CN204559093U - Current foldback circuit and television set - Google Patents
Current foldback circuit and television set Download PDFInfo
- Publication number
- CN204559093U CN204559093U CN201520265627.XU CN201520265627U CN204559093U CN 204559093 U CN204559093 U CN 204559093U CN 201520265627 U CN201520265627 U CN 201520265627U CN 204559093 U CN204559093 U CN 204559093U
- Authority
- CN
- China
- Prior art keywords
- current
- circuit
- operational amplifier
- input end
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000005070 sampling Methods 0.000 claims abstract description 64
- 239000003990 capacitor Substances 0.000 claims description 52
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052710 silicon Inorganic materials 0.000 claims description 10
- 239000010703 silicon Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 230000010354 integration Effects 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 abstract 6
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Landscapes
- Emergency Protection Circuit Devices (AREA)
Abstract
The utility model discloses a kind of current foldback circuit, this current foldback circuit comprises power input, transformer, current-doubling rectifier, peak current protective circuit, average current protective circuit, overcurrent protection executive circuit and the current sampling circuit for sampling the electric current of load; Power input is connected with the former limit of transformer, and the secondary of transformer is connected with load through current-doubling rectifier; The sampling end of current sampling circuit is connected with current-doubling rectifier, and the output of current sampling circuit is connected with the input of peak current protective circuit and the input of average current protective circuit respectively; The output of peak current protective circuit and the output of average current protective circuit are all connected with the input of overcurrent protection executive circuit; The output of overcurrent protection executive circuit is connected with the Enable Pin of power input.The utility model can not only carry out overcurrent protection to the peak current of load, and can also carry out overcurrent protection to the average current of load.
Description
Technical Field
The utility model relates to a TV set technical field, in particular to overcurrent protection circuit and TV set.
Background
At present, because LED lamps have the advantages of long service life, power saving, energy saving and convenient driving, more and more LCD color tvs use LED lamps as their backlight lamps, and the existing LED backlight schemes generally have two kinds: one is direct type, that is, a plurality of LED lamps are directly arranged behind an LCD screen of a television; the other type is a side-in type, namely a plurality of LED lamps are respectively arranged at the periphery of an LCD screen of the television, and then the light of the LED lamps is uniformly guided to the whole LCD screen through a light guide plate. The two LED backlight schemes are commonly used, however, the direct-type LED backlight scheme has more advantages, and the main advantage is that the local dimming function of the LCD screen can be realized, the so-called local dimming function is to divide a plurality of LED lamps behind the LCD screen into a plurality of lamp groups, for example, into 32 groups, 64 groups or 128 groups, each group is composed of a plurality of LED lamps in series, and if the number of the groups is larger, the backlight effect is better. The brightness of each lamp group is determined by the brightness of the picture, namely, the direct type LED backlight scheme can enable the display effect of the picture to be better, and more energy and electricity can be saved.
However, in the direct-type LED backlight scheme, if there are 128 groups of lamps, 128 power supplies are needed to drive the lamps, in the prior art, in order to reduce the number of driving inverters, several lamp groups usually share one driving inverter, for example, 128 lamp groups use 8 driving inverters, and in order to reduce interference, these driving inverters usually operate at the same frequency and the same phase, which has the disadvantage that the simultaneous switching of power devices of these driving inverters not only generates a large electromagnetic interference, but also increases ripple current of an input capacitor, thereby reducing the lifetime, in order to improve efficiency, the output voltage of the power supply is about twice as much as the driving output voltage, if the current of one LED lamp is 0.3A, the total current of 128 LED lamps (in the prior art, the number of backlight lamps of a 55-inch LCD panel is 128) will reach 38.4A, without driving loss, the output current of the power supply will reach 19.2A, and the loss of actual driving is also large (about 20% -30% of output power), so the output current of the power supply is larger than 19.2A, and as the size of the LCD screen increases, the number of LED lamps increases, so that the output current of the power supply will be larger, and such large current will make the overcurrent protection of the power supply board become a big problem,
referring to fig. 1, fig. 1 is a schematic circuit structure diagram of an embodiment of an overcurrent protection circuit in the prior art. The over-current protection circuit includes a power supply 301 for providing a power supply voltage to the second load 400, a sampling resistor RS, a fifth operational amplifier OP5, a sixth operational amplifier OP6, and a fourth reference voltage source Vref 4. The output end of the power supply 301 is connected to the first end of the second load 400 through the sampling resistor RS, and the second end of the second load 400 and the ground end of the power supply 301 are both grounded; a non-inverting input terminal of the fifth operational amplifier OP5 is connected to the output terminal of the power supply 301, an inverting input terminal of the fifth operational amplifier OP5 is connected to the first terminal of the second load 400, and an output terminal of the fifth operational amplifier OP5 is connected to a non-inverting input terminal of the sixth operational amplifier OP 6; an inverting input terminal of the sixth operational amplifier OP6 is connected to the positive terminal of the fourth reference voltage source Vref 4; the negative pole of the fourth reference voltage source Vref4 is grounded; the output end of the sixth operational amplifier OP6 is the overcurrent protection signal output end OUT of the overcurrent protection circuit of this embodiment. In the present embodiment, the first and second electrodes are,
