Square wave signal control circuit

Abstract

The utility model discloses a square wave signal control circuit, which comprises a square wave signal input end HBSIGIN and a relay switch control circuit, the relay switch control circuit comprises an input delay circuit, a first AC-DC conversion circuit, a second AC-DC conversion circuit, a first electronic switch circuit and a second electronic switch circuit. The input end of the input time-delay circuit is connected with a square wave signal input end HBSIGIN, the first output end of the input time-delay circuit is sequentially connected with the first AC-DC conversion circuit and the first electronic switching circuit, and the second output end of the input time-delay circuit is sequentially connected with the second AC-DC conversion circuit and the second electronic switching circuit. According to the utility model, the high-frequency harmonic wave of the square wave signal can be effectively reduced, and the EMI performance of the whole circuit can be improved.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuits, and in particular to a square wave signal control circuit. Background Technology

[0002] Some existing devices use square wave signals as control signals. When a square wave signal is input, it controls the corresponding working circuit (such as a relay and a switching power supply) to work. Normally, the square wave signal is converted into a DC signal through devices such as switching transistors, diodes, and capacitors. This DC signal enables the working circuit. However, when the frequency of the square wave signal is high (such as 20kHz), the working circuit will generate high-frequency noise, which will affect the EMI performance of the entire device.

[0003] In view of the above problems, it is necessary to study a square wave signal control circuit to overcome the shortcomings of the existing technology. Utility Model Content

[0004] The purpose of this invention is to provide a square wave signal control circuit to overcome the shortcomings of the prior art.

[0005] To achieve the above objectives, the solution of this utility model is:

[0006] A square wave signal control circuit includes a square wave signal input terminal HB_SIG_IN and a relay switch control circuit. The relay switch control circuit includes an input delay circuit, a first AC-DC conversion circuit, a second AC-DC conversion circuit, a first electronic switch circuit, a second electronic switch circuit, a relay coil connection terminal Relay_CP, and a relay coil connection terminal Relay_CN. The input delay circuit includes a resistor R1, a capacitor C1, and a capacitor C2. The first end of the resistor R1 is connected to the input terminal of the input delay circuit, and the second end of the resistor R1 is connected to the first ends of the capacitors C1 and C2. The second ends of the capacitors C1 and C2 are respectively connected to the first output terminal and the second output terminal of the input delay circuit. The input terminal of the input delay circuit is connected to the square wave signal input terminal HB_SIG_IN; the input terminals of the first AC-DC conversion circuit and the second AC-DC conversion circuit are respectively connected to the first and second output terminals of the input delay circuit; the control terminals of the first and second electronic switch circuits are respectively connected to the output terminals of the first and second AC-DC conversion circuits; the input terminal of the first electronic switch circuit is connected to the drive power supply VCC; the output terminal of the second electronic switch circuit is grounded; the output terminal of the first electronic switch circuit and the input terminal of the second electronic switch circuit are respectively connected to the relay coil connection terminal Relay_CP and the relay coil connection terminal Relay_CN.

[0007] The first AC-DC conversion circuit includes resistors R6 and R7, capacitors C14 and C15, diodes D1a and D1b. The anode of diode D1a and the cathode of diode D1b are connected to the input terminal of the first AC-DC conversion circuit. The cathode of diode D1a, the first terminal of capacitor C14, the first terminal of capacitor C15, the first terminal of resistor R6, and the first terminal of resistor R7 are connected to the output terminal of the first AC-DC conversion circuit. The anode of diode D1b, the second terminal of capacitor C14, the second terminal of capacitor C15, the second terminal of resistor R6, and the second terminal of resistor R7 are grounded.

[0008] The second AC-DC conversion circuit includes resistors R8 and R9, capacitors C12 and C13, diodes D2a and D2b. The anode of diode D2a and the cathode of diode D2b are connected to the input terminal of the second AC-DC conversion circuit. The cathode of diode D2a, the first terminal of capacitor C12, the first terminal of capacitor C13, the first terminal of resistor R8, and the first terminal of resistor R9 are connected to the output terminal of the second AC-DC conversion circuit. The anode of diode D2b, the second terminal of capacitor C12, the second terminal of capacitor C13, the second terminal of resistor R8, and the second terminal of resistor R9 are grounded.

