Abstract:
A smart card that may include a first interface circuit to perform a first type interface with the outside using first and second pads; a second interface circuit to perform a second type interface with the outside using the first and second pads; and a mode selector to enable one of the first and second interface circuits according to whether a power supply voltage is supplied through a third pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2010-0073618, filed on Jul. 29, 2010, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present inventive concept herein relates to a smart card and an interface method thereof. 
     2. Description of the Related Art 
     A “smart card” refers to a card into which an integrated circuit is inserted, and the integrated circuit may comprise a microprocessor, a card operating system, a security module, a memory, etc. A smart card module inserted into most of the smart cards includes a printed circuit board (PCB) on which an integrated circuit chip is mounted. One side of the printed circuit board (PCB) includes an integrated circuit chip and the other side of the printed circuit board (PCB) includes eight electrical contacts according to the international organization for standardization (ISO) 7816. 
     As uses of a smart card have been diversified, a need for a communication with a host using various interfaces is increasing. Thus, a development of a smart card that can support various interfaces through the limited eight electrical contacts is required. 
     SUMMARY OF THE INVENTION 
     Embodiments of the inventive concept provide a smart card. 
     Additional aspects and advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept. 
     In exemplary embodiments of the present inventive concept, the smart card may include a first pad; a second pad; a third pad being supplied with a power supply voltage; a first interface circuit to perform a first type interface with the outside using the first and second pads; a second interface circuit to perform a second type interface with the outside using the first and second pads; and a mode selector enabling one of the first and second interface circuits according to whether or not the power supply voltage is supplied through the third pad. 
     Embodiments of the inventive concept also provide a smart card that may include a first pad that can be connected to a host; a second pad that can be connected to the host; a third pad being supplied with a power supply voltage; an internal circuit block; and an interface module to perform an interface between the host and the internal circuit block using the first and second pads, wherein the interface module performs an interface with the host in one of the first and second type interfaces according to whether the power supply voltage is supplied through the third pad. 
     Embodiments of the inventive concept also provide an interface method of the interface module in a smart card including a plurality of pads, an interface module and an internal circuit block. The interface method may include determining whether a power supply voltage is supplied through a power supply pad; performing a first type interface between the outside and the internal circuit block using first and second pads when the power supply voltage is supplied through the power supply pad; and performing a second type interface between the outside and the internal circuit block using the first and second pads when the power supply voltage is not supplied through the power supply pad. 
     Embodiments of the inventive concept also provide a smart card including an interface module including a first interface unit to perform a first type of interface externally using a first set of contact pads to transmit data to a host by wire and wirelessly, and a second interface unit to perform a second type of interface externally using the first set of contact pads; a power supply voltage pad to receive power for an external host; and a mode selector to determine whether to enable the first or second interface unit according to whether power is supplied to the power supply voltage pad. 
     In an embodiment, the first interface unit is a USB mode interface and the second interface unit is a contactless mode interface. 
     In an embodiment, the mode selector enables the first interface unit when power is supplied to the power supply pad, and enables the second interface unit when power is not supplied to the power supply pad. 
     In an embodiment, if the mode selector determines that power is supplied to the power supply pad, and a signal received through the first set of contact pads is not suitable to the USB standard, then the mode selector disables the first interface unit and the second interface unit and operates in a serial input output (SIO) mode. 
     In an embodiment, the smart card further includes fourth through sixth pads; and a third interface unit to perform a third type interface externally using the fourth through sixth pads, wherein the mode selector disables the first and second interface units when the power supply voltage is supplied through the third pad and a signal suitable for the USB standard is not received through the first set of contact pads. 
     Embodiments of the inventive concept also provide a method of interfacing a smart card having a plurality of pads, an interface module and an internal circuit block, the method including: switching between a first type interface between the internal circuit block and an external device and a second type interface between the internal circuit block and an external device according to a determination of whether a power supply voltage is being supplied through a power supply pad. 
     In an embodiment, the method may further include switching to a third type interface when it is determined that a power supply voltage is being supplied through a power supply pad while a predetermined signal is determined not to be suitable for the first or second type interface. 
     In an embodiment, the predetermined signal is a signal suitable for a USB standard, and the third type interface is a serial input output (SIO) interface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a drawing illustrating a smart card in accordance with exemplary embodiments of the inventive concept and electronic devices that can be connected to the smart card. 
         FIG. 2  is a block diagram illustrating a constitution of the smart card illustrated in  FIG. 1 . 
         FIG. 3  is a flow chart illustrating an operation sequence of a smart card in accordance with exemplary embodiments of the inventive concept. 
         FIG. 4  is a drawing illustrating a smart card module in accordance with exemplary embodiments of the inventive concept. 
         FIG. 5  is a drawing illustrating a smart card module in accordance with other exemplary embodiments of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the inventive concept will be described below in more detail with reference to the accompanying drawings. The embodiments of the inventive concept 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 inventive concept to those skilled in the art. Like numbers refer to like elements throughout. 
     A smart card may be classified into a contact type card and a contactless type card, and there are a combination card and a hybrid card such that a contact type card and a contactless type card are combined. A contact type card must be inserted into the card reader and receives a power and a clock signal that are needed to operate a chip by a physical contact through an insertion. A contact type card has a large amount of transmitting data as compared with a contactless type card and follows the international organization for standardization (ISO) 7816. On the other hand, a contactless type card operates at a distance without being inserted into the card reader and follows the international organization for standardization (ISO) 10536 and the international organization for standardization (ISO) 14443. 
     According to an interface method provided in the international organization for standardization (ISO) 7816, the number of contact pads of a smart card is eight. A function of each of the contact pads (C 1 -C 8 ) is defined in a table 1 as follows. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 PIN # 
                 Assignment 
               