a sampling resistor RS is connected in series between the output terminal of the power supply 301 and the first terminal of the second load 400, the sampling resistor RS converts the current flowing through the second load 400 into a floating voltage, then the floating voltage is converted into a voltage of a ground pair through the fifth operational amplifier OP5, and finally the sixth operational amplifier OP6 compares the voltage of the ground pair with the reference voltage generated by the fourth reference voltage source Vref4 to obtain an overcurrent protection signal, and the overcurrent protection signal is output from the overcurrent protection signal output terminal OUT. However, the overcurrent protection circuit of the present embodiment has the following disadvantages: the voltage drop on the sampling resistor RS brings about loss, and assuming that the voltage drop on the sampling resistor RS is 0.5V, the loss is as high as 15W when the current is 30A; the (second) fifth operational amplifier OP5 is used to convert the floating voltage into a voltage to ground, that is, the fifth operational amplifier OP5 needs to have a strong common-mode signal rejection capability, and the operational amplifier with the strong common-mode signal rejection capability is expensive, so that the cost of the overcurrent protection circuit of the present embodiment is high; and (III) the overcurrent protection circuit of the embodiment can only carry out overcurrent protection on the peak current of the load, but cannot carry out overcurrent protection on the average current of the load.
SUMMERY OF THE UTILITY MODEL
The main objective of the present invention is to provide an overcurrent protection circuit capable of simultaneously performing overcurrent protection on the peak current and the average current of a load.
In order to achieve the above object, the present invention provides an overcurrent protection circuit, which includes a power input terminal for providing a power supply voltage for a load, a transformer for performing voltage conversion on the power supply voltage, a current doubler rectifier circuit for performing current doubler rectification on a voltage output by the transformer, a current sampling circuit for sampling a current of the load, a peak current protection circuit for performing overcurrent protection on a peak current of the load, an average current protection circuit for performing overcurrent protection on an average current of the load, and an overcurrent protection execution circuit for controlling an on-off state of the power input terminal according to an output signal of the peak current protection circuit or an output signal of the average current protection circuit to perform an overcurrent protection action on the load; wherein,
the power supply input end is connected with the primary side of the transformer, and the secondary side of the transformer is connected with the load through the current doubling rectifying circuit; the sampling end of the current sampling circuit is connected with the current doubling rectifying circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit; the output end of the peak current protection circuit and the output end of the average current protection circuit are both connected with the input end of the overcurrent protection execution circuit; and the output end of the overcurrent protection execution circuit is connected with the enable end of the power input end.
Preferably, the current-doubling rectifying circuit comprises a first inductor, a second inductor, a first diode, a second diode and an electrolytic capacitor; wherein,
the first end of the first inductor is connected with the first end of the secondary coil of the transformer, and the second end of the first inductor is grounded with the current input end of the load; the first end of the second inductor is connected with the second end of the secondary coil of the transformer, and the second end of the second inductor is connected with the second end of the first inductor; the anode of the electrolytic capacitor is connected with the current input end of the load, and the cathode of the electrolytic capacitor is grounded; the cathode of the first diode is connected with the first end of the first inductor, and the anode of the first diode is respectively connected with the anode of the second diode and the cathode of the electrolytic capacitor; and the cathode of the second diode is connected with the first end of the second inductor.
Preferably, the current sampling circuit comprises a first resistor, a second resistor, a first capacitor, a second capacitor, a third diode and a fourth diode; wherein,
a first end of the first resistor is connected with a first end of the first inductor, and a second end of the first resistor is respectively connected with a first end of the first capacitor and an anode of the third diode; the second end of the first capacitor is connected with the second end of the first inductor; the cathode of the third diode and the cathode of the fourth diode are connected to a first node, the first node is the output end of the current sampling circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit;
a first end of the second resistor is connected with a first end of the second inductor, and a second end of the second resistor is respectively connected with a first end of the second capacitor and an anode of the fourth diode; a second end of the second capacitor is connected with a second end of the second inductor; the cathode of the fourth diode is connected to the cathode of the third diode.
