Power switch circuit structure of identification card machine

Abstract

The utility model relates to a card identification machine power switch circuit structure which comprises a power switch, a rapid shutdown circuit used for being connected with a power supply and a startup spark-proof soft start circuit used for being connected with a load equivalent circuit. A COM pin of the power switch is grounded through a resistor Rb, a pin 3 of the power switch is connected with the startup spark-proof soft start circuit, a pin 1 of the power switch is connected with the rapid shutdown circuit, and the rapid shutdown circuit is connected with the startup spark-proof soft start circuit; when the power switch is turned on, the COM pin of the power switch is connected with the pin 3 of the power switch; when the power switch is turned off, the COM pin of the power switch is connected with the pin 1 of the power switch; the problems of spark at the starting moment and overlong shutdown time can be solved at the same time, and the use experience of a user is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of a power switch circuit structure of a card machine, in particular to a power switch circuit structure of a card machine. Background Art

[0002] like Figure 1 As shown, in traditional power-on circuits, when the power adapter is plugged in and the switch is turned on, the capacitor is momentarily short-circuited, resulting in excessive current flow and sparks on the switch spring or connector interface, shortening the life of the switch and connector and damaging system components. However, when the switch is turned off, the adapter power is completely disconnected, and the remaining power in the system dissipates quickly, allowing the switch to be turned on again immediately to resume operation.

[0003] like Figure 2 As shown, in order to solve the spark phenomenon when the switch is turned on, a MOS tube U1 circuit is generally used. The capacitance characteristics are used to slowly change the gate voltage of the MOS tube U1, allowing the MOS tube U1 to slowly turn on, thereby reducing or eliminating the plug-in spark.

[0004] However, when using this method to shut down the system, the MOS tube U1 turns off slowly, and the power adapter continues to supply power to the system before it is completely shut down, causing the system to be completely powered off for a long time.

[0005] The next time you turn on the switch, the time must be extended. Otherwise, the system will not be able to reset correctly and fail to restart due to the long shutdown time. This is why many electronic products require users to wait more than 10 seconds after shutting down before restarting.

[0006] Therefore, in the present utility model patent application, the applicant has carefully studied a power switch circuit structure of a card reader to solve the above problems. Utility Model Content

[0007] The present invention aims to address the deficiencies in the above-mentioned prior art and aims to provide a power switch circuit structure for a card reader, which can simultaneously solve the problems of sparks at startup and long shutdown time, thereby greatly improving the user experience.

[0008] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0009] A power switch circuit structure for a card reader includes a power switch, a fast shutdown circuit for connecting to a power supply, and a power-on anti-spark soft start circuit for connecting to a load equivalent circuit;

[0010] The COM pin of the power switch is grounded through a resistor Rb, pin 3 of the power switch is connected to a power-on spark-proof soft-start circuit, and pin 1 of the power switch is connected to a fast shutdown circuit, which is connected to the power-on spark-proof soft-start circuit;

[0011] When the power switch is turned on, the COM pin of the power switch is connected to pin 3 of the power switch;

[0012] When the power switch is turned off, the COM pin of the power switch is connected to pin 1 of the power switch.

[0013] As a preferred solution, the fast shutdown circuit includes a resistor Rc, a resistor Rd, a transistor U2 and a resistor Re;

[0014] The resistor Rc and the resistor Rd are connected in series, the non-series node of the resistor Rc is used to connect to the power supply, the non-series node of the resistor Rd is connected to the base of the transistor U2, and the emitter of the transistor U2 is respectively connected to the non-series node of the resistor Rd and the startup anti-spark soft start circuit;

[0015] The collector of the transistor U2 is connected to the power-on spark-proof soft-start circuit through the resistor Re, and the series node of the resistor Rc and the resistor Rd is connected to the pin 1 of the power switch.

[0016] As a preferred solution, the startup anti-spark soft start circuit includes a capacitor Ca, a resistor Ra, a resistor Ri and a MOS tube U1;

[0017] The gate of the MOS tube U1 is connected to pin 3 of the power switch through the resistor Ri. The fast shutdown circuit is connected to the source of the MOS tube U1. The source of the MOS tube U1 is connected to pin 3 of the power switch through the resistor Ra. The capacitor Ca is connected in parallel with the resistor Ra. The drain of the MOS tube U1 is used to connect to the load equivalent circuit.