               
                   
                   
               
             
             
               
                   
                 C1 
                 VDD 
               
               
                   
                 C2 
                 RESET 
               
               
                   
                 C3 
                 CLOCK 
               
               
                   
                 C4 
                 RESERVED 
               
               
                   
                 C5 
                 VSS 
               
               
                   
                 C6 
                 VPP 
               
               
                   
                 C7 
                 I/O 
               
               
                   
                 C8 
                 RESERVED 
               
               
                   
                   
               
             
          
         
       
     
     Referring to table 1, a contact pad C 1  is used to receive a power needed for a smart card from an external host. A contact pad C 2  is used to receive a reset signal resetting an internal circuit of a smart card. A contact pad C 3  is used to receive a clock from a host. The clock is used to drive a microprocessor built in a smart card. A contact pad C 5  is used to provide an electrical ground between a host and a smart card. A contact pad C 6  may be used as a power supply pin (VPP) to program an electrically erasable programmable read only memory (EEPROM) built in a smart card. A contact pad C 7  is used when a smart card inputs and outputs data using a half-duplex method. Contact pads C 4  and C 8  are contact pads that are not defined in the international organization for standardization (ISO) 7816 yet and are spare pads to be used in the future. 
     According to an interface method provided in the international organization for standardization (ISO) 14443 that is a standard of contactless type cards, a smart card must include an antenna to communicate with a host and needs at least two pads that can be connected to the antenna. 
     The contact pads C 4  and C 8  that are not defined in the international organization for standardization (ISO) 7816 yet are only needed to be assigned as a pad to connect a smart card to an antenna in order for one smart card to support a contact mode in accordance with the international organization for standardization (ISO) 7816 and a contactless mode in accordance with the international organization for standardization (ISO) 14443. 
     The international organization for standardization (ISO) 7816 may provide a data transmission speed of 9600 bps, 19200 bps and 38400 bps. The international organization for standardization (ISO) 7816 may be mainly used in an application field that needs a narrow communication bandwidth such as an automated teller machine (ATM) or a position certifying machine. However, as an e-commerce technology using an Internet or a cell phone is developed and a requirement for a real time software encryption and for transmission and reception of huge amounts of data such as an audio file and a video file increases, a smart card requiring a wide communication bandwidth is being emphasized. 
     A universal serial bus (USB) supports a data transmission speed of 480 Mbps or 5 Gbps using a power supply voltage line, a ground voltage line and two data lines. However, contact pads for a transmission of two data signals are needed besides the power supply voltage and the ground voltage in order for a smart card to support a USB interface. 
     The present inventive concept provides a smart card that can support not only the contact type mode of the international organization for standardization (ISO) 7816 and the contactless type mode of the international organization for standardization (ISO) 14443, but also the USB mode using the limited number of contact modes. 
       FIG. 1  is a drawing illustrating a smart card in accordance with exemplary embodiments of the inventive concept and electronic devices that can be connected to the smart card. 
     Referring to  FIG. 1 , a smart card  100  can communicate with a host in a contact mode, a contactless mode form or combinations thereof. For example, the smart card  100  can communicate with a payment terminal  110  in a contactless interface mode in accordance with the international organization for standardization (ISO) 10536 and the international organization for standardization (ISO) 14443. The smart card  100  can communicate with an electronic toll collection system  120  in a contact interface mode provided in the international organization for standardization (ISO) 7816. The smart card  100  can communicate with a computer system  140  in a USB interface mode through a dongle  130 . The smart card  100  can communicate with various hosts in a contact mode and a contactless mode form besides a payment terminal  110 , the electronic toll collection system  120  and the computer system  140 . 
