Smart card and smart card power switching circuit

Abstract

The present invention belongs to the technical field of smart cards, and provides a smart card and a power switching circuit of the smart card. The power switching circuit of the smart card is connected to the load of the smart card, and includes: 7816 contacts, configured to be electrically connected to a contact card reader for communication; an NFC antenna, configured to wirelessly communicate with an NFC card reader; a first voltage conversion unit, connected to the 7816 contacts, configured to convert the contact voltage output by the 7816 contacts into a first voltage; a second voltage conversion unit, connected to the NFC antenna, configured to convert the antenna voltage output by the NFC antenna into a second voltage; and a switching unit, respectively connected to the first voltage conversion unit and the second voltage conversion unit, configured to select the first voltage or the second voltage to power the load.

Description

Technical Field

[0001] The invention belongs to the technical field of smart cards, and in particular relates to a smart card and a power switching circuit of the smart card. Background Art

[0002] Near Field Communication (NFC) is a short-range high-frequency radio technology that operates at a frequency of 13.56MHz. Its transmission speed is 106Kbit / s, 212Kbit / s or 424Kbit / s. Currently, near field communication has passed the ISO / IEC 18092 international standard, ECMA-340 standard and ETSI TS 102 190 standard. 7816 is the smart card standard ISO / IEC 7816 announced by the International Organization for Standardization. It specifies the relevant specifications of contact smart cards, including physical characteristics, interface specifications, transmission protocols and command exchange formats. The 7816 contacts are the physical interface of the standard and also the contact physical interface for smart cards to connect to the outside.

[0003] For smart cards that have both 7816 contacts and NFC as energy sources, the traditional solution is generally to connect the 7816 contacts and NFC power lines to the power supply circuit through diodes. When the power load on the smart card is large, the current flowing through the diode is large, and the voltage drop on the diode is large, which cannot meet the power supply needs of some loads with higher power supply voltage requirements, resulting in unstable operation of the smart card system. Summary of the invention

[0004] The purpose of the present invention is to provide a smart card and a power switching circuit for the smart card, aiming to solve the problem that the traditional technical solution cannot meet the power supply demand of some loads with higher power supply voltage requirements, resulting in unstable operation of the smart card system.

[0005] A power switching circuit of a smart card is connected to a load of the smart card, and the power switching circuit of the smart card comprises:

[0006] 7816 contacts configured to be electrically connected to a contact card reader for communication;

[0007] an NFC antenna configured to wirelessly communicate with an NFC card reader;

[0008] A first voltage conversion unit, connected to the contact 7816, and configured to convert the contact voltage output by the contact 7816 into a first voltage;

[0009] A second voltage conversion unit, connected to the NFC antenna, configured to convert an antenna voltage output by the NFC antenna into a second voltage;

[0010] The switching unit is connected to the first voltage conversion unit and the second voltage conversion unit respectively, and is configured to select the first voltage or the second voltage to supply power to the load.

[0011] In one embodiment, the comparison unit is connected between the 7816 contact and the NFC antenna, and is configured to compare the contact voltage with the antenna voltage, and output power to the switching unit according to the comparison result.

[0012] In one embodiment, the comparison unit includes a first diode, an anode of the first diode is connected to the 7816 contact, a cathode of the first diode is connected to the NFC antenna, and the NFC antenna is connected to a power supply terminal of the switching unit.

[0013] In one embodiment, the first voltage conversion unit includes a first voltage conversion chip, an input end of the first voltage conversion chip is connected to the 7816 contacts, and an output end of the first voltage conversion chip is connected to the switching unit.

[0014] In one embodiment, the second voltage conversion unit includes a second voltage conversion chip, an input end of the second voltage conversion chip is connected to the NFC antenna, and an output end of the second voltage conversion chip is connected to the switching unit.

[0015] In one embodiment, the switching unit includes a switching chip, a first input end of the switching chip is connected to the first voltage conversion unit, a second input end of the switching chip is connected to the second voltage conversion unit, a control end of the switching chip is connected to the output end of the first voltage conversion unit, and an output end of the switching chip is connected to the load.

