Smart card connection circuit of electronic device and electronic device
View Patent ↗A smart card connection circuit of an electronic device which includes a card holder, a travel switch, and a switching unit; a contact of the travel switch is located in the card holder, and an output end of the travel switch is connected to a control end of the switching unit; and when a smart card at a preset position in the card holder leaves the preset position, the smart card leaves the contact of the travel switch, the travel switch controls the switching unit to switch to a second output end, and each signal cable pin on the card holder is grounded by using the switching unit before a power cable pin on the card holder is grounded by using the switching unit. The present invention is applied to electronic devices such as a mobile phone and a tablet computer.
1. A smart card connection circuit of an electronic device, comprising;
a card holder;
a travel switch; and
a switching unit,
wherein a power cable pin and each signal cable pin on the card holder are connected to corresponding interfaces at an input end of the switching unit,
wherein a contact of the travel switch is located in the card holder, and an output end of the travel switch is connected to a control end of the switching unit, and
wherein the smart card leaves the contact of the travel switch, the travel switch controls the switching unit to switch to a second output end, and each signal cable pin on the card holder is grounded by using the switching unit before the power cable pin on the card holder is grounded by using the switching unit when a smart card at a preset position in the card holder leaves the preset position.
2. The smart card connection circuit according to claim 1 , wherein, when there is a smart card at the preset position in the card holder, the smart card touches the contact of the travel switch, the travel switch controls the switching unit to switch to a first output end, and the power cable pin and each signal cable pin on the card holder are connected to a modem of the electronic device by using the switching unit.
3. The smart card connection circuit according to claim 1 , wherein, at the second output end, a first resistor is connected in series between each signal cable pin on the card holder and a ground cable, wherein a second resistor is connected in series between the power cable pin on the card holder and the ground cable, and wherein a resistance value of the first resistor is less than that of the second resistor.
4. The smart card connection circuit according to claim 3 , wherein the output end of the travel switch is further connected to a general purpose input/output (GPIO) interface of the modem.
5. The smart card connection circuit according to claim 4 , wherein the output end of the travel switch is further connected to a GPIO interface of an application processor of the electronic device.
6. The smart card connection circuit according to claim 5 , wherein the output end of the travel switch is connected, by using a phase inverter, to the GPIO interface of the modem and to the GPIO interface of the application processor.
7. The smart card connection circuit according to claim 6 , wherein, in the travel switch, the output end is connected to a high-level voltage by using a pull-up resistor, wherein the output end is further grounded by using the contact, and wherein the travel switch outputs a high-level voltage when the contact is open and the travel switch outputs a low-level voltage when the contact is closed.
8. The smart card connection circuit according to claim 7 , wherein the output end of the travel switch is connected to a filtering unit.
9. The smart card connection circuit according to claim 1 , wherein the switching unit is a logic circuit, and wherein each pin on the card holder is connected to each corresponding pin at the input end of the switching unit.
10. The smart card connection circuit according to claim 1 , wherein the smart card is a subscriber identity module (SIM) card.