Preferably, the peak current protection circuit includes a first operating voltage input terminal, a first operational amplifier, and a first reference voltage source; wherein,
the non-inverting input end of the first operational amplifier is connected with the output end of the current sampling circuit, the inverting input end of the first operational amplifier is connected with the positive electrode of the first reference voltage source, the output end of the first operational amplifier is the output end of the peak current protection circuit, the output end of the peak current protection circuit is connected with the input end of the overcurrent protection execution circuit, the power supply end of the first operational amplifier is connected with the first working voltage input end, and the ground end of the first operational amplifier and the negative electrode of the first reference voltage source are both connected with the current input end of the load.
Preferably, the average current protection circuit comprises a voltage integrating circuit unit, an average current over-current comparison circuit unit and a time delay circuit unit; wherein,
the input end of the voltage integrating circuit unit is connected with the output end of the current sampling circuit, and the output end of the voltage integrating circuit unit is connected with the input end of the average current over-current comparison circuit unit; the output end of the average current over-current comparison circuit unit is connected with the input end of the delay circuit unit; and the output end of the delay circuit unit is connected with the input end of the overcurrent protection execution circuit.
Preferably, the voltage integration circuit unit includes a second operational amplifier, a third resistor and a third capacitor; wherein,
the power supply end of the second operational amplifier is connected with the first working voltage input end, the inverting input end of the second operational amplifier and the ground end of the second operational amplifier are both connected with the current input end of the load, the non-inverting input end of the second operational amplifier is connected with the output end of the current sampling circuit through the third resistor, and the output end of the second operational amplifier is connected with the input end of the average current over-current comparison circuit unit; the first end of the third capacitor is connected with the non-inverting input end of the second operational amplifier, and the second end of the third capacitor is connected with the first working voltage input end.
Preferably, the average current over-current comparison circuit unit comprises a third operational amplifier and a second reference voltage source; wherein,
the power supply end of the third operational amplifier is connected with the first working voltage input end, the ground end of the third operational amplifier is connected with the current input end of the load, the non-inverting input end of the third operational amplifier is connected with the output end of the second operational amplifier, the inverting input end of the third operational amplifier is connected with the anode of the second reference voltage source, and the output end of the third operational amplifier is connected with the input end of the delay circuit unit; and the negative electrode of the second reference voltage source is connected with the current input end of the load.
Preferably, the delay circuit unit includes a fourth operational amplifier, a third reference voltage source, a fourth resistor, a fourth capacitor, and a fifth diode; wherein,
a power supply end of the fourth operational amplifier is connected with the first working voltage input end, a ground end of the fourth operational amplifier is connected with a current input end of the load, a non-inverting input end of the fourth operational amplifier is connected with an output end of the third operational amplifier through the fourth resistor, and an inverting input end of the fourth operational amplifier is connected with the anode of the third reference voltage source; the negative electrode of the third reference voltage source is connected with the current input end of the load; the anode of the fifth diode is connected with the non-inverting input end of the fourth operational amplifier, and the cathode of the fifth diode is connected with the output end of the third operational amplifier; the output end of the fourth operational amplifier is the output end of the average current protection circuit, and the output end of the average current protection circuit is connected with the input end of the overcurrent protection execution circuit; the first end of the fourth capacitor is connected with the non-inverting input end of the fourth operational amplifier, and the second end of the fourth capacitor is connected with the current input end of the load.
Preferably, the overcurrent protection execution circuit comprises a second working voltage input end, a fifth resistor, a sixth resistor, a photoelectric coupler and a controlled silicon; wherein,
the anode of a light emitting diode in the photoelectric coupler is respectively connected with the output end of the peak current protection circuit and the output end of the average current protection circuit through the fifth resistor, the cathode of the light emitting diode in the photoelectric coupler is connected with the current input end of the load, the collector of a triode in the photoelectric coupler is connected with the second working voltage input end, and the emitter of the triode in the photoelectric coupler is connected with the control electrode of the controlled silicon through the sixth resistor; the anode of the silicon controlled rectifier is the output end of the overcurrent protection execution circuit, the output end of the overcurrent protection execution circuit is connected with the enabling end of the power input end, and the cathode of the silicon controlled rectifier is grounded.