[0016] In one embodiment, the power switching circuit of the smart card further includes a second diode, wherein the anode of the second diode is connected to the output end of the first voltage conversion unit, the cathode of the second diode is connected to the NFC antenna, and the cathode of the second diode is also connected to the power end of the switching unit.

[0017] In addition, a smart card is provided, which includes: a load and the power switching circuit of the smart card connected to the load.

[0018] The power switching circuit of the smart card converts the contact voltage output by the 7816 contact into a first voltage through the first voltage conversion unit, converts the antenna voltage output by the NFC antenna into a second voltage through the second voltage conversion unit, and selects the first voltage or the second voltage to power the load through the switching unit. The load power supply is switched by the switching unit with lower power consumption to ensure the power supply demand of the load, thereby ensuring the stability of the smart card system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a power switching circuit of a smart card provided by an embodiment of the present invention;

[0020] Figure 2 for Figure 1 An exemplary circuit schematic diagram of a first voltage conversion unit in a power switching circuit of a smart card is shown;

[0021] Figure 3 for Figure 1 An exemplary circuit schematic diagram of a second voltage conversion unit in a power switching circuit of a smart card is shown;

[0022] Figure 4 for Figure 1 An example circuit schematic diagram of a switching unit in a power switching circuit of a smart card is shown. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Figure 1 The schematic diagram of the structure of the power switching circuit of the smart card provided by the preferred embodiment of the present invention is shown. For the convenience of explanation, only the part related to the present embodiment is shown, which is described in detail as follows:

[0025] like Figure 1 As shown, the power switching circuit 1 of the smart card is connected to the load 2 of the smart card, and the power switching circuit 1 of the smart card includes a 7816 contact 10, an NFC antenna 20, a first voltage conversion unit 30, a second voltage conversion unit 40 and a switching unit 50. The switching unit 50 determines the access power supply, and selects the corresponding power supply to connect to the back-end load 2, thereby realizing the selection of the corresponding power supply according to the type of power supply accessed in the smart card usage scenario, and switching the load power supply through the switching unit with lower power consumption, thereby reducing circuit loss, ensuring the power supply demand of the load, and thus ensuring the stability of the smart card system.

[0026] The 7816 contact 10 is configured to be electrically connected to the contact card reader for communication, and provides the required power to the smart card while realizing the communication between the smart card and the contact card reader. The communication between the 7816 contact 10 and the contact card reader meets the 7816 protocol. The NFC antenna 20 is configured to wirelessly communicate with the NFC card reader. The smart card communicates with the NFC card reader through the NFC antenna 20 and obtains data and power through the induction coil.

[0027] like Figure 2 As shown, the first voltage conversion unit 30 is connected to the 7816 contact 10, and is used to convert the contact voltage 7816_VCC output by the 7816 contact 10 into the first voltage CARD_VCC; the first voltage conversion unit 30 includes a first voltage conversion chip U1, the input end of the first voltage conversion chip U1 is connected to the 7816 contact 10, and the output end of the first voltage conversion chip U1 is connected to the switching unit 50. Further, the first voltage conversion unit 30 also includes a first capacitor C1 and a second capacitor C2, the first capacitor C1 is connected between the input end of the first voltage conversion chip U1 and the ground, and the second capacitor C2 is connected between the output end of the first voltage conversion chip U1 and the ground.

[0028] like Figure 3 As shown, the second voltage conversion unit 40 is connected to the NFC antenna 20, and is used to convert the antenna voltage ANT_VCC output by the NFC antenna 20 into the second voltage NFC_VCC; the second voltage conversion unit 40 includes a second voltage conversion chip U2, the input end of the second voltage conversion chip U2 is connected to the NFC antenna 20, and the output end of the second voltage conversion chip U2 is connected to the switching unit 50. Further, the second voltage conversion unit 40 also includes a third capacitor C3 and a fourth capacitor C4, the third capacitor C3 is connected between the input end of the second voltage conversion chip U2 and the ground, and the fourth capacitor C4 is connected between the output end of the second voltage conversion chip U2 and the ground.

