Feedback signal detection circuit of transformer isolation mode

Abstract

The utility model provides a feedback signal detection circuit in a transformer isolation mode, which belongs to the technical field of electronic circuits and comprises a transformer T1, a capacitor E2, a photoelectric coupler OP1, a photoelectric coupler OP2, a judgment port AD1 and a judgment port AD2. The control end of the transformer T1 is electrically connected with the diode TVS2 and the diode VD2, the negative electrode of the diode TVS is connected with the negative electrode of the diode VD2, the capacitor E2 is connected with the resistor R58 in parallel, the positive electrode of the capacitor E2 and the positive electrode of the resistor R58 are electrically connected with the resistor R4 and the resistor R5, and the resistor R4 and the resistor R5 are electrically connected to the judgment port AD1 through the photoelectric coupler OP1 after being connected in parallel. The utility model aims to solve the problem that the existing fire-fighting module feedback detection scheme is easily interfered by external electromagnetic signals to cause misjudgment.

Description

Technical Field

[0001] The utility model belongs to the technical field of electronic circuits, and in particular relates to a feedback signal detection circuit in a transformer isolation mode. Background Art

[0002] The feedback detection circuit of the fire protection module is an important part of the fire protection system. It is used to monitor the status of the fire protection equipment, ensure its normal operation, and provide feedback signals when abnormalities occur. When designing the feedback detection circuit, the reliability, stability and anti-interference ability of the circuit must be considered.

[0003] The feedback detection circuit of the old version of the fire protection module (NT8254\NT8259\NT8259B\NT8259C) directly connects the feedback loop to the circuit of the module, and then detects the voltage value of the feedback loop to judge the status of the feedback loop. This connection method is easily interfered by external electromagnetic signals and causes misjudgment. Utility Model Content

[0004] The purpose of the utility model is to provide a feedback signal detection circuit in a transformer isolation mode. The utility model aims to solve the problem that the existing fire module feedback detection scheme is easily interfered by external electromagnetic signals and causes misjudgment.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] A transformer-isolated feedback signal detection circuit is used to detect current in a feedback loop, comprising: a transformer T1, a capacitor E2, a photoelectric coupler OP1, a photoelectric coupler OP2, a determination port AD1, and a determination port AD2; the control end of the transformer T1 is electrically connected to a diode TVS2 and a diode VD2 respectively, the cathode of the diode TVS is connected to the cathode of the diode VD2, the capacitor E2 is connected in parallel with a resistor R58, the positive electrodes of the capacitor E2 and the resistor R58 are electrically connected to a resistor R4 and a resistor R5, the resistor R4 and the resistor R5 are connected in parallel and then electrically connected to the determination port AD1 through the photoelectric coupler OP1, the capacitor E2 and the cathode of the resistor R58 are connected in series with the diode TVS4 and the diode VD18 in sequence and then electrically connected to the determination port AD2 through the photoelectric coupler OP2.

[0007] As a preferred solution of the utility model, the cathode of the light-emitting diode of the photoelectric coupler OP1 is connected to the anode of the light-emitting diode of the photoelectric coupler OP2, the connecting end of the photoelectric coupler OP1 and the photoelectric coupler OP2 is electrically connected to the resistor R6, and the other end of the resistor R6 is connected to the anode of the diode VD18.

[0008] As a preferred solution of the utility model, a diode VD4 is connected in series between the anode of the light emitting diode of the photoelectric coupler OP1 and the cathode of the light emitting diode of the photoelectric coupler OP2.

[0009] As a preferred solution of the utility model, the output ends of the photoelectric coupler OP1 and the photoelectric coupler OP2 are connected in parallel with capacitors C30 and C31 respectively and then grounded.

[0010] As a preferred solution of the utility model, the determination port AD1 is connected in series with a resistor R8 and then electrically connected to the VCC terminal, and the determination port AD2 is connected in series with a resistor R9 and then electrically connected to the VCC terminal.

[0011] As a preferred solution of the utility model, end 1 of the transformer T1 is electrically connected to end C of the transistor N1, end B of the transistor N1 is electrically connected to end TEST after being connected in series with resistor R10, end E of the transistor N1 is grounded, and resistor R10 is also grounded through an electrically connected resistor R60.

[0012] Compared with the prior art, the beneficial effects of the utility model are:

[0013] By designing a feedback signal detection circuit with transformer isolation, it is connected to the feedback detection loop of the fire protection module, and the state of the feedback circuit is detected every 1.2 seconds. The specific detection method is to output a voltage signal to the feedback loop every 1.2 seconds, and then detect the current in the feedback loop to determine the state of the feedback circuit, thereby reducing external electromagnetic signal interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 The utility model discloses a feedback signal detection circuit of a transformer isolation mode. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the utility model in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0017] Example

[0018] See also Figure 1, the utility model provides the following technical solutions:

[0019] A transformer-isolated feedback signal detection circuit is used to detect current in a feedback loop, comprising: a transformer T1, a capacitor E2, a photocoupler OP1, a photocoupler OP2, a determination port AD1, and a determination port AD2; the control end of the transformer T1 is electrically connected to a diode TVS2 and a diode VD2 respectively, the cathode of the diode TVS is connected to the cathode of the diode VD2, the capacitor E2 is connected in parallel to a resistor R58, the positive electrodes of the capacitor E2 and the resistor R58 are electrically connected to a resistor R4 and a resistor R5, the resistor R4 and the resistor R5 are connected in parallel and then electrically connected to the determination port AD1 through the photocoupler OP1, the capacitor E2 and the cathode of the resistor R58 are connected in series with a diode TVS4 and a diode VD18 in sequence and then electrically connected to the determination port AD2 through the photocoupler OP2, wherein the diode VD18 adopts a 1N4148 model.