[0009] The first electronic switch circuit includes resistors R4 and R5, MOSFET Q1 and MOSFET M7. The first end of resistor R5 and the source of MOSFET Q7 are connected to the output terminal of the first electronic switch circuit. The second end of resistor R5 is connected to the first end of resistor R4 and the gate of MOSFET Q7. The second end of resistor R4 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the control terminal of the first electronic switch circuit. The drain of MOSFET Q7 is connected to the output terminal of the first electronic switch circuit.

[0010] The second electronic switch circuit includes a MOSFET Q2, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the second electronic switch circuit.

[0011] The relay switch control circuit also includes a protection circuit, which includes diodes D4 and D5. The negative terminals of diodes D4 and D5 are connected to the Relay_CP terminal of the relay control port J0, and the positive terminals of diodes D4 and D5 are connected to the Relay_CN terminal.

[0012] The square wave signal control circuit further includes a power enable circuit, which includes a third AC-DC conversion circuit, a third electronic switch circuit, and an enable terminal PFC_ON. The input terminal of the third AC-DC conversion circuit is connected to the square wave signal input terminal HB_SIG_IN, the output terminal of the third AC-DC conversion circuit is connected to the control terminal of the third electronic switch circuit, the input terminal of the third electronic switch circuit is connected to the enable terminal PFC_ON, and the output terminal of the third electronic switch circuit is grounded.

[0013] The third AC-DC conversion circuit includes resistor R23, resistor R25, capacitor C16, diode D3a, and diode D3b. The first end of resistor R23 is connected to the input terminal of the third AC-DC conversion circuit, and the second end of resistor R23 is connected to the anode of diode D3a and the cathode of diode D3b. The cathode of diode D3a, the first end of capacitor C16, and the first end of resistor R25 are connected to the output terminal of the third AC-DC conversion circuit. The anode of diode D3b, the second end of capacitor C16, and the second end of resistor R25 are grounded.

[0014] The third electronic switch circuit includes a MOS transistor Q3, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the third electronic switch circuit.

[0015] After adopting the above scheme, capacitors C1 and C2 in the input delay circuit of this utility model can play the role of high-pass filtering; moreover, capacitor C1, in combination with resistor R1, can delay the rise time of the square wave signal, thus making the rise time of the square wave signal output from the first output terminal of the input delay circuit longer. Similarly, capacitor C2, in combination with resistor R1, can delay the rise time of the square wave signal, thus making the rise time of the square wave signal output from the second output terminal of the input delay circuit longer. With this setting, both the square wave signals output from the first and second output terminals of the input delay circuit can reduce high-frequency harmonics, avoid the relay coil emitting high-frequency interference signals, and thus help improve the EMI performance of the entire circuit. Attached Figure Description

[0016] Figure 1 This is the circuit schematic diagram of this utility model.

[0017] Figure 2 This is a waveform diagram of the present invention. Detailed Implementation

[0018] To further explain the technical solution of this utility model, the following detailed description is provided through specific embodiments.

[0019] like Figure 1As shown, this utility model discloses a square wave signal control circuit, which includes a square wave signal input terminal HB_SIG_IN and a relay switch control circuit. The relay switch control circuit includes an input delay circuit, a first AC-DC conversion circuit, a second AC-DC conversion circuit, a first electronic switch circuit, a second electronic switch circuit, a relay coil connection terminal Relay_CP, and a relay coil connection terminal Relay_CN. The input terminal of the input delay circuit is connected to the square wave signal input terminal HB_SIG_IN. The input terminals of the first AC-DC conversion circuit and the second AC-DC conversion circuit are respectively connected to the first output terminal and the second output terminal of the input delay circuit. The control terminals of the first and second electronic switch circuits are respectively connected to the output terminals of the first and second AC-DC conversion circuits. The input terminal of the first electronic switch circuit is connected to the drive power supply VCC, and the output terminal of the second electronic switch circuit is grounded. The output terminal of the first electronic switch circuit and the input terminal of the second electronic switch circuit are respectively connected to the relay coil connection terminal Relay_CP and the relay coil connection terminal Relay_CN.

