Abstract:
An electronic device includes a universal serial bus (USB) interface therein. This USB interface is configured to support at least first and second different USB interface standards. These different interface standards are selected by the electronic device in response to comparing a voltage level of a signal provided to said USB interface relative to a reference voltage generated within the electronic device. The signal provided to the USB may be a power supply signal, the first USB standard may be a USB 2.0 interface standard and the second USB standard may be an inter-chip USB interface standard.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/751,104, filed May 21, 2007 now U.S. Pat. No. 7,769,914, which claims priority to Korean Patent Application No. 10-2006-048944, filed May 30, 2006, the disclosures of which are hereby incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to devices having USB interfaces therein and methods of operating the USB interfaces. 
     BACKGROUND OF THE INVENTION 
     Universal Serial Bus (USB) technology is widely used for communicating data between a computer system and a peripheral device. The USB technology provides interface standardization for connecting peripheral devices, such as a mouse, a printer, a modem, or a speaker with computers. The USB is a type of a serial port supported by a consortium of personal computer manufactures, such as Intel, Compaq, Microsoft, Philips, IBM, and NEC. 
     The full speeds of a serial port and a USB port are 100 Kbps and 12 Mbps, respectively, for data transmission. Accordingly, various devices may be connected through the USB port without speed limitation. When a computer is in use and peripheral devices are connected through the USB port, the connections are automatically recognized. The peripheral devices connected through the USB port do not need to have internal power supplies. The reason is that power is supplied from a USB host. For example, peripheral devices can connect to a USB host such as a computer through the same USB port without additional software or hardware. Therefore, the number of ports can be drastically reduced. Accordingly, the size of electronic devices, such as a portable terminal, can be minimized. 
     According to a USB standard, the two terminals connected through a USB port are a host and a USB device, respectively. The host controls the topology management of a bus, the monitoring of a USB device state, device control, and data transmission management through a bus, and supplies a predetermined operating voltage (i.e., a power supply voltage VDD) to the USB device. 
     As described above, most computers include a USB port such that it is unnecessary to install complex and various adaptors. When data is transferred from a mobile phone or a digital camera to a computer, the USB port is widely used. Due to this convenience of a USB port, terminals connected according to a USB standard (i.e., a USB interface standard) become more extensively used in different applications. That is, the USB standard is utilized to support an external communication between individual terminals, such as a mobile phone or a personal computer, and also to support internal communication (i.e., a local communication) between chips integrated in one system. Accordingly, different USB standards are set depending on application (i.e., according to an external communication between individual devices and an internal communication between chips). In this case, a new USB device is in demand, which performs communication according to different USB standards through one port. Thus, it is necessary to develop a new USB device capable of performing communication in different USB interface standards according to various hosts. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention include an electronic device having a universal serial bus (USB) interface therein. This USB interface is configured to support at least first and second different USB interface standards. These different interface standards are selected by the electronic device in response to comparing a voltage level of a signal provided to said USB interface relative to a reference voltage generated within the electronic device. In some of these embodiments, the signal provided to the USB is a power supply signal, the first USB standard is a USB 2.0 interface standard and the second USB standard is an inter-chip USB interface standard. 
     According to additional embodiments of the invention, an electronic device having a universal serial bus (USB) interface is provided. This electronic device includes first and second input/output terminals and first and second transceivers electrically connected to the first and second input/output terminals, respectively. An interface controller is also provided within the electronic device. The interface controller, which is electrically coupled to the first and second transceivers, is configured to transmit and receive first data signals to and from the first transceiver according to a first USB standard (e.g., USB 2.0 interface standard) and is further configured to transmit and receive second data signals to and from the second transceiver according to a second USB standard (e.g., inter-chip USB interface standard). 
