 75k, R2 is 49.9k, R3 is 43.2k, and R4 is 49.9k then it will charge at 1 A max.
• These resistors can be present on the D+/- signals of a USB connector or can be placed directly on the 30 pin dock instead.
• Electronic devices such as the iPod and iPhone only require 1 A to efficiently charge their battery. However, an iPad requires 2.1 A to efficiently charge its battery.
• the present invention is a dual output power USB charging system that can charge at 2.1 A and also at 1 A at the same time when the power supply is only capable of 10W.
• a USB port is set as a 2.1 A Apple port via resistor network. If nothing is connected to the other USB port, it charges the iPad at 2.1 A. If a device is connected to the other USB port, it automatically detects this condition and momentarily interrupts the 5 V output while resetting the USB port to 1 A (Apple resistor network is changed to 1A spec). Both devices will then charge at 1 A. If the second device is disconnected while the iPad is still charging at 1 A, the charging system will interrupt the output momentarily and reset the Apple network back to 2.1 A.
• the iPad re-registers and is now able to charge at 2.1 A again. If the USB device is connected first while the USB port is unused it will also set both ports as 1 A. As the standard USB port is switched between 1 A and 2.1 A Apple network, the current limit is also automatically switched from lA to 2.1 A.
• Figure 1 shows the circuit for the USB charging system using the analog method.
• Figure 2 shows the circuit for the USB charging system using the analog method with the preferred values for the circuit components.
• FIG. 3 shows the circuit for the USB charging system using the MCU controlled method.
• FIG. 4 shows the circuit for the USB charging system using the MCU controlled method with the preferred values for the circuit components.
• Figure 5 shows the preferred embodiment of an AC/DC power source with the preferred values for the circuit components.
• This invention allows a 10W supply to support two iPads or an iPad and an iPod or iPhone allowing each device to charge at a predictable current. For example, if a single iPad is connected to USB port #1 , the resistor network will be set at 2.1 A and the iPad will charge at 2.1 A max. If another device (iPad, iPod, or iPhone) is connected to USB port #2, then both USB port resistor networks will be changed from 2.1 A to 1A allowing each device to charge at 1 A. To do this the power supply must interrupt its output before changing the networks to allow the original iPad to 're-register' the new charge condition. The default condition, without any devices connected, sets each port to 2.1 A resistor network. For the invention to operate, it must detect the presence of two devices. It can do this task in two ways.
• the standard Apple USB to dock connector cable includes a wire that connects the USB metal frame to the dock connector metal frame.
• the Apple device When the Apple device is connected to the dock connector its internal power ground signal is shorted to the frame, which in turn makes the USB frame also ground. If the corresponding frame contact on the USB port is pulled up by a resistor to +5V, then the signal labeled SI goes from +5V to 0V when the Apple device is connected. The same applies to the second port and the signal S2.
• each port is setup per the 2.1 A specification.
• S 1 and S2 are both +5V.
• the signal /2A is set to 0. This turns on Q2 via R8, which shorts out R21.
• the resistance from D1+ to +5V becomes 43.2k Ohms.
• D2+/- networks The same applies to D2+/- networks.
• the above method also applies to the case where an iPad is connected to one port and a non- Apple device (such as a smartphone or an Android tablet) is connected to the other port.
• a non- Apple device such as a smartphone or an Android tablet
• the two port condition will be detected and the iPad will be charged at 1A instead of 2.1A.
• Another embodiment is the MCU controlled method shown in figures 3 and 4. This method uses a microcontroller to detect the presence of two devices and does not require the use of a grounded frame cable.
• the basic procedure is the same as in the analog method.
• the system defaults with 2.1 A resistor network in each USB port.
• the behavior of the /2A signal is the same.
• the difference in this method is how the MCU (U2) detects the presence of the device connected to each USB port.
• Two MCU A/D inputs (pins 19 and 20) monitor the voltage change of Dl - and D2- signals.
• Dl - and D2- are biased at +2.7V by the resistor networks.
• Dl - and D2- are biased at +2.7V by the resistor networks.
• the MCU sets the /2A signal high setting both ports to 1 A.
• the MCU also sets PWROFF momentarily high to interrupt the USB +5V output.
• the MCU reads the D- voltage change, interrupts power once again, and resets the networks to 2.1 A.
• Both embodiments above use a DC/DC +5V supply as the power source.
• This supply can also be an AC/DC power source shown in figure 5.
• the power on/off control is done by a power FET transistor connected to the USB power lines of both USB ports.
• the FET circuit can be used in both Analog and MCU methods.
• the PWROFF signal is +5V. This turns on Q3, which in turn sets the FET get low shorting the source (S) to the drain (D). This applies power to both USB ports.
• PWROFF goes low, Q3 is turned off which turns off the FET and power is removed from the USB ports.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Power Sources (AREA)

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Cited By (5)

Citations (6)

• 2012
  • 2012-09-28 WO PCT/US2012/057842 patent/WO2014051610A1/fr not_active Ceased

Patent Citations (6)

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