       FIG. 2  is a block diagram illustrating a constitution of the smart card illustrated in  FIG. 1 . 
     Referring to  FIG. 2 , the smart card  100  includes contact pads  201 ˜ 207 , an interface circuit  210  and an internal circuit block  220 . The contact pads  201 ˜ 207  may be connected to a host such as the payment terminal  110 , the electronic toll collection system  120  and the computer system  140  illustrated in  FIG. 1  in a contact type mode or in a contactless type mode through an antenna. Although only seven contact pads  201 ˜ 207  are illustrated in  FIG. 2 , the inventive concept follows the number and locations of contact pads provided in the international organization for standardization (ISO) 7816, which is a smart card standard. 
     The contact pad  201  is used to receive a power needed for the smart card  100  from the external host. The contact pads  202  and  203  are used to transmit data between the smart card  100  and the host. When the smart card  100  communicates with the host in the USB mode, the contact pads  202  and  203  are used to transmit data signals D+ and D−. In the case that the smart card  100  communicates with the host in a contactless mode, the contact pads  202  and  203  are connected to an antenna to transmit wireless signals L 1  and L 2 . The contact pad  204  is used to receive a clock from the host. The clock is used to drive the internal circuit block  220 . The contact pad  205  is used to receive a reset signal to reset the interface module  210  and the internal circuit block  220 . The contact pad  206  is used to transmit a data signal in a serial input output (SIO) mode, which is one of the contact modes. The contact mode  207  is used to provide an electrical ground between the host and the smart card  100 . 
     The interface module  210  includes a mode selector  211 , a USB interface  212 , a contactless interface  213  and a serial input output (SIO) interface  214 . The mode selector  211  determines whether the power supply voltage (VDD) is provided through the contact pad  201  and enables any one of the USB mode interface  212  and the contactless interface  213  according to whether the power supply voltage (VDD) is provided. That is, when the power supply voltage (VDD) is provided through the contact pad  201 , the mode selector  211  enables the USB interface  212 . When the power supply voltage (VDD) is not provided through the contact pad  201 , the mode selector  211  enables the contactless interface  213 . The mode selector  211  also provides selected mode information to the internal circuit block  220 . 
     If the contactless interface  213  is enabled by the mode selector  211 , the contactless interface  213  performs an interface connection so that the internal circuit block  220  communicates with the host through the contact pads  202  and  203  by the method defined in the international organization for standardization (ISO) 14443. For instance, the contactless interface  213  converts the wireless signals L 1  and L 2  received through the contact pads  202  and  203  into a clock signal and a data signal suitable for the internal circuit block  220 . After coding a transmission signal outputted from the internal circuit block  220  using a Manchester code method and modulating the coded transmission signal using an on-off key (OOK) method, the contactless interface  213  transmits the modulated transmission signal to the host through the contact pads  202  and  203 . Since the contactless interface  213  generates a power supply from the wireless signals L 1  and L 2  received through the contact pads  202  and  203 , the contactless interface  213  is not required to be supplied with a separate power supply. 
     If the USB interface  212  is enabled by the mode selector  211 , the USB interface  212  transmits the data signals D+ and D− to the host through the contact pad  202  and  203  in one of a high speed mode, a low speed mode, a full speed mode and a super speed mode defined in the USB standard. The USB interface  212  sets a USB operation mode according to the data signals D+ and D− received from the host through the contact pads  202  and  203  and performs an interface operation suitable for the USB operation mode. The USB interface  212  determines whether a signal received through the contact pads  202  and  203  is suited to the USB standard and provides the determined result to the mode selector  211 . If a signal received through the contact pads  202  and  203  is determined not to be suited to the USB standard while the power supply voltage VDD is supplied through the contact pad  201 , the mode selector  211  disables the USB interface  212  and operates in a serial input output (SIO) mode. 