     The electronic device may also include a voltage detector. This voltage detector (e.g., comparator) may be configured to generate a voltage detection signal (V DET , V COM ) in response to comparing a voltage level of a reference signal generated within the electronic device against a voltage level of a signal received at the USB interface. In some embodiments of the invention, the signal received at the USB interface is a power supply voltage. In other embodiments of the invention, the signal received at the USB interface is a signal received at the first input/output terminal. The interface controller, which is responsive to the voltage detection signal, changes configuration between transmitting and receiving to the first transceiver according to the first USB standard and transmitting and receiving to the second transceiver according to the second USB standard, in response to detecting changes in a level of the voltage detection signal. In particular, the interface controller may include a switching device that is responsive to the voltage detection signal and has first and second input terminals electrically coupled to the first and second transceivers, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a system having USB transmission components therein. 
         FIG. 2  is a block diagram of a system with a USB interface according to one embodiment of the present invention. 
         FIG. 3  is a block diagram of a system with a USB interface, according to another embodiment of the present invention. 
         FIG. 4  is a block diagram of a system with a USB interface according to further embodiments of the present invention. 
         FIG. 5  is a perspective view of a USB host and a USB device according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout. 
       FIG. 1  is a block diagram of a USB transmission line. Referring to  FIG. 1 , a USB connection between a host  10  and a USB device  20  includes four signal lines  31  through  34 . A VDD line  31  (i.e., a power supply line), and a GND line  34  are lines supplying a power from the host  10  into the USB device  20 . A D+/DP line  32  and a D−/DM line  33  are lines that support serial data communication between the host  10  and the USB device  20 . A USB standard for performing communication according to USB Spec. Revision 2.0 is called a “USB 2.0 interface”. A USB standard for performing communication within a range of 5 to 10 cm is called an “Inter-Chip USB (IC-USB) interface”. A pair of complementary data signals are transmitted onto D+ and D− signal lines by using a USB 2.0 standard, and a pair of complementary data signals are transmitted onto DP and DM signal lines by using an IC-USB standard. 
       FIG. 2  is a block diagram of a USB device according to one embodiment of the present invention. Referring to  FIG. 2 , a USB host  100  includes a pad  110  for transmitting and receiving a data signal D+/DP, a pad  120  for transmitting and receiving a data signal D−/DM, and a power supply pad  130  for supplying a power supply voltage VDD. A ground pad (not shown) is also provided for supplying a ground signal (GND) to a ground line (not shown) (see, e.g.,  FIG. 1 ). For example, when the USB host  100  utilizes the IC-USB interface for local communication, it transmits and receives the data signals DP and DM. On the other hand, when the USB host  100  utilizes the USB 2.0 interface, it transmits and receives data signals D+ and D−. 
     The USB device  200  includes first and second pads  210  and  220 , a power pad  230 , first to fourth transceivers  212 ,  214 ,  222 , and  224 , a voltage detector  240 , a reference voltage generator  242 , and an interface controller  252 . The first pad  210  is an I/O pad for transmitting and receiving the data signal D+/DP, and the second pad  220  is an I/O pad for transmitting the data signal D−/DM. Additionally, the power pad  230  is a pad for receiving the power supply voltage VDD from the host  100 . 
     The interface controller  252  includes a switching unit having two switches  216  and  226  and a controller  250 . The interface controller  252  activates first to fourth data paths, and controls a signal exchange with the host  100 . The first and second data paths are connected to the first pad  210 . The first data path includes a first transceiver  212  connected to the first pad  210 , and the second data path includes a second transceiver  214  connected to the first pad  210 . The first transceiver  212  transmits and receives a data signal D+, and includes an input/output buffer (not shown) and driver (not shown) according to the USB 2.0 interface. The second transceiver  214  transmits and receives a data signal DP, and includes an input/output buffer (not shown) and driver (not shown) according to the IC-USB interface. 
     The third data path includes a third transceiver  222  connected to the second pad  220 , and a fourth data path includes a fourth transceiver  224  connected to the second pad  220 . The third transceiver  222  transmits and receives a data signal D−, and includes an input/output buffer (not shown) and driver (not shown) according to the USB 2.0 interface. The fourth transceiver  224  transmits and receives a data signal DM, and includes an input/output buffer (not shown) and driver (not shown) according to the IC-USB interface. 
