CN210350770U - Overcurrent protection device - Google Patents

Abstract

The utility model discloses an overcurrent protection device, which at least comprises a power supply circuit provided with a power output terminal and a signal output terminal; a detection circuit provided with a first resistor, a second resistor and a triode; a control circuit provided with a control chip; There is a third resistor and a turn-off line of the field effect transistor; the signal output end of the power supply line is connected to the first resistor, the first resistor is connected to the emitter of the triode and then grounded; the second resistor is connected in parallel with the first resistor, and the second resistor is connected to the triode The base of the triode, the collector of the triode is connected to the trigger signal input pin of the control chip, the output end of the control chip is connected in series with a third resistor, the third resistor is connected to the gate of the field effect transistor, the source of the field effect transistor is grounded, and the power output is connected to the drain of the field effect transistor . When the power supply line outputs the signal, it flows to the control line through the detection line. When the voltage of the output pin is higher than the reference voltage of the control chip, the output pin outputs a high level, which turns on the FET of the turn-off device, thereby turning off the driver circuit. .

Description

An overcurrent protection device

technical field

The utility model relates to the technical field of dimmer circuits, in particular to an overcurrent protection device.

Background technique

In the prior art, the driver is used as an accessory in combination with LED lamps, because the driver itself does not have the matching dimming function, that is, it cannot be used with a dimmer such as a thyristor during normal operation, because the end users are mostly installed in the home circuit. If the dimmer is installed, once the driver is used with the LED lamp in the circuit of the thyristor and other dimmers, when the dimmer is adjusted to a certain gear, it will cause abnormal damage to the LED driver, high temperature, and even the danger of fire. .

The actual measurement found that when the dimmer is used, when the dimmer is adjusted to a certain level of brightness, the input current will increase greatly, which will cause the input related devices of the driver to be unable to withstand this current and cause heat damage. In severe cases, there is a risk of fire.

Utility model content

The purpose of the utility model is to overcome the defects in the prior art, and provide a simple structure, convenient use, and timely prevention of the problem of heat damage to the driver input related devices caused by the sharp increase of current in the dimmer circuit.

In order to achieve the above purpose, the technical solution of the present utility model is to design an overcurrent protection device, the overcurrent protection device at least includes a power supply line provided with a power output end and a signal output end; The detection circuit of the triode; the control circuit of the control chip is provided; the turn-off circuit of the third resistor and the field effect transistor is provided; the signal output end of the power supply circuit is connected to the first resistor, and the first resistor is connected to the emitter of the triode and then grounded; The second resistor is connected in parallel with the first resistor, the second resistor is connected to the base of the triode, the collector of the triode is connected to the trigger signal input pin of the control chip, the output end of the control chip is connected in series with a third resistor, the third resistor is connected to the gate of the field effect transistor, and the field The source of the effect transistor is grounded, and the power output is connected to the drain of the field effect transistor. When a signal is input in the line, the input current generates an induced voltage on the first resistor, and the induced voltage is limited by the second resistor and then input to the base of the triode. When the induced voltage reaches the turn-on voltage of the triode, the triode is turned on. At this time, the voltage of the input pin of the control chip is pulled down to the ground, and the voltage signal of the input pin of the control chip changes from high level to low level. After the internal circuit of the control chip detects that the voltage of the input pin changes from a high level to a low level, the output pin of the control chip outputs a high-level control voltage signal, and this high-level signal is limited by the third resistor connected in series with the output terminal. After that, input to the gate of the FET that turns off the device. When the high-level control voltage signal reaches the turn-on voltage of the FET, the FET is turned on. At this time, the power output pin in the power supply line is short-circuited to the ground, and the power supply voltage is 0V, thereby turning off the power conversion output of the driver circuit. . At this time, there is no normal power output, that is, there will be no large current generated in the input circuit.

In order to be applicable to different products, a further preferred technical solution is that the power output of the power supply line in the overcurrent protection device is connected to the anode of the first diode, and the cathode of the first diode is connected to one end of the first capacitor , the other end of the first capacitor is grounded.