     That is, if the power supply voltage VDD is supplied to the mode selector  211  through the contact pad  201 , the mode selector  211  sets an operation mode in the USB mode to enable the USB interface  212 . However, if the power supply voltage VDD is supplied through the contact pad  201  but a signal suitable for the USB standard is not received through the contact pads  202  and  203 , the mode selector  211  disables the USB interface  212  and the contactless interface  213 . At this time, the interface module  210  operates in a serial input output (SIO) mode by the SIO interface  214 . 
     The SIO interface  214  starts an operation in response to a clock, a reset signal and a data signal received from the contact pads  204 ˜ 206  and performs a communication interface between the host and the internal circuit block  220 . 
     The internal circuit block  220  includes a microprocessor, a read only memory (ROM), a random access memory (RAM), an electrically erasable and programmable read only memory (EEPROM) and a security controller. The internal circuit block  220  communicates with the host through the interface module  210  and the contact pads  201 ˜ 207  and performs a predetermined operation. 
     The smart card  100  illustrated in  FIG. 2  can communicate with the host not only through the SIO mode and a contactless mode, but also through the USB mode using the contact pads  201 ˜ 207 . 
       FIG. 3  is a flow chart illustrating an operation sequence of a smart card in accordance with exemplary embodiments of the inventive concept. 
     Referring to  FIGS. 2 and 3 , if a power supply is supplied to the smart card  100 , the smart card  100  is reset (operation  300 ). In a reset state, if the power supply voltage VDD is not supplied from an external source through the contact pad  201  (operation  310 ), the interface module  210  in the smart card  100  operates in a contactless mode (operation  320 ). In a contactless mode, the signals L 1  and L 2  received through an antenna (not shown) and the contact pads  202  and  203  are provided to the internal circuit block  220  through the contactless interface  213  and a signal outputted from the internal circuit block  220  is transmitted to the host through the contactless interface  213 , the contact pads  202  and  203  and the antenna. 
     If the power supply voltage VDD is supplied from an external source through the contact pad  201  and the data signals D+ and D− are received through the contact pads  202  and  203  (operation  330 ), the interface module  210  operates in the USB mode (operation  340 ). In the USB mode, the data signals D+ and D− received through the contact pads  202  and  203  are provided to the internal circuit block  220  through the USB interface  212  and a signal outputted from the internal circuit block  220  is transmitted to the host through the USB interface  212 . 
     If the power supply voltage VDD is supplied from an external source through the contact pad  201  but any signal is not received through the contact pads  202  and  203  (operation  350 ), the interface module  210  operates in the SIO mode (operation  360 ). In the SIO mode, the interface module  210  operates in response to a signal received through the contact pads  204 ,  205  and  206 . 
     If the power supply voltage VDD is supplied from an external source through the contact pad  201  and a signal, which is not suited to the USB standard, is received through the contact pads  202  and  203  (operation  350 ), the interface module  210  operates in the SIO mode and a contactless mode. That is, the contactless interface  213  communicates with the host through the contact pads  202  and  203  in a contactless type mode and the SIO interface  214  communicates with the host through the contact pads  204 ,  205  and  206  in a contact type mode. The SIO mode and a contactless mode may occur when a user pays a subway fee in a contactless mode in the state such that the smart card  100  is in contact with the host such as a card reader. 
     While the smart card described above is adapted to the number standard of contact pads defined in a smart card standard, it can operate in the USB mode, a contactless mode and a contact mode. 
       FIG. 4  is a drawing illustrating a smart card module in accordance with exemplary embodiments of the present inventive concept. 