[0018] As a preferred solution, it further includes a power interface for connecting to a power source, and the power interface is connected to the rapid shutdown circuit.

[0019] Compared with the prior art, the present invention has obvious advantages and beneficial effects. Specifically, the rapid shutdown circuit is located between the startup spark prevention soft start circuit and the power supply, and the COM pin of the power switch is grounded through a resistor Rb, the pin 3 of the power switch is connected to the startup spark prevention soft start circuit, and the pin 1 of the power switch is connected to the rapid shutdown circuit. This can simultaneously solve the problems of instantaneous sparking at startup and long shutdown time, thereby greatly improving the user experience.

[0020] Secondly, when the power switch is turned off, transistor U2 in the fast shutdown circuit discharges the gate voltage of MOS tube U1 in the startup spark prevention soft start circuit. This improves the problem of traditional soft start circuits where MOS tube U1 cannot be turned off immediately when the switch is turned off, resulting in slow shutdown.

[0021] In addition, the overall structural design is ingenious, and the performance of each circuit is stable, safe and reliable.

[0022] In order to more clearly illustrate the structural features and effects of the present invention, it is described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a traditional power switch circuit diagram;

[0024] Figure 2 This is another traditional power switch circuit diagram with a soft start circuit;

[0025] Figure 3 This is a circuit diagram of an embodiment of the present utility model;

[0026] Figure 4 This is a voltage change diagram of the power switch circuit structure of the card reader in the embodiment of the present invention when the machine is on or off (mainly showing the voltage changes of VB, VG and VCC_DCin).

[0027] Description of Figure Numbers:

[0028] 11. Power interface

[0029] 12. Rapid shutdown circuit

[0030] 13. Start-up anti-spark soft start circuit

[0031] 14. Load equivalent circuit

[0032] 15. Power switch. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] like Figure 3 and Figure 4 As shown, a power switch circuit structure of a card reader includes a power switch 15, a power interface 11 for connecting to a power source Va, a fast shutdown circuit 12 for connecting to the power source Va, and a power-on spark-proof soft start circuit 13 for connecting to a load equivalent circuit 14;

[0035] The power interface 11 is connected to the fast shutdown circuit 12, the COM pin of the power switch 15 is grounded through the resistor Rb, the pin 3 of the power switch 15 is connected to the startup spark prevention soft start circuit 13, the pin 1 of the power switch 15 is connected to the fast shutdown circuit 12, and the fast shutdown circuit 12 is connected to the startup spark prevention soft start circuit 13;

[0036] like Figure 3 As shown, in this embodiment, the fast shutdown circuit 12 includes a resistor Rc, a resistor Rd, a transistor U2 and a resistor Re;

[0037] The resistor Rc and the resistor Rd are connected in series, the non-series node of the resistor Rc is used to connect to the power supply Va, the non-series node of the resistor Rd is connected to the base of the transistor U2, and the emitter of the transistor U2 is respectively connected to the non-series node of the resistor Rd and the startup anti-spark soft start circuit 13;

[0038] The collector of transistor U2 is connected to the spark-proof soft start circuit 13 via resistor Re, and the series connection node of resistors Rc and Rd is connected to pin 1 of power switch 15. As shown in the figure, the series connection node of resistors Rc and Rd is node VB.

[0039] In this embodiment, the startup spark prevention soft start circuit 13 includes a capacitor Ca, a resistor Ra, a resistor Ri and a MOS tube U1;

[0040] The gate of MOS transistor U1 is connected to pin 3 of power switch 15 via resistor Ri. Fast shutdown circuit 12 is connected to the source of MOS transistor U1. The source of MOS transistor U1 is connected to pin 3 of power switch 15 via resistor Ra. Capacitor Ca is connected in parallel with resistor Ra. The drain of MOS transistor U1 is connected to load equivalent circuit 14. The drain of MOS transistor U1 outputs the VCC_DCin voltage terminal.

[0041] like Figure 3 and Figure 4 As shown, when power switch 15 is turned on (from off to on at time t1), the COM pin of power switch 15 is connected to pin 3 of power switch 15. First, node VB maintains power supply Va, and transistor U2 is turned off and inactive. Next, the previously high gate voltage VG of MOS transistor U1 discharges through resistor Rb. Due to the effect of capacitor Ca, the discharge is slowed, and the gate voltage VG of MOS transistor U1 slowly decreases until, at time t2, the gate voltage VG of transistor U2 drops from power supply Va to Va*Rb / (Ra+Rb). The gate voltage VG of MOS transistor U1 slowly changes, gradually opening the channel of transistor U2.