     First to fourth data paths include a data input line and a data output line, respectively. Each of the data input lines is connected to input terminals of the switches  216  and  226  through the pads  210  and  220  and the transceivers  212 ,  214 ,  222 , and  224 . Each of the data output lines is connected to the pads  210  and  220  through a controller  250 , switches  216  and  226 , and transceivers  212 ,  214 ,  222 , and  224 . 
     On the other hand, the first pad  210 , as illustrated in  FIG. 2 , has a structure in which two pads  211  and  213  are connected in a double bonding arrangement to a transmission line  32 ′. Additionally, the second pad  220  has a structure in which two pads  221  and  223  are connected in a double bonding arrangement to a transmission line  33 ′. In this case, the pads  211 ,  213 ,  221 , and  223  are connected to the first to fourth transceivers, respectively. 
     Received data output lines of the transceivers  212  and  214  are connected to input terminals of the first switch  216 . The output terminal of the first switch  216  is connected to a controller  250 . That is, receive signals RX_D+ and RX_DP input into the first pad  210  are input to the first switch  216  through the transceivers  212  and  214  of the first and second data paths. The first switch  216  selects one of the receive signals RX_D+ and RX_DP and outputs the selected one into the controller  250 . Likewise, the received data output lines of the transceivers  222  and  224  are connected to input terminals of the second switch  216 , and the output terminal of the second switch  226  is connected to the controller  250 . That is, the receive signals RX_D− and RX_DM input into the second data pad  220  are input into the second switch  226  through the transceivers  222  and  224  of the third and fourth data paths, and the second switch  226  selects one of receive signals RX_D+ and RX_DP and then outputs the selected one into the controller  250 . 
     The power pad  230  is connected to a voltage detector  240  and a reference voltage generator  242 , respectively. The voltage detector  240  compares a power supply voltage VDD input into the power pad  230  with a reference voltage Vref outputted from the reference voltage generator  242 . The voltage detector  240  delivers an output signal Vdet (i.e., the compared result), into the switches  216  and  226 , and the controller  250 . 
     The first switch  216  connects one of the input lines in the first and second data paths to the controller  250  in response to the output signal Vdet of the voltage detector  240 . That is, the first switch  216  delivers the receive signal RX_D+ outputted from the first transceivers  212  into the controller  250  or delivers the receive signal RX_DP outputted from the second transceivers into the controller  250  in response to the output signal Vdet of the voltage detector  240 . Likewise, the second switch  226  connects one of the input lines in the third or fourth data paths to the controller  250  in response to the output signal Vdet of the voltage detector  240 . That is, the second switch  26  delivers the receive signal RX_D− outputted from the third transceiver  222  into the controller  250  or delivers the receive signal RX_DM outputted from the fourth transceiver into the controller  250  in response to the output signal Vdet of the voltage detector  240 . 
     The controller  250  processes the receive signals RX_D+ and RX_D− input according to the USB 2.0 method or the receive signals RX_DP and RX_DM input according to the IC-USB method. Additionally, the controller  250  activates one of the output lines in the first and third data paths, and also activates one of the output lines in the second and fourth data paths according to the output signal Vdet of the voltage detector  240 . That is, according to the detected result of the voltage detector  240 , the controller  250  outputs the transmitted and receive signals TX_D+ and TX_D− into the transceivers  212  and  222  that transmit signals through the USB 2.0 interface or outputs the transmitted and receive signals RX_DP and TX_DM into the transceivers  214  and  224  that transmit signals through the IC-USB interface. 