[0029] like Figure 4 As shown, the switching unit 50 is connected to the first voltage conversion unit 30 and the second voltage conversion unit 40 respectively, and is configured to select the first voltage CARD_VCC or the second voltage NFC_VCC to power the load 2. The switching unit 50 includes a switching chip U3, a first input end of the switching chip U3 is connected to the first voltage conversion unit 30, a second input end of the switching chip U3 is connected to the second voltage conversion unit 40, a control end of the switching chip U3 is connected to the output end of the first voltage conversion unit 30, and an output end of the switching chip U3 is connected to the load 2. The first voltage conversion unit 30 and the second voltage conversion unit 40 are connected to the switching unit 50 for selection, and the first voltage CARD_VCC converted from the contact voltage 7816_VCC output by the 7816 contact 10 is the control logic of the switching chip U3. When the 7816 contact 10 is powered, the switching unit 50 connects the first voltage CARD_VCC to the load 2, and when the 7816 contact 10 is not powered, the switching unit 50 connects the second voltage NFC_VCC to the load 2.

[0030] Furthermore, a comparison unit 60 is included, and the comparison unit 60 is between the 7816 contact 10 and the NFC antenna 20, and is used to compare the contact voltage 7816_VCC and the antenna voltage ANT_VCC, and output power to the switching unit 50 according to the comparison result of the comparison unit 60. The comparison unit 60 includes a first diode D1, and the anode of the first diode D1 is connected to the 7816 contact 10, and the cathode of the first diode D1 is connected to the NFC antenna 20, and the NFC antenna 20 is connected to the power supply terminal of the switching unit 50.

[0031] When the smart card is inserted into the contact card reader, the contact 10 of 7816 is powered, the contact voltage 7816_VCC has voltage, the antenna voltage ANT_VCC has no voltage, the first diode D1 is turned on, and the switching unit 50 is powered by the contact voltage 7816_VCC through the first diode D1. At this time, the logic selection pin of the switching chip U3 is high, and the first voltage CARD_VCC output by the first voltage conversion unit 30 is connected to the load 2 to power the load 2.

[0032] When the card is close to the NFC reader, there is no voltage at the contact 10 of 7816, the NFC antenna 20 senses and outputs the antenna voltage ANT_VCC, the contact voltage 7816_VCC is 0, the first diode D1 is turned off, and the antenna voltage ANT_VCC is converted into the second voltage NFC_VCC through the second voltage conversion unit 40. At the same time, the antenna voltage ANT_VCC powers the switching unit 50, the first voltage CARD_VCC is 0, the logic selection pin of the switching chip U3 is low, and the second voltage NFC_VCC is connected to the load 2 to power the load 2. At this time, the first voltage conversion unit 30 does not work.

[0033] In one embodiment, the power switching circuit 1 of the smart card further includes a second diode D2, the anode of the second diode D2 is connected to the output end of the first voltage conversion unit 30, the cathode of the second diode D2 is connected to the NFC antenna 20, and the cathode of the second diode D2 is also connected to the power end of the switching unit 50. When the smart card is inserted into the contact card reader, the 7816 contact 10 is powered, the contact voltage 7816_VCC has a voltage, the antenna voltage ANT_VCC has no voltage, and the power end of the switching unit 50 is powered by the first voltage CARD_VCC through the second diode D2. At this time, the logic selection pin of the switching chip U3 is high, and the first voltage CARD_VCC output by the first voltage conversion unit 30 is connected to the load 2 to power the load 2.

[0034] When the card is close to the NFC reader, there is no voltage at the contact 10 of 7816, the NFC antenna 20 senses and outputs the antenna voltage ANT_VCC, the contact voltage 7816_VCC is 0, the second diode D2 is turned off, and the antenna voltage ANT_VCC is converted into the second voltage NFC_VCC through the second voltage conversion unit 40. At the same time, the antenna voltage ANT_VCC powers the switching unit 50, the first voltage CARD_VCC is 0, the logic selection pin of the switching chip U3 is low, and the second voltage NFC_VCC is connected to the load 2 to power the load 2. At this time, the first voltage conversion unit 30 does not work.