[0042] Because the channel of transistor U2 is slowly opened, the voltage at the VCC_DCin voltage terminal slowly rises (from t1 to t2), and the power consumption of the system load equivalent circuit 14 also slowly increases. This solves the problem of instantaneous large inrush current caused by the instantaneous switching of the subsequent stage voltage and the instantaneous short circuit of the subsequent stage equalization capacitor in the traditional circuit.

[0043] like Figure 3 and Figure 4 As shown, when the power switch 15 is turned off (from on to off at time t3 ), the COM pin of the power switch 15 is connected to the pin 1 of the power switch 15 .

[0044] Due to the instantaneous discharge of resistor Rb, the VB node drops from the original power supply Va to Va*Rb / (Ra+Rb). At this time, transistor U2 turns on. Power supply Va rapidly charges the gate voltage VG of MOS transistor U1 through transistor U2 with the current of IC until time t4. When the gate voltage VG reaches power supply Va, IC also has zero current. This rapid charging process causes MOS transistor U1 to quickly turn off, causing the VCC_DCin voltage terminal to drop to zero in a short time (t3 to t4), achieving the purpose of rapid shutdown.

[0045] The key point of the design of this utility model is that it mainly solves the problems of instantaneous sparks at startup and long shutdown time by placing the fast shutdown circuit between the startup anti-spark soft start circuit and the power supply, and connecting the COM pin of the power switch to ground through a resistor Rb, connecting pin 3 of the power switch to the startup anti-spark soft start circuit, and connecting pin 1 of the power switch to the fast shutdown circuit, thereby greatly improving the user experience.

[0046] Secondly, when the power switch is turned off, transistor U2 in the fast shutdown circuit discharges the gate voltage of MOS tube U1 in the startup spark prevention soft start circuit. This improves the problem of traditional soft start circuits where MOS tube U1 cannot be turned off immediately when the switch is turned off, resulting in slow shutdown.

[0047] In addition, the overall structural design is ingenious, and the performance of each circuit is stable, safe and reliable.

[0048] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A power switch circuit structure for a card reader, characterized in that: It includes a power switch, a fast shutdown circuit for connecting to a power supply, and a startup anti-spark soft start circuit for connecting to a load equivalent circuit; The COM pin of the power switch is grounded through a resistor Rb, pin 3 of the power switch is connected to a power-on spark-proof soft-start circuit, and pin 1 of the power switch is connected to a fast shutdown circuit, which is connected to the power-on spark-proof soft-start circuit; When the power switch is turned on, the COM pin of the power switch is connected to pin 3 of the power switch; When the power switch is turned off, the COM pin of the power switch is connected to pin 1 of the power switch.

2. The power switch circuit structure of the card reader according to claim 1, characterized in that: The fast shutdown circuit includes a resistor Rc, a resistor Rd, a transistor U2 and a resistor Re; The resistor Rc and the resistor Rd are connected in series, the non-series node of the resistor Rc is used to connect to the power supply, the non-series node of the resistor Rd is connected to the base of the transistor U2, and the emitter of the transistor U2 is respectively connected to the non-series node of the resistor Rd and the startup spark prevention soft start circuit; The collector of the transistor U2 is connected to the power-on spark-proof soft-start circuit through the resistor Re, and the series node of the resistor Rc and the resistor Rd is connected to the pin 1 of the power switch.

3. The power switch circuit structure of the card reader according to claim 1, characterized in that: The startup anti-spark soft start circuit includes a capacitor Ca, a resistor Ra, a resistor Ri and a MOS tube U1; The gate of the MOS tube U1 is connected to pin 3 of the power switch through the resistor Ri. The fast shutdown circuit is connected to the source of the MOS tube U1. The source of the MOS tube U1 is connected to pin 3 of the power switch through the resistor Ra. The capacitor Ca is connected in parallel with the resistor Ra. The drain of the MOS tube U1 is used to connect to the load equivalent circuit.

4. The power switch circuit structure of the card reader according to claim 1, characterized in that: The utility model also includes a power interface for connecting a power source, and the power interface is connected to the rapid shutdown circuit.

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