     For example, when the USB host  100  transmits signals according to the USB 2.0 interface, it transmits data signals onto D+/DP and D−/DM transmission lines  32 ′ and  33 ′ according to a USB 2.0 protocol. The signals input onto the D+/DP transmission lines  32 ′ are input into the transceivers  212  and  214  through the first pad  210  of the USB device  200 . As described above, the transceivers  212  and  222  have a structure according to the USB 2.0 interface, and the transceivers  214  and  224  have a structure according to the IC-USB interface. The transceivers  212 ,  214 ,  222 , and  224  output the receive signals RX_D+, RX_D, RX_DP, and RX_DM into the switches  216  and  226 . 
     On the other hand, if the USB host  100  transmits data signals and supplies a power supply voltage VDD into a VDD line  31 ′ at the same time, then the power supply voltage VDD is delivered into the voltage detector  240  and the reference voltage generator  242  through the power pad  230  of the USB device  200 . The power supply voltage VDD input through the power pad  230  is supplied to a regulator (not shown) inside the USB device  200 . The regulator converts the power supply voltage VDD into an internal operating voltage of the USB device  200  and then supplies the internal operating voltage into various internal devices (e.g., controller  250  and transceivers  212 ,  214 ,  222 , and  224 ). In this case, the controller  250  includes an additional regulator therein. 
     The voltage detector  240  compares the reference voltage Vref outputted from the reference voltage generator  242  with the power supply voltage VDD. The reference voltage Vref may be between 3.6 V and 4.5 V. In the USB 2.0 standard operating procedure, the host  100  supplies a power supply voltage in a range of 4.5 to 5.5 V. In the IC-USB standard operating procedure, the host  100  supplies a power supply voltage in a range of 2.7 to 3.6 V. Accordingly, when using a voltage of 3.6 to 4.5 V as a reference voltage Vref, it can be determined that the USB host  100  transmits a signal according to the USB 2.0 standard or not. 
     The voltage detector  240  generates a signal of a first level (e.g., a high level) when the power supply voltage VDD is higher than the reference voltage Vref, and generates a signal of a second level (e.g., a low level) when the power supply voltage VDD is lower then the reference voltage Vref. The voltage detector  240  delivers the detect signal Vdet into the switches  216  and  226  and the controller  250 . 
     The first switch  216  connects the receiving line of the first transceiver  212  to the controller  250  in response to the detect signal Vdet of a first level. That is, the first switch  216  outputs a signal RX_D+ outputted from the first transceiver  212  into the controller  250  in response to the detect signal Vdet of a first level. Additionally, the second switch  226  outputs a signal RX_D− outputted from the third transceiver  222  into the controller  250  in response to the detect signal Vdet of a first level. 
     The controller  250  processes the receive signals RX_D+ and RX_D−. For example, the controller  250  encodes a command from the host  100  to perform corresponding operations such as a data storing operation. Additionally, the controller generates transmit signals TX_D+ and TX_D− that will be transmitted to the USB host  100  and then outputs the signals into the transceivers  212  and  222 . In this case, the controller  250  selectively activates only the transmitting lines of the transceivers  212  and  222  according to the detect signal Vdet outputted from the voltage detector  240 . That is, the controller  250  activates the output drivers of the transceivers  212  and  222  transmitting the signals through the USB 2.0 interface, and then transmits the transmit signals TX_D+ and TX_D− into the transceivers  212  and  222  through the switches  216  and  226 . In this case, the switches  216  and  226  output the transmit signals TX_D+ and TX_D− into the transceivers  212  and  222  in response to the detect signal Vdet from the voltage detector  240 . The transceivers  212  and  222  then output the transmit signals into the first and second pads  210  and  222 , respectively. 
     Hereinafter, when the host  100  transmits a signal according to the IC-USB standard, the operations of the USB device  200  are identical to the above except for the following operation. Since the operating voltage VDD according to the IC-USB standard is below 2.7 to 3.6 V, the voltage detector  240  outputs the detect signal Vdet at the second level. Accordingly, the switches  216  and  226  connect the receiving lines of the transceivers  214  and  224  to the controller  250  according to the IC-USB interface. That is, the switches  216  and  226  transmit the receive signals RX_DP and RX_DM, which are respectively outputted from the transceivers  214  and  224 , to the controller  250 . When transmitting the transmit signals to the host  100 , the controller  250  enables only the transmitting line (outputting drive) using the transceivers  214  and  224  in the IC-USB interface according to the detect signal Vdet of the voltage detector  240 . The controller  250  outputs the transmit signals TX_DP and TX-DM to the transceivers  214  and  224  through the switches  216  and  226 . 