In addition, in order to achieve the above object, the utility model also provides a television, which comprises an overcurrent protection circuit, the overcurrent protection circuit comprises a power supply input end for providing power supply voltage for a load, a transformer for carrying out voltage conversion on the power supply voltage, a current doubling rectifying circuit for carrying out current doubling rectification on the voltage output by the transformer, a current sampling circuit for sampling the current of the load, a peak current protection circuit for carrying out overcurrent protection on the peak current of the load, an average current protection circuit for carrying out overcurrent protection on the average current of the load, and an overcurrent protection execution circuit for controlling the on-off state of the power supply input end according to an output signal of the peak current protection circuit or an output signal of the average current protection circuit so as to carry out overcurrent protection action on the load; wherein,
the power supply input end is connected with the primary side of the transformer, and the secondary side of the transformer is connected with the load through the current doubling rectifying circuit; the sampling end of the current sampling circuit is connected with the current doubling rectifying circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit; the output end of the peak current protection circuit and the output end of the average current protection circuit are both connected with the input end of the overcurrent protection execution circuit; and the output end of the overcurrent protection execution circuit is connected with the enable end of the power input end.
The utility model provides an overcurrent protection circuit, including be used for the load provide supply voltage's power input end, be used for right supply voltage carries out the transformer of voltage transformation, be used for right the voltage of transformer output carries out the current doubler rectifier circuit of current doubler rectification, be used for right the electric current sampling circuit that the electric current of load took samples, be used for right the peak current of load carries out overcurrent protection's peak current protection circuit, be used for right the average current of load carries out overcurrent protection's average current protection circuit, and be used for according to the output signal of peak current protection circuit or the output signal control of average current protection circuit the power input end open and the closed condition in order to carry out the overcurrent protection executive circuit of overcurrent protection action to the load; the power supply input end is connected with the primary side of the transformer, and the secondary side of the transformer is connected with the load through the current doubling rectifying circuit; the sampling end of the current sampling circuit is connected with the current doubling rectifying circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit; the output end of the peak current protection circuit and the output end of the average current protection circuit are both connected with the input end of the overcurrent protection execution circuit; and the output end of the overcurrent protection execution circuit is connected with the enable end of the power input end. The overcurrent protection circuit can not only carry out overcurrent protection on the peak current of the load, but also carry out overcurrent protection on the average current of the load; and simultaneously, the utility model discloses still have the advantage of circuit structure simple and easy realization.
Drawings
FIG. 1 is a schematic circuit diagram of an embodiment of an over-current protection circuit in the prior art;
fig. 2 is a schematic diagram of a module structure of an embodiment of the overcurrent protection circuit of the present invention;
fig. 3 is a schematic circuit diagram of an embodiment of the overcurrent protection circuit of the present invention.
The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The utility model provides an overcurrent protection circuit.
Referring to fig. 2, fig. 2 is a schematic diagram of a module structure of an embodiment of the overcurrent protection circuit of the present invention.
The overcurrent protection circuit of the present embodiment includes a power input terminal 101, a transformer 102, a current doubler rectifier circuit 103, a current sampling circuit 104, a peak current protection circuit 105, an average current protection circuit 106, and an overcurrent protection execution circuit 107.
In this embodiment, the power input terminal 101 is configured to provide a supply voltage for the load 200;
the transformer 102 is configured to perform voltage conversion on the supply voltage input by the power input terminal 101;
the current-doubling rectifying circuit 103 is used for performing current-doubling rectification on the voltage output by the transformer 102;
the current sampling circuit 104 is configured to sample a current of the load 200;
the peak current protection circuit 105 is configured to perform overcurrent protection on the peak current of the load 200. The peak current protection circuit 105 outputs a first overcurrent protection signal to the input end of the overcurrent protection execution circuit 107;
the average current protection circuit 106 is configured to perform overcurrent protection on the average current of the load 200. The average current protection circuit 106 outputs a second overcurrent protection signal to the input terminal of the overcurrent protection execution circuit 107;
the overcurrent protection execution circuit 107 is configured to control the on and off states of the power input 101 according to an output signal of the peak current protection circuit 105 (i.e., the first overcurrent protection signal) or an output signal of the average current protection circuit 106 (i.e., the second overcurrent protection signal) to perform an overcurrent protection action on the load 200.