[0035] In one embodiment, the first diode D1 and the second diode D2 exist at the same time. When the smart card is inserted into the contact card reader, the 7816 contact 10 is powered, the contact voltage 7816_VCC has voltage, the antenna voltage ANT_VCC has no voltage, the first diode D1 is turned on, the second diode D2 is turned off, and the switching unit 50 is powered by the contact voltage 7816_VCC through the first diode D1. At this time, the logic selection pin of the switching chip U3 is high, and the first voltage CARD_VCC output by the first voltage conversion unit 30 is connected to the load 2 to power the load 2.

[0036] When the card is close to the NFC reader, there is no voltage at the contact 10 of 7816, the NFC antenna 20 senses and outputs the antenna voltage ANT_VCC, the contact voltage 7816_VCC is 0, the first diode D1 is turned off, the second diode D2 is turned off, and the antenna voltage ANT_VCC is converted into the second voltage NFC_VCC through the second voltage conversion unit 40. At the same time, the antenna voltage ANT_VCC powers the switching unit 50, the first voltage CARD_VCC is 0, the logic selection pin of the switching chip U3 is low, and the second voltage NFC_VCC is connected to the load 2 to power the load 2. At this time, the first voltage conversion unit 30 does not work.

[0037] On the basis of the power switching circuit 1 of the smart card described above, an embodiment of the present invention further provides a smart card, which includes: a load and the power switching circuit of the smart card described above connected to the load.

[0038] In summary, the embodiment of the present invention provides a smart card and a power switching circuit 1 for the smart card, wherein the power switching circuit 1 for the smart card includes a 7816 contact 10, an NFC antenna 20, a first voltage conversion unit 30, a second voltage conversion unit 40 and a switching unit 50. The switching unit 50 determines the access power supply, and selects the corresponding power supply to connect to the back-end load 2, thereby realizing the selection of the corresponding power supply according to the type of power supply accessed in the smart card usage scenario, and switching the load power supply through the switching unit with lower power consumption, thereby reducing circuit loss, ensuring the power supply demand of the load, and thus ensuring the stability of the smart card system.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A power switching circuit of a smart card, connected to a load of the smart card, characterized in that: The power switching circuit of the smart card comprises: 7816 contacts configured to be electrically connected to a contact card reader for communication; an NFC antenna configured to wirelessly communicate with an NFC card reader; A first voltage conversion unit, connected to the contact 7816, and configured to convert the contact voltage output by the contact 7816 into a first voltage; A second voltage conversion unit, connected to the NFC antenna, configured to convert an antenna voltage output by the NFC antenna into a second voltage; a switching unit, connected to the first voltage conversion unit and the second voltage conversion unit respectively, and configured to select the first voltage or the second voltage to supply power to the load; A comparison unit, the comparison unit is connected between the 7816 contact and the NFC antenna, and is configured to compare the contact voltage with the antenna voltage, and output power to the switching unit according to the comparison result; a second diode, wherein an anode of the second diode is connected to an output end of the first voltage conversion unit, a cathode of the second diode is connected to the NFC antenna, and a cathode of the second diode is also connected to a power supply end of the switching unit; The comparison unit includes a first diode, an anode of the first diode is connected to the 7816 contact, a cathode of the first diode is connected to the NFC antenna, and the NFC antenna is connected to a power supply terminal of the switching unit.

2. The power switching circuit of the smart card as claimed in claim 1, characterized in that: The first voltage conversion unit includes a first voltage conversion chip, an input end of the first voltage conversion chip is connected to the 7816 contacts, and an output end of the first voltage conversion chip is connected to the switching unit.

3. The power switching circuit of the smart card as claimed in claim 1, characterized in that: The second voltage conversion unit includes a second voltage conversion chip, an input end of the second voltage conversion chip is connected to the NFC antenna, and an output end of the second voltage conversion chip is connected to the switching unit.

4. The power switching circuit of the smart card as claimed in claim 1, characterized in that: The switching unit includes a switching chip, a first input end of the switching chip is connected to the output end of the first voltage conversion unit, a second input end of the switching chip is connected to the output end of the second voltage conversion unit, a control end of the switching chip is connected to the output end of the first voltage conversion unit, and an output end of the switching chip is connected to the load.

5. A smart card, characterized in that: The smart card comprises: a load and a power switching circuit for the smart card according to any one of claims 1 to 4 connected to the load.

Images