A driving circuit and electronic equipment

Abstract

The present application provides a driving circuit and an electronic device, which relates to the field of electronic circuit technology. The driving circuit is connected to an external device through a transmission line, wherein the driving circuit includes M driving channels, and M is an integer greater than 0. Each driving channel includes: a gating circuit, a filtering circuit, and an input / output IO interface. One end of the filtering circuit is connected to the gating circuit, and the other end of the filtering circuit is connected to the IO interface. The filtering circuit is used to filter the electrical fast transient pulse group EFT input from the IO interface. Since the filtering circuit is set in the driving circuit, the transmission line between the driving circuit and the external device is interfered by EFT. When the EFT interference is input into the driving circuit along the transmission line, the filtering circuit can filter the EFT interference to prevent EFT from affecting the performance of the driving circuit. Secondly, adding a filtering circuit to the driving circuit can enable the driving circuit to pass the EFT interference test and improve the reliability and stability of the driving circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a driving circuit and an electronic device. Background Art

[0002] The electrical fast transient (EFT) experiment is an important one among many electromagnetic compatibility (EMC) experiments. It is a relatively difficult experiment for electronic equipment to pass in the "3C" certification. EFT is a source of electromagnetic disturbance. Since the pulse group can produce an accumulation effect at the input end of the circuit, the amplitude of the disturbance level may eventually exceed the noise tolerance of the circuit. On the other hand, the period of the pulse group is short, and the interval time of each pulse wave is short. When the first pulse wave has not disappeared, the second pulse wave follows. For the input capacitor in the circuit, it starts to charge again before the discharge is completed, so it is easy to reach a higher voltage, which has a great impact on the normal operation of the circuit. When some driver chips are used to drive external devices, the driver chip and the external device need to be connected through the connection on the PCB board. The PCB board connection is easily interfered by EFT, which further transmits EFT to the driver chip, thereby affecting the performance of the driver chip. Summary of the invention

[0003] Since in the prior art, a PCB board connecting a driver chip and an external device is easily interfered by EF T, thereby further affecting the performance of the driver chip, the present application provides a driver circuit and an electronic device.

[0004] In a first aspect, an embodiment of the present application provides a driving circuit connected to an external device via a transmission line, including:

[0005] M driving channels, where M is an integer greater than 0;

[0006] Each driving channel includes: a gating circuit, a filtering circuit and an input / output IO interface;

[0007] One end of the filter circuit is connected to the gating circuit, and the other end of the filter circuit is connected to the IO interface;

[0008] The filtering circuit is used for filtering the electrical fast transient pulse group EFT input from the IO interface.

[0009] Optionally, the filter circuit is a low-pass filter circuit.

[0010] Optionally, the low-pass filter circuit includes a first resistor and a first capacitor;

[0011] One end of the first resistor is connected to the selection circuit, the other end of the first resistor is connected to the IO interface, one end of the first capacitor is connected to a node between the first resistor and the IO interface, and the other end of the first capacitor is grounded.

[0012] Optionally, a cut-off frequency of the filter circuit is less than a frequency of the EFT.

[0013] Optionally, the gating circuit includes:

[0014] N gating channels, where N is an integer greater than 0;

[0015] Each gating channel includes a gating switch and a signal source. When the gating switch is closed, the signal source outputs a driving signal to the external device.

[0016] Optionally, the N gating channels are switched according to a preset switching frequency.

[0017] Optionally, a cut-off frequency of the filter circuit is greater than a switching frequency between the N gating channels.

[0018] Optionally, the IO interface includes a first diode and a second diode;

[0019] The anode of the first diode is connected to the cathode of the second diode, the cathode of the first diode is connected to the power supply terminal, and the anode of the second diode is grounded;

[0020] The filter circuit is connected to a node between the first diode and the second diode.

[0021] In a second aspect, an embodiment of the present application provides an electronic device, including a transmission line, an external device, and the driving circuit described in the first aspect.

[0022] Optionally, the driving circuit is a liquid crystal display (LCD) driving circuit, the external device is an LCD, and the transmission line is a printed circuit board (PCB).