In order to be suitable for different products, a further preferred technical solution is that the cathode of the first diode in the overcurrent protection device is connected to one end of the fourth resistor, and the other end of the fourth resistor is respectively connected to the input pin of the control chip and the triode the collector.

In order to be applicable to different products, a further preferred technical solution is that the cathode of the first diode in the overcurrent protection device is connected to the power supply pin of the control chip.

In order to be applicable to different products, a further preferred technical solution is that the cathode of the first diode in the overcurrent protection device is connected to the reset pin of the control chip.

In order to be applicable to different products, a further preferred technical solution is that the cathode of the first diode in the overcurrent protection device is connected in series with a fifth resistor, and the fifth resistor is connected to the threshold pin of the control chip; the fifth resistor is also connected to the The anode of the second diode is connected to the drain of the field effect transistor.

In order to be suitable for different products, a further preferred technical solution is that the control chip in the overcurrent protection device is provided with a control voltage pin, which is connected in series with the second capacitor, and the other end of the second capacitor is grounded.

In order to be applicable to different products, a further preferred technical solution is that the power input of the power supply line in the overcurrent protection device is grounded and/or the control chip is grounded.

In order to be applicable to different products, a further preferred technical solution is that the triode of the detection circuit in the overcurrent protection device is of NPN type.

In order to be applicable to different products, a further preferred technical solution is that the model of the control chip in the overcurrent protection device is TS555MD.

When a signal is input in the line, it flows to the control line through the detection line. When the output pin voltage is higher than the reference voltage of the control chip, the output pin outputs a high level, which will turn off the device and turn off the driver circuit. When the power supply voltage of the control chip drops to the restart voltage threshold of the control chip, the control signal of the control chip is reset, the field effect transistor is turned off, and the driver circuit is restarted and ready to enter the next working cycle.

Description of drawings

1 is a schematic diagram of an overcurrent protection device of the present invention;

Detailed ways

The specific embodiments of the present utility model will be further described below with reference to the accompanying drawings and embodiments. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

As shown in FIG. 1, the present utility model is an overcurrent protection device, and the overcurrent protection device includes a power supply circuit formed with a power output end, a signal output end, a first diode D7, and a first capacitor C9; A detection circuit composed of a first resistor RS1, a second resistor R14 and an NPN transistor Q2 is provided; a control chip U1, a fourth resistor R11, a fifth resistor R12, a second diode D8, and a second capacitor C10 are provided for control circuit; a turn-off circuit composed of a third resistor R13 and a field effect transistor Q1 is provided.

The signal output end of the power supply line is connected to the first resistor RS1, the first resistor RS1 is connected to the emitter of the NPN transistor Q2 and then grounded; the second resistor R14 is connected in parallel with the first resistor RS1, and the second resistor R14 is connected to the base of the NPN transistor Q2, The collector of the NPN transistor Q2 is connected to the trigger signal input pin 2 of the control chip U1, the output pin 3 of the control chip U1 is connected to the gate of the field effect transistor Q1 through the third resistor R13 connected in series, the source electrode of the field effect transistor Q1 is grounded, and the field effect transistor Q1 The drain is connected to the output terminal of the power supply; the output terminal of the power supply is connected to the anode of the first diode D7, the cathode of D7 is connected to one end of the first capacitor C9, and the other end of the first capacitor C9 is grounded; the cathode of the first diode D7 is connected to the fourth resistor One end of R11 and the other end of the fourth resistor R11 are respectively connected to the trigger signal input pin 2 of the control chip U1 and the collector of the NPN transistor Q2; the cathode of the first diode D7 is connected to the power supply pin 8 of the control chip; the first diode D7 The negative electrode is connected to the reset pin 4 of the control chip; the negative electrode of the first diode D7 is connected in series with one end of the fifth resistor R12, and the other end of the fifth resistor R12 is connected to the threshold pin 6 of the control chip; the fifth resistor R12 is also connected to the second diode D8 The anode, the cathode of the second diode D8 is connected to the drain of the field effect transistor Q1. At the same time, the control chip U1 is provided with a control voltage pin 5, which is grounded through the second capacitor C10 connected in series; the power supply of the power supply line is grounded, and the control chip is grounded; the power output of the power supply line is connected to an external dimmer circuit.