       FIG. 3  is a block diagram of a USB device  300  according to another embodiment of the present invention. The USB device  300  of  FIG. 3  is identical to the USB device  200  of  FIG. 2  except for a reference voltage generator  342  and a comparator  340 . The USB device  300  will be described as follows. Referring to  FIG. 3 , the reference voltage generator  342  receives a signal input into a second pad  220  to generate a reference voltage Vref′. A comparator  340  compares the reference voltage Vref′ with a power supply voltage VDD to generate a result signal Vcom. For example, the comparator  340  generates a signal of a first level when the reference voltage Vref′ is unequal from the power supply voltage VDD, and generates a signal at a second level when the reference voltage Vref′ is equal to the power supply voltage VDD. In this case, the reference voltage generator  342  generates a voltage as the reference voltage Vref′. The voltage is identical to a high level voltage among data signals outputted from the USB host  200 . As shown in  FIG. 3 , the data signals input into the second pad  220  is delivered into the reference voltage generator  342 . Alternatively, the data signal input into the first pad  210  may be delivered into the reference voltage generator  342 . 
     According to the USB 2.0 standard, the power supply voltage VDD is in a 5 V region (4.5 to 5.5 V), and a high level of the data signal is in a 3 V region (2.7 to 3.6 V). On the other hand, according to the IC-USB standard, the power supply voltage VDD and a high level (i.e., a reference voltage Vref) of the data signal have the same voltage region (1.8 V or 3V). Accordingly, when the power supply voltage VDD is different from the high level (i.e., a reference voltage Vref′) of the data signal, it is determined that the host includes the USB 2.0 interface. When the power supply voltage VDD is identical to the high level (i.e., a reference voltage Vref′) of the data signal, it is determined that the host includes the IC-USB interface. 
       FIG. 4  is a block diagram of a USB device according to further embodiment of the present invention. The USB device  400  of  FIG. 4  is identical to that of  FIG. 3  except for controllers  450  and  450 ′. Referring to  FIG. 4 , the USB device  400  includes two controllers  450  and  450 ′. The first controller  450  processes signals according to the USB 2.0 standard, and the second controller  450 ′ processes signals according to the IC-USB standard. When there are the two controllers separated from each other according to the USB standard, efficiency of processing signals can be improved. For example, when only one controller is used, an operation of initializing (or, resetting) a signal processing procedure is required when processing receive signals according to the IC-USB standard after processing the receive signals according to the USB 2.0 standard. When there are two separate controllers, each of the controllers processes different signals, thereby directly processing input signals without an initializing (or, resetting) operation. 
       FIG. 5  is a view of a USB host and a USB device according to an embodiment of the present invention. Referring to  FIG. 5 , the USB hosts includes a computer system  1000  and a portable communication terminal  1000 ′. The computer system  1000  includes a USB port  1100  using a USB 2.0 interface. The portable communication terminal  1000 ′ includes a USB port  1100 ′ using an IC-USB interface. For example, the USB device  2000  includes a SIM card. The SIM card is a Subscriber Identification Module card. The SIM card  2000  includes a connection unit  2100  that can be electrically connected to USB ports  1100  and  1100 ′, and is compatible with the USB 2.0 and IC-USB interfaces. That is, when the SIM card  2000  is inserted into the portable communication terminal  1000 ′, it uses the IC-USB interface. When the SIM card  2000  is inserted into the personal computer, it uses the USB 2.0 interface through a USB port. Accordingly, a user takes advantage of a dual interface without adding an additional port or connector. 
     In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.