[0023] In an embodiment of the present application, the driving circuit is connected to an external device via a transmission line, wherein the driving circuit includes M driving channels, where M is an integer greater than 0. Each driving channel includes: a gating circuit, a filtering circuit, and an input / output IO interface. One end of the filtering circuit is connected to the gating circuit, and the other end of the filtering circuit is connected to the IO interface. The filtering circuit is used to filter the electrical fast transient pulse group EFT input from the IO interface. Since the filtering circuit is provided in the driving circuit, and the filtering circuit is located between the IO interface and the gating circuit, the transmission line between the driving circuit and the external device is interfered by EFT. When the EFT interference is input into the driving circuit along the transmission line, the filtering circuit can filter the EFT interference to prevent EFT from affecting the performance of the driving circuit. Secondly, adding a filtering circuit to the driving circuit can enable the driving circuit to pass the EFT interference test, thereby improving the reliability and stability of the driving circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of a driving circuit provided in an embodiment of the present application;

[0026] Figure 2 A schematic diagram of the structure of a driving channel provided in an embodiment of the present application;

[0027] Figure 3 A schematic diagram of the structure of a gating circuit provided in an embodiment of the present application;

[0028] Figure 4 A schematic diagram of the structure of a gating circuit provided in an embodiment of the present application;

[0029] Figure 5 A schematic diagram of a driving circuit provided in an embodiment of the present application;

[0030] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and beneficial effects 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.

[0032] Figure 1A schematic diagram of a driving circuit provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the driving circuit 100 is connected to the external device 300 through a transmission line 200, wherein the driving circuit includes M driving channels 110, where M is an integer greater than 0. Each driving channel 110 includes: a gating circuit 111, a filtering circuit 112, and an input / output IO interface 113. One end of the filtering circuit 112 is connected to the gating circuit 111, and the other end of the filtering circuit is connected to the IO interface 113. The filtering circuit 112 is used to filter the electrical fast transient pulse group EFT input from the IO interface 113. In a specific implementation, the number of driving channels 110 in the driving circuit 100 is determined according to actual conditions. Each driving channel 110 in the driving circuit 100 can be used to drive different external devices 300, and each driving channel 110 is connected to the corresponding driven external device 300 through a transmission line. The external device 300 includes but is not limited to a liquid crystal display (LCD), a microphone, and a speaker. The transmission line between the driving circuit 100 and the external device 300 may be a printed circuit board (PCB). In the PCB, each driving channel should avoid parallel routing with small spacing and large length as much as possible.

[0033] Since a filter circuit is provided in the driving circuit and the filter circuit is located between the IO interface and the gating circuit, when the transmission line between the driving circuit and the external device is interfered by EFT and the EFT interference is input into the driving circuit along the transmission line, the filter circuit can filter the EFT interference to prevent EFT from affecting the performance of the driving circuit. Secondly, adding a filter circuit to the driving circuit can enable the driving circuit to pass the EFT interference test and improve the reliability and stability of the driving circuit.

[0034] In the driving channel 110 , the filtering circuit 112 may be a low-pass filter or a band-pass filter.

[0035] Optionally, when the filter circuit 112 is a low-pass filter circuit, it includes a first resistor 1121 and a first capacitor 1122, such as Figure 2 As shown, one end of the first resistor 1121 is connected to the selection circuit 111, the other end of the first resistor 1121 is connected to the IO interface 113, one end of the first capacitor 1122 is connected to the node between the first resistor 1121 and the IO interface 113, and the other end of the first capacitor 1122 is grounded.

[0036] EFT interference is a series of pulse groups with a repetition frequency of 5KHz. The rise time of a single sub-pulse in each pulse group is 5ns and the sustain time is 50ns. Therefore, the frequency of EFT is less than 20MHz. In the EFT experiment, anti-EFT interference is divided into four levels. The voltage peak corresponding to the first level is 500V, the voltage peak corresponding to the second level is 1000V, the voltage peak corresponding to the third level is 2000V, and the voltage peak corresponding to the fourth level is 4000V. In order for the drive circuit to pass the fourth level EFT experiment, the cutoff frequency of the filter circuit is less than the EFT frequency of 20MHz, so that the EFT interference can be filtered out. In specific implementation, 10MHz, 5MHz, 1MHz, etc. can be used.

[0037] Optionally, the gating circuit 111 includes: N gating channels, where N is an integer greater than 0, such as Figure 3 As shown, each gating channel includes a gating switch 1111 and a signal source 1112. When the gating switch 1111 is closed, the signal source 1112 outputs a driving signal to the external device 300. In a specific implementation, N is set according to actual conditions. When N is an integer greater than 1, the N gating channels are switched according to a preset switching frequency, and then different driving signals are output to the external device. For example, Figure 4 As shown, N is 4, wherein the first selection channel includes a signal source VLCD and a switch SW0, the second selection channel includes a signal source 2 / 3VLCD and a switch SW1, the third selection channel includes a signal source 1 / 3VLCD and a switch SW2, the fourth selection channel includes a signal source VSS and a switch SW3, the filter circuit is a low-pass filter circuit, and the low-pass filter circuit is composed of a resistor R and a capacitor C, and the external device is an LCD. The voltage of the signal source VLCD is driven by a slow clock of 32kHz and is raised to the target voltage by a charge pump. The signal source 2 / 3VLCD and the signal source 1 / 3VLCD are obtained by dividing the voltage of the signal source VLCD, and the signal source VSS is grounded. The four selection switches are switched at a preset frequency to adjust the brightness of the external device LCD, wherein the switching frequency between the four selection switches is about 100Hz.