When a signal is input to the overcurrent protection device, an induced voltage is generated on the first resistor RS1, and the induced voltage is limited by R14 and then input to the base of the NPN transistor Q2. When the induced voltage reaches the conduction voltage of the transistor Q2, the transistor Q2 Turn on, at this time, the voltage of the trigger signal input pin 2 of the control chip U1 is pulled down to the ground, and the voltage signal of the trigger signal input pin 2 of the U1 chip is changed from high level to low level. After the internal circuit of the U1 chip detects that the voltage signal of the trigger signal input pin 2 changes from high level to low level, a high level control voltage signal is output through output pin 3. After the signal is limited by the third resistor R13, it is input to the Turn off the gate of the device field effect transistor Q1, when the high-level control voltage signal reaches the conduction voltage of the field effect transistor Q1, the field effect transistor Q1 is turned on, and the voltage of the power supply pin is pulled down to the ground at this time. When the FET Q1 is turned on, the power supply pin is short-circuited to the ground, the power supply voltage is 0V, and the driver chip in the dimmer circuit cannot obtain a stable voltage supply, so that the power supply voltage of the input pin of the driver chip is under-voltage and enters the protection state, thereby Turn off the power conversion output of the driver circuit. At this time, there is no normal power output, that is, there will be no large current generated in the input circuit. Until the power supply voltage of pin 8 of the control chip U1 in the overcurrent protection circuit drops to the restart voltage threshold of the control chip, the control signal of the output pin 3 of the control chip U1 is reset, the field effect transistor Q1 is turned off, and the driver circuit restarts and prepares to enter the next step. a working cycle.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the technical principles of the present invention, several improvements and modifications can be made. These improvements and retouching should also be regarded as the protection scope of the present invention.

Claims (10)

1. An overcurrent protection device is characterized by at least comprising a power supply circuit provided with a power supply output end and a signal output end; the detection circuit is provided with a first resistor, a second resistor and a triode; a control circuit provided with a control chip; a turn-off circuit provided with a third resistor and a field effect tube; the signal output end of the power supply line is connected with a first resistor, and the first resistor is grounded after being connected with the emitting electrode of the triode; the second resistor is connected with the first resistor in parallel, the second resistor is connected with the base of the triode, the collector of the triode is connected with the trigger signal input pin of the control chip, the output end of the control chip is connected with the third resistor in series, the third resistor is connected with the grid electrode of the field-effect tube, the source electrode of the field-effect tube is grounded, and the power output is connected with the drain electrode of the field-effect tube.

2. The overcurrent protection device as claimed in claim 1, wherein the power supply line of the overcurrent protection device has a power supply output connected to the anode of a first diode, the cathode of the first diode is connected to one end of a first capacitor, and the other end of the first capacitor is grounded.

3. The over-current protection device as claimed in claim 2, wherein a cathode of the first diode in the over-current protection device is connected to one end of a fourth resistor, and the other end of the fourth resistor is connected to the input pin of the control chip and the collector of the triode, respectively.

4. The over-current protection device as claimed in claim 3, wherein the negative electrode of the first diode in the over-current protection device is connected to the power supply pin of the control chip.

5. The over-current protection device as claimed in claim 4, wherein the negative electrode of the first diode in the over-current protection device is connected to the reset pin of the control chip.

6. The over-current protection device as claimed in claim 5, wherein a negative electrode of the first diode in the over-current protection device is connected in series with a fifth resistor, and the fifth resistor is connected with a threshold pin of the control chip; the fifth resistor is also connected with the anode of a second diode, and the cathode of the second diode is connected with the drain of the field effect transistor.

7. The over-current protection device as claimed in claim 6, wherein the control chip of the over-current protection device is provided with a control voltage pin connected in series with the second capacitor, and the other end of the second capacitor is grounded.

8. The over-current protection device as claimed in claim 1, wherein the power supply output of the power supply line and/or the control chip in the over-current protection device is grounded.

9. The overcurrent protection device as recited in claim 1, wherein a transistor of a detection circuit of the overcurrent protection device is NPN.

10. The overcurrent protection device as recited in claim 1, wherein the control chip in the overcurrent protection device is of type TS555 MD.

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