[0020] In use, the square wave signal input terminal HB_SIG_IN is used to receive a square wave signal, and the relay coil connection terminals Relay_CP and Relay_CN are used to connect to the two ends of the relay coil, respectively. When a square wave signal is input to the square wave signal input terminal HB_SIG_IN, the square wave signal is input to the first AC-DC conversion circuit and the second AC-DC conversion circuit through the input delay circuit. This causes the first AC-DC conversion circuit and the second AC-DC conversion circuit to output DC signals, which control the first electronic switch circuit and the second electronic switch circuit to conduct. This, in turn, energizes the relay coil connected to the relay coil connection terminals Relay_CP and Relay_CN, thereby closing the relay. When there is no signal input to the square wave signal input terminal HB_SIG_IN, the first electronic switch circuit and the second electronic switch circuit are turned off, thereby de-energizing the relay coil connected to the relay coil connection terminals Relay_CP and Relay_CN, thereby opening the relay.

[0021] In an embodiment of this utility model, the input delay circuit includes a resistor R1, a capacitor C1, and a capacitor C2. The first end of resistor R1 is connected to the input terminal of the input delay circuit, and the second end of resistor R1 is connected to the first ends of capacitors C1 and C2. The second ends of capacitors C1 and C2 are respectively connected to the first and second output terminals of the input delay circuit. Capacitors C1 and C2 can function as high-pass filters. Figure 2As shown (where line A is the signal waveform at the input terminal of the input delay circuit, line B is the signal waveform at the first output terminal of the input delay circuit, and line C is the signal waveform at the second output terminal of the input delay circuit), capacitor C1 and resistor R1 work together to delay the rise time of the square wave signal, thus making the rise time of the square wave signal output from the first output terminal of the input delay circuit longer. Similarly, capacitor C2 and resistor R1 work together to delay the rise time of the square wave signal, thus making the rise time of the square wave signal output from the second output terminal of the input delay circuit longer. This configuration reduces high-frequency harmonics in both the square wave signals output from the first and second output terminals of the input delay circuit, preventing the relay coil from emitting high-frequency interference signals, thereby helping to improve the EMI performance of the entire circuit.

[0022] In an embodiment of this utility model, the first AC-DC conversion circuit includes resistors R6 and R7, capacitors C14 and C15, diodes D1a and D1b. The anode of diode D1a and the cathode of diode D1b are connected to the input terminal of the first AC-DC conversion circuit. The cathode of diode D1a, the first terminal of capacitor C14, the first terminal of capacitor C15, the first terminal of resistor R6, and the first terminal of resistor R7 are connected to the output terminal of the first AC-DC conversion circuit. The anode of diode D1b, the second terminal of capacitor C14, the second terminal of capacitor C15, the second terminal of resistor R6, and the second terminal of resistor R7 are grounded.

[0023] In an embodiment of this utility model, the second AC-DC conversion circuit includes resistors R8 and R9, capacitors C12 and C13, diodes D2a and D2b. The anode of diode D2a and the cathode of diode D2b are connected to the input terminal of the second AC-DC conversion circuit. The cathode of diode D2a, the first terminal of capacitor C12, the first terminal of capacitor C13, the first terminal of resistor R8, and the first terminal of resistor R9 are connected to the output terminal of the second AC-DC conversion circuit. The anode of diode D2b, the second terminal of capacitor C12, the second terminal of capacitor C13, the second terminal of resistor R8, and the second terminal of resistor R9 are grounded.

[0024] In an embodiment of this invention, the first electronic switch circuit includes resistors R4 and R5, MOSFET Q1, and MOSFET M7. The first terminal of resistor R5 and the source of MOSFET Q7 are connected to the output terminal of the first electronic switch circuit. The second terminal of resistor R5 is connected to the first terminal of resistor R4 and the gate of MOSFET Q7. The second terminal of resistor R4 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the control terminal of the first electronic switch circuit. The drain of MOSFET Q7 is connected to the output terminal of the first electronic switch circuit. When the first AC-DC conversion circuit outputs a DC signal, MOSFET Q1 is turned on, causing MOSFET Q7 to turn on, thereby turning on the first electronic switch circuit.

