Magnetic secure transmission (MST) device, MST system and controller including the same
A magnetic secure transmission system includes an inductor, a switching circuit connected to the inductor, and a control circuit. The control circuit controls the switching circuit to adjust a level of a current in the inductor by a first amount over a data transmission period, such that the inductor emits a magnetic pulse including a first magnitude during the data transmission period. The control circuit controls the switching circuit to adjust the level of the current in the inductor such that the level of the current is increased and decreased repeatedly by a second amount between two different levels during a data non-transmission period, and the inductor emits a magnetic pulse including a second magnitude during the data non-transmission period. The second amount is less than the first amount, the first magnitude is greater than a threshold value and the second magnitude is less than the threshold value.
1. A magnetic secure transmission (MST) system, comprising:
an inductor;
a switching circuit connected to the inductor; and
a control circuit,
the control circuit being configured to control the switching circuit to adjust a level of a current in the inductor by a first amount over a data transmission period, such that the inductor emits a magnetic pulse including a first magnitude during the data transmission period,
the control circuit being configured to control the switching circuit to adjust the level of the current in the inductor such that the level of the current in the inductor repeatedly is increased linearly by a second amount and decreased linearly by the second amount between two different levels during a data non-transmission period, and the inductor emits a magnetic pulse including a second magnitude during the data non-transmission period,
the second amount being less than the first amount,
the first magnitude being greater than a threshold value corresponding to a noise level, and
the second magnitude being less than the threshold value.
2. The MST system of claim 1 , wherein
the control circuit is configured to control the switching circuit to decrease the current in the inductor from a first level to a second level by a first constant slope during a first sub-period of a plurality of sub-periods of the data non-transmission period,
the control circuit is configured to control the switching circuit to increase the current in the inductor from the second level to the first level by a second constant slope during a second sub-period of the plurality of sub-periods of the data non-transmission period, the second sub-period being successive to the first sub-period,
the control circuit configured to set the first level and the second level, and
the first sub-period and the second sub-period are alternatingly repeated.
3. The MST system of claim 2 , wherein a magnitude of the first constant slope is the same as a magnitude of the second constant slope.
4. The MST system of claim 3 , wherein the control circuit is configured to control the switching circuit such that a duration of the first sub-period is the same as a duration of the second sub-period.
5. The MST system of claim 2 , wherein a magnitude of the second constant slope is smaller than a magnitude of the first constant slope.
6. The MST system of claim 5 , wherein the control circuit is configured to control the switching circuit such that a duration of the second sub-period is greater than a duration of the first sub-period.
7. The MST system of claim 2 , wherein
the data non-transmission period is successive to the data transmission period corresponding to a first type,
the control circuit is configured to control the switching circuit to increase linearly the current in the inductor from a third level to the first level during the first type of data transmission period, and
the third level is smaller than the second level.
8. The MST system of claim 1 , wherein
the data non-transmission period is successive to the data transmission period corresponding to a second type,
the control circuit is configured to control the switching circuit to decrease linearly the current in the inductor from a first level to a fourth level during the second type of data transmission period,
the first level is greater than a zero, and
the fourth level is smaller than the zero.
9. The MST system of claim 8 , wherein
the control circuit is configured to control the switching circuit to increase the current in the inductor from the fourth level to a fifth level by a first constant slope during a first sub-period of a plurality of sub-periods of the data non-transmission period,
the control circuit is configured to control the switching circuit to decrease the current in the inductor from the fifth level to the fourth level by a second constant slope during a second sub-period of the plurality of sub-periods of the data non-transmission period, the second sub-period being successive to the first sub-period,
the control circuit configured to set the first level, the fourth level and the fifth level, and
the first sub-period and the second sub-period are alternatingly repeated.
10. The MST system of claim 9 , wherein a magnitude of the first constant slope is the same as a magnitude of the second constant slope.
11. The MST system of claim 9 , wherein a magnitude of the second constant slope is smaller than a magnitude of the first constant slope.
12. The MST system of claim 1 , wherein
the switching circuit includes,
a first switching element connected between a power node and a first node,
a second switching element connected between the first node and a ground node,
a third switching element connected between the power node and a second node, and
a fourth switching element connected between second node and the ground node,
the first node is connected to a first end of the inductor, and
the second node is connected to a second end of the inductor.
13. The MST system of claim 12 , wherein
the first switching element and the second switching element are serially connected to each other between the power node and the ground node, and
the third switching element and the fourth switching element are serially connected to each other between the power node and the ground node.
14. The MST system of claim 12 , wherein
the first switching element and the third switching element are NMOS transistors, and
the second switching element and the fourth switching element are PMOS transistors.
15. The MST system of claim 14 , wherein
the first switching element and the third switching element are NMOS transistors, and
the second switching element and the fourth switching element are NMOS transistors.
16. The MST system of claim 1 , further comprising:
a MST device, wherein
the MST device includes the switching circuit, and
the MST device further includes the control circuit, the inductor, or both the control circuit and the inductor.
17. A payment system, comprising:
the MST system of claim 1 ;
a MST device in the MST system, the MST device including the switching circuit; and
a mobile device coupled to the MST device, wherein
the mobile device includes a wallet application configured to send magnetic strip data to the control circuit,
the control circuit is configured to control the switching circuit to adjust the level of the current in the inductor, based on the magnetic strip data, to emit a plurality of magnetic pulses including the first magnitude during a plurality of data transmission periods, respectively.
18. A magnetic secure transmission (MST) device, comprising:
a switching circuit including a first port and a second port that are configured to connect to a first end and a second end, respectively, of an inductor external to the MST; and
a control circuit coupled to the switching circuit,
the control circuit being configured to control the switching circuit to adjust a level of a current in the inductor by a first amount over a data transmission period, such that the inductor emits a magnetic pulse including a first magnitude during the data transmission period,
the control circuit being configured to control the switching circuit to adjust the level of the current in the inductor such that the level of the current in the inductor repeatedly is increased linearly by a second amount and decreased linearly by the second amount between two different levels during a data non-transmission period, and the inductor emits a magnetic pulse including a second magnitude during the data non-transmission period,
the second amount being less than the first amount,
the first magnitude being greater than a threshold value corresponding to a noise level, and
the second magnitude being less than the threshold value.
19. The MST device of claim 18 , wherein
the switching circuit includes,
a first switching element connected between a power node and a first node,
a second switching element connected between the first node and a ground node,
a third switching element connected between the power node and a second node, and
a fourth switching element connected between second node and the ground node,
the first node is connected to the first port, and
the second node is connected to the second port.
20. A controller, comprising:
a memory; and
an application processor coupled to the memory,
the application processor being configured to provide switching control signals to a switching circuit coupled to an inductor for adjusting a level of a current in the inductor,
the application processor being configured to control the switching circuit to adjust the level of the current in the inductor by a first amount over a data transmission period, such that the inductor emits a magnetic pulse including a first magnitude during the data transmission period,
the application processor being configured to control the switching circuit to adjust the level of the current in the inductor such that the level of the current in the inductor repeatedly is increased linearly by a second amount and decreased linearly by the second amount between two different levels during a data non-transmission period, and the inductor emits a magnetic pulse including a second magnitude during the data non-transmission period,
the second amount being less than the first amount,
the first magnitude being greater than a threshold value corresponding to a noise level, and
the second magnitude being less than the threshold value.