[0038] In order to allow the filter circuit to filter out the EFT interference without affecting the drive signal driving the external device, the cutoff frequency of the filter circuit is greater than the switching frequency between the N selection channels. Exemplarily, the filter circuit is set to a low-pass filter circuit, and the cutoff frequency of the low-pass filter circuit should be between 100 Hz and 20 MHz. When the cutoff frequency of the low-pass filter circuit is set to 1 MHz, the values ​​of the first resistor and the first capacitor in the low-pass filter circuit can be further determined according to the following formula (1).

[0039]

[0040] Wherein, f is the cut-off frequency of the low-pass filter circuit, R is the first resistor, and C is the first capacitor.

[0041] Specifically, when R=50kΩ and C=3.2pF, the above formula (1) can be satisfied. It should be noted that the values ​​of the first resistor and the first capacitor in the low-pass filter circuit are not limited to the above values, and any resistor and capacitor that satisfies formula (1) are acceptable, which will not be described in detail here.

[0042] Alternatively, if Figure 5 As shown, the IO interface 113 includes a first diode 1131 and a second diode 1132. The anode of the first diode 1131 is connected to the cathode of the second diode 1132, the cathode of the first diode 1131 is connected to the power supply terminal, and the anode of the second diode 1132 is grounded. The filter circuit 112 is connected to the node between the first diode 1131 and the second diode 1132.

[0043] The present application embodiment provides a structural example diagram of an electronic device, such as Figure 6 As shown, the invention comprises a driving circuit 100 , a transmission line 200 and an external device 300 .

[0044] Optionally, the driving circuit 100 is a liquid crystal display (LCD) driving circuit, the external device 300 is an LCD, and the transmission line 200 is a printed circuit board (PCB).

[0045] Since a filter circuit is provided in the driving circuit and the filter circuit is located between the IO interface and the gating circuit, when the transmission line between the driving circuit and the external device is interfered by EFT and the EFT interference is input into the driving circuit along the transmission line, the filter circuit can filter the EFT interference to prevent EFT from affecting the performance of the driving circuit. Secondly, adding a filter circuit to the driving circuit can enable the driving circuit to pass the EFT interference test and improve the reliability and stability of the driving circuit.

[0046] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A driving circuit connected to an external device via a transmission line, characterized in that: include: M driving channels, where M is an integer greater than 0; Each driving channel includes: a gating circuit, a filtering circuit and an input / output IO interface; One end of the filter circuit is connected to the gating circuit, and the other end of the filter circuit is connected to the IO interface; The filtering circuit is used to filter the electrical fast transient pulse group EFT input from the IO interface; The gating circuit comprises: N gating channels, where N is an integer greater than 0; Each gating channel includes a gating switch and a signal source, and when the gating switch is closed, the signal source outputs a driving signal to the external device; The filter circuit is a low-pass filter circuit.

2. The driving circuit according to claim 1, characterized in that: The low-pass filter circuit includes a first resistor and a first capacitor; One end of the first resistor is connected to the selection circuit, the other end of the first resistor is connected to the IO interface, one end of the first capacitor is connected to a node between the first resistor and the IO interface, and the other end of the first capacitor is grounded.

3. The driving circuit according to claim 1 or 2, characterized in that: The cut-off frequency of the filter circuit is lower than the frequency of the EFT.

4. The driving circuit according to claim 1, wherein: The N gating channels are switched according to a preset switching frequency.

5. The driving circuit according to claim 4, characterized in that: The cut-off frequency of the filter circuit is greater than the switching frequency between the N gating channels.

6. The driving circuit according to claim 1, characterized in that: The IO interface includes a first diode and a second diode; The anode of the first diode is connected to the cathode of the second diode, the cathode of the first diode is connected to the power supply terminal, and the anode of the second diode is grounded; The filter circuit is connected to a node between the first diode and the second diode.

7. An electronic device, characterized in that: It comprises a transmission line, an external device and the driving circuit according to any one of claims 1 to 6.

8. The electronic device according to claim 7, characterized in that: The driving circuit is a liquid crystal display (LCD) driving circuit, the external device is an LCD, and the transmission line is a printed circuit board (PCB).

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