[0025] In an embodiment of this invention, the second electronic switch circuit includes a MOSFET Q2, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the second electronic switch circuit. When the second AC-DC conversion circuit outputs a DC signal, the MOSFET Q2 is turned on, thereby turning on the second electronic switch circuit.

[0026] In an embodiment of this utility model, the relay switch control circuit further includes a protection circuit, which includes diodes D4 and D5. The negative terminals of diodes D4 and D5 are connected to the Relay_CP terminal of the relay control port J0, and the positive terminals of diodes D4 and D5 are connected to the Relay_CN terminal. Diodes D4 and D5 can dissipate the reverse electromotive force generated by the relay coil, thereby protecting the circuit.

[0027] In embodiments of this invention, the square wave signal control circuit may further include a power enable circuit, which controls whether the switching power supply operates. The power enable circuit includes a third AC-DC conversion circuit, a third electronic switch circuit, and an enable terminal PFC_ON. The input terminal of the third AC-DC conversion circuit is connected to the square wave signal input terminal HB_SIG_IN, and the output terminal of the third AC-DC conversion circuit is connected to the control terminal of the third electronic switch circuit. The input terminal of the third electronic switch circuit is connected to the enable terminal PFC_ON, and the output terminal of the third electronic switch circuit is grounded. When a square wave signal is input to the square wave signal input terminal HB_SIG_IN, the square wave signal is converted into a DC signal by the third AC-DC conversion circuit, controlling the third electronic switch circuit to conduct, thereby pulling down the level of the enable terminal PFC_ON, thus enabling the switching power supply to operate.

[0028] In an embodiment of this utility model, the third AC-DC conversion circuit includes resistor R23, resistor R25, capacitor C16, diode D3a, and diode D3b. The first end of resistor R23 is connected to the input terminal of the third AC-DC conversion circuit, and the second end of resistor R23 is connected to the anode of diode D3a and the cathode of diode D3b. The cathode of diode D3a, the first end of capacitor C16, and the first end of resistor R25 are connected to the output terminal of the third AC-DC conversion circuit. The anode of diode D3b, the second end of capacitor C16, and the second end of resistor R25 are grounded.

[0029] In an embodiment of this invention, the third electronic switch circuit includes a MOSFET Q3, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the third electronic switch circuit. When the third AC-DC conversion circuit outputs a DC signal, the MOSFET Q3 is turned on, thereby turning on the third electronic switch circuit.

[0030] The above embodiments and figures are not intended to limit the product form and style of this utility model. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of this utility model.

Claims

1. A square wave signal control circuit, characterized in that: This includes the square wave signal input terminal HB_SIG_IN and the relay switch control circuit; The relay switch control circuit includes an input delay circuit, a first AC-DC conversion circuit, a second AC-DC conversion circuit, a first electronic switch circuit, a second electronic switch circuit, a relay coil connection terminal Relay_CP, and a relay coil connection terminal Relay_CN; The input delay circuit includes resistor R1, capacitor C1, and capacitor C2. The first end of resistor R1 is connected to the input terminal of the input delay circuit, and the second end of resistor R1 is connected to the first ends of capacitor C1 and capacitor C2. The second ends of capacitor C1 and capacitor C2 are respectively connected to the first and second output terminals of the input delay circuit. The input terminal of the input delay circuit is connected to the square wave signal input terminal HB_SIG_IN. The input terminals of the first AC-DC conversion circuit and the second AC-DC conversion circuit are respectively connected to the first output terminal and the second output terminal of the input delay circuit. The control terminals of the first and second electronic switch circuits are respectively connected to the output terminals of the first and second AC-DC conversion circuits. The input terminal of the first electronic switch circuit is connected to the drive power supply VCC, and the output terminal of the second electronic switch circuit is grounded. The output terminal of the first and second electronic switch circuits are respectively connected to the relay coil connection terminal Relay_CP and the relay coil connection terminal Relay_CN.