[0020] Specifically, the cathode of the light emitting diode of the photocoupler OP1 is connected to the anode of the light emitting diode of the photocoupler OP2, the connecting end of the photocoupler OP1 and the photocoupler OP2 is electrically connected to the resistor R6, the other end of the resistor R6 is connected to the anode of the diode VD18, a diode VD4 is connected in series between the anode of the light emitting diode of the photocoupler OP1 and the cathode of the light emitting diode of the photocoupler OP2, the output ends of the photocoupler OP1 and the photocoupler OP2 are respectively connected in parallel with capacitors C30 and C31 and then grounded, the determination port AD1 is electrically connected to the VCC end after being connected in series with resistor R8, the determination port AD2 is electrically connected to the VCC end after being connected in series with resistor R9, the 1 end of the transformer T1 is electrically connected to the C end of the transistor N1, the B end of the transistor N1 is electrically connected to the TEST end after being connected in series with resistor R10, the E end of the transistor N1 is grounded, and the resistor R10 is also grounded through an electrical connection to resistor R60.

[0021] In specific applications, when testing, the TEST terminal is a 21K frequency PWM square wave with a duty cycle of 50%, driving the transistor N1 to generate a square wave at the primary of the transformer T1, and coupling energy to the detection circuit through the transformer T1 to charge the capacitor E2. After the delay until the voltage of the capacitor E2 is stable, the judgment is made at the judgment port AD1 and the judgment port AD2. When the A1 and A2 terminals are open, there is no current in the loop, the photocoupler OP1 and the photocoupler OP2 are not turned on, and the judgment port AD1 and the judgment port AD2 are both high level; when the A1 and A2 terminals are connected to 100K, the current in the loop is small, the photocoupler OP1 is turned on, but the voltage across R6 is not enough to turn on the photocoupler OP2, and the judgment port AD1 is low level and the judgment port AD2 is high level; when the A1 and A2 terminals are short-circuited, the current in the loop is large, the photocoupler OP1 is turned on, the voltage across the resistor R6 also reaches the turn-on voltage of the photocoupler OP2, and the judgment port AD1 and the judgment port AD2 are low level, and the model of the transistor N1 is VT-MMB5551.

[0022] Finally, it should be noted that the above description is only a preferred embodiment of the utility model and is not intended to limit the utility model. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A transformer-isolated feedback signal detection circuit for detecting a current in a feedback loop, characterized in that: The invention comprises: a transformer T1, a capacitor E2, an optocoupler OP1, an optocoupler OP2, a determination port AD1 and a determination port AD2; the control end of the transformer T1 is electrically connected to a diode TVS2 and a diode VD2 respectively, the cathode of the diode TVS is connected to the cathode of the diode VD2, the capacitor E2 is connected in parallel with a resistor R58, the anodes of the capacitor E2 and the resistor R58 are electrically connected to a resistor R4 and a resistor R5, the resistor R4 and the resistor R5 are connected in parallel and then electrically connected to the determination port AD1 through the optocoupler OP1, the capacitor E2 and the cathode of the resistor R58 are connected in series with a diode TVS4 and a diode VD18 in sequence and then electrically connected to the determination port AD2 through the optocoupler OP2.

2. The feedback signal detection circuit of a transformer isolation method according to claim 1, characterized in that: The cathode of the light emitting diode of the photocoupler OP1 is connected to the anode of the light emitting diode of the photocoupler OP2. The connecting end of the photocoupler OP1 and the photocoupler OP2 is electrically connected to the resistor R6. The other end of the resistor R6 is connected to the anode of the diode VD18.

3. The feedback signal detection circuit of a transformer isolation method according to claim 1, characterized in that: A diode VD4 is connected in series between the anode of the light emitting diode of the photocoupler OP1 and the cathode of the light emitting diode of the photocoupler OP2.

4. The feedback signal detection circuit of a transformer isolation method according to claim 3, characterized in that: The output ends of the photoelectric coupler OP1 and the photoelectric coupler OP2 are connected in parallel to capacitors C30 and C31 respectively and then grounded.

5. The feedback signal detection circuit of transformer isolation method according to claim 4, characterized in that: The determination port AD1 is electrically connected to the VCC terminal after being connected in series with a resistor R8, and the determination port AD2 is electrically connected to the VCC terminal after being connected in series with a resistor R9.

6. The feedback signal detection circuit of transformer isolation method according to claim 5, characterized in that: Terminal 1 of the transformer T1 is electrically connected to terminal C of the transistor N1, terminal B of the transistor N1 is electrically connected to terminal TEST after being connected in series with resistor R10, terminal E of the transistor N1 is grounded, and the resistor R10 is also electrically connected to ground via resistor R60.

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