     Referring to  FIG. 4 , a smart card module  400  built in a smart card includes a printed circuit board (PCB) on which an integrated circuit chip  410  is mounted. An integrated circuit chip  410  is mounted on one side of the printed circuit board (PCB) and the other side of the printed circuit board (PCB) includes external contact pads provided in the international organization for standardization (ISO) 7916. The smart card module  400  comprises eight external contact pads provided in the international organization for standardization (ISO) 7916. When fabricating a smart card, a method is used that first, the smart card module  400  is constituted by packing the integrated circuit chip  410  on a printed circuit board (PCB) according to a chip on board (COB) package technology and then the smart card module  400  is inserted into a cavity of the card body. 
     The integrated circuit chip  410  includes chip pads  411 ˜ 417  connected to an interface circuit integrated therein. The chip pads  411 ˜ 417  are connected to contact pads  401 ˜ 407  of the smart card module  400 , respectively. The chip pads  411 ˜ 417  of the integrated circuit chip  410  may be connected to the contact pads  401 ˜ 407  in a wire bonding method. That is, the chip pad  411  may be connected to the contact pad  401  by a bonding wire  421  and the chip pad  412  may be connected to the contact pad  402  by the bonding wire  421 . The contact pads  401 ˜ 407  may be connected to external contact pads arranged on an opposite side of the smart card module  400  through contact plugs. In particular, the contact pads  401  and  402  may be connected to an antenna pattern (not shown) mounted on the printed circuit board (PCB) of the smart card module  400 . Also, the contact pads  401  and  402  are connected to external contact pads of the smart card module  400  to be connected to USB data terminals of a host. 
     In the example illustrated in  FIG. 4 , when the integrated circuit chip  410  operates in the USB mode, it transmits/receives the data signals D+ and D− to/from the host through the chip pads  411  and  412 , and when the integrated circuit chip  410  operates in a contactless mode, it transmits/receives the wireless signals L 1  and L 2  to/from the host through the chip pads  411  and  412 . 
       FIG. 5  is a drawing illustrating a smart card module in accordance with other exemplary embodiments of the inventive concept. 
     Referring to  FIG. 5 , unlike  FIG. 4 , an integrated circuit chip  510  mounted on a smart card module  500  includes chip pads  511  and  512  for the USB mode and chip pads  519  and  513  for a contactless mode that are separated from each other. That is, when the integrated circuit chip  510  operates in the USB mode, it transmits/receives the data signals D+ and D− to/from a host through the chip pads  511  and  512 , and when the integrated circuit chip  510  operates in a contactless mode, it transmits/receives the wireless signals L 1  and L 2  to/from the host through the chip pads  519  and  513 . Contact pads  501  and  502  are connected to an antenna pattern (not shown) mounted on a printed circuit board (PCB) of the smart card module  500 . Also, the contact pads  501  and  502  are connected to external contact pads of the smart card module  500  to be connected to USB data terminals of the host. 
     However, unlike the smart card module  400  illustrated in  FIG. 4 , the chip pads  511  and  519  are connected to the contact pad  501  in common by bonding wires  521  and  522  and the chip pads  512  and  513  are connected to the contact pad  502  in common by bonding wires  523  and  524 . 
     In the integrated circuit chip  510  mounted on a smart card module  500 , the chip pads  511  and  512  for the USB mode and the chip pads  519  and  513  for a contactless mode are separately formed. An interface module (not shown) in the integrated circuit chip  510  is supplied with the power supply voltage VDD from a chip pad  516 , and when receiving signals D+ and D− suitable for the USB standard from the chip pads  511  and  512 , the interface module operates in the USB mode. If the interface module is not supplied with the power supply voltage VDD from the chip pad  516 , it operates in a contactless mode using the chip pads  519  and  513 . 
     According to embodiments of the inventive concept, a smart card can be realized that can support various interfaces through eight electric contacts defined in a regulation. 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true spirit and scope of the inventive concept. Thus, to the maximum extent allowed by law, the scope of the inventive concept is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.