2. The square wave signal control circuit as described in claim 1, characterized in that: The first AC-DC conversion circuit includes resistors R6 and R7, capacitors C14 and C15, diodes D1a and D1b. The anode of diode D1a and the cathode of diode D1b are connected to the input terminal of the first AC-DC conversion circuit. The cathode of diode D1a, the first terminal of capacitor C14, the first terminal of capacitor C15, the first terminal of resistor R6, and the first terminal of resistor R7 are connected to the output terminal of the first AC-DC conversion circuit. The anode of diode D1b, the second terminal of capacitor C14, the second terminal of capacitor C15, the second terminal of resistor R6, and the second terminal of resistor R7 are grounded.

3. The square wave signal control circuit as described in claim 1, characterized in that: The second AC-DC conversion circuit includes resistors R8 and R9, capacitors C12 and C13, diodes D2a and D2b. The anode of diode D2a and the cathode of diode D2b are connected to the input terminal of the second AC-DC conversion circuit. The cathode of diode D2a, the first terminal of capacitor C12, the first terminal of capacitor C13, the first terminal of resistor R8, and the first terminal of resistor R9 are connected to the output terminal of the second AC-DC conversion circuit. The anode of diode D2b, the second terminal of capacitor C12, the second terminal of capacitor C13, the second terminal of resistor R8, and the second terminal of resistor R9 are grounded.

4. The square wave signal control circuit as described in claim 1, characterized in that: The first electronic switch circuit includes resistors R4 and R5, MOSFET Q1 and MOSFET M7. The first end of resistor R5 and the source of MOSFET Q7 are connected to the output terminal of the first electronic switch circuit. The second end of resistor R5 is connected to the first end of resistor R4 and the gate of MOSFET Q7. The second end of resistor R4 is connected to the drain of MOSFET Q1. The source of MOSFET Q1 is grounded. The gate of MOSFET Q1 is connected to the control terminal of the first electronic switch circuit. The drain of MOSFET Q7 is connected to the output terminal of the first electronic switch circuit.

5. The square wave signal control circuit as described in claim 1 or 4, characterized in that: The second electronic switch circuit includes a MOSFET Q2, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the second electronic switch circuit.

6. The square wave signal control circuit as described in claim 1, characterized in that: The relay switch control circuit also includes a protection circuit, which includes diodes D4 and D5. The negative terminals of diodes D4 and D5 are connected to the Relay_CP terminal of the relay control port J0, and the positive terminals of diodes D4 and D5 are connected to the Relay_CN terminal.

7. The square wave signal control circuit as described in claim 1, characterized in that: It also includes a power enable circuit, which includes a third AC-DC conversion circuit, a third electronic switch circuit, and an enable terminal PFC_ON. The input terminal of the third AC-DC conversion circuit is connected to the square wave signal input terminal HB_SIG_IN, the output terminal of the third AC-DC conversion circuit is connected to the control terminal of the third electronic switch circuit, the input terminal of the third electronic switch circuit is connected to the enable terminal PFC_ON, and the output terminal of the third electronic switch circuit is grounded.

8. The square wave signal control circuit as described in claim 7, characterized in that: The third AC-DC conversion circuit includes resistor R23, resistor R25, capacitor C16, diode D3a, and diode D3b. The first end of resistor R23 is connected to the input terminal of the third AC-DC conversion circuit, and the second end of resistor R23 is connected to the anode of diode D3a and the cathode of diode D3b. The cathode of diode D3a, the first end of capacitor C16, and the first end of resistor R25 are connected to the output terminal of the third AC-DC conversion circuit. The anode of diode D3b, the second end of capacitor C16, and the second end of resistor R25 are grounded.

9. The square wave signal control circuit as described in claim 7, characterized in that: The third electronic switch circuit includes a MOS transistor Q3, whose gate, drain, and source are respectively connected to the control terminal, input terminal, and output terminal of the third electronic switch circuit.

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