Specifically, the power input terminal 101 is connected to the primary side of the transformer 102, and the secondary side of the transformer 102 is connected to the current input terminal of the load 200 through the current doubling rectifying circuit 103; the sampling end of the current sampling circuit 104 is connected with the current doubling rectifying circuit 103, and the output end of the current sampling circuit 104 is respectively connected with the input end of the peak current protection circuit 105 and the input end of the average current protection circuit 106; the output end of the peak current protection circuit 105 and the output end of the average current protection circuit 106 are both connected with the input end of the overcurrent protection execution circuit 107; the output end of the over-current protection execution circuit 107 is connected with the enable end EN of the power input end 101.
Fig. 3 is a schematic circuit diagram of an embodiment of the overcurrent protection circuit of the present invention.
Referring to fig. 2 and 3 together, in the present embodiment, the current doubler rectification circuit 103 includes a first inductor L1, a second inductor L2, a first diode D1, a second diode D2, and an electrolytic capacitor E1;
specifically, a first end of the first inductor L1 is connected to a first end of a secondary winding (not numbered) of the transformer 102, and a second end of the first inductor L1 is connected to a current input end of the load 200 (corresponding to the left end of the load 200 in fig. 3); a first terminal of the second inductor L2 is connected to a second terminal of the secondary winding of the transformer 102, and a second terminal of the second inductor L2 is connected to a second terminal of the first inductor L1; the anode of the electrolytic capacitor E1 is connected to the current input terminal of the load 200, and the cathode of the electrolytic capacitor E1 and the current output terminal of the load 200 (corresponding to the right end of the load 200 in fig. 3) are both grounded (i.e., connected to the secondary side of the transformer 102); the cathode of the first diode D1 is connected with the first end of the first inductor L1, and the anode of the first diode D1 is connected with the anode of the second diode D2 and the cathode of the electrolytic capacitor E1 respectively; the cathode of the second diode D2 is connected to the first end of the second inductor L2.
In this embodiment, the current sampling circuit 104 includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a third diode D3, and a fourth diode D4;
specifically, a first end of the first resistor R1 is connected to a first end of the first inductor L1, and a second end of the first resistor R1 is connected to a first end of the first capacitor C1 and an anode of the third diode D3, respectively; a second terminal of the first capacitor C1 is connected to a second terminal of the first inductor L1; a cathode of the third diode D3 and a cathode of the fourth diode D4 are connected to a first node O, the first node O is an output end of the current sampling circuit 104, and an output end of the current sampling circuit 104 is connected to an input end of the peak current protection circuit 105 and an input end of the average current protection circuit 106, respectively;
a first end of the second resistor R2 is connected to a first end of the second inductor L2, and a second end of the second resistor R2 is connected to a first end of the second capacitor C2 and an anode of the fourth diode D4, respectively; a second terminal of the second capacitor C2 is connected to a second terminal of the second inductor L2; the cathode of the fourth diode D4 is connected to the cathode of the third diode D3.
In this embodiment, the peak current protection circuit 105 includes a first working voltage input end VA, a first operational amplifier OP1 and a first reference voltage source Vref 1;
specifically, a non-inverting input terminal of the first operational amplifier OP1 is connected to an output terminal (i.e., the first node O) of the current sampling circuit 104, an inverting input terminal of the first operational amplifier OP1 is connected to an anode of the first reference voltage source Vref1, an output terminal of the first operational amplifier OP1 is an output terminal of the peak current protection circuit 105, an output terminal of the peak current protection circuit 105 is connected to an input terminal of the over-current protection execution circuit 107, a power supply terminal of the first operational amplifier OP1 is connected to the first working voltage input VA, and a ground terminal of the first operational amplifier OP1 and a cathode of the first reference voltage source Vref1 are both connected to a current input terminal of the load 200.
In this embodiment, the average current protection circuit 106 includes a voltage integrating circuit unit 1061, an average current over-current comparing circuit unit 1062, and a delay circuit unit 1063. The input end of the voltage integrating circuit unit 1061 is connected to the output end of the current sampling circuit 104, and the output end of the voltage integrating circuit unit 1061 is connected to the input end of the average current over-current comparing circuit unit 1062; the output end of the average current over-current comparison circuit unit 1062 is connected with the input end of the delay circuit unit 1063; the output end of the delay circuit unit 1063 is connected to the input end of the over-current protection execution circuit 107.
Specifically, in the present embodiment, the voltage integration circuit unit 1061 includes a second operational amplifier OP2, a third resistor R3, and a third capacitor C3. A power source terminal of the second operational amplifier OP2 is connected to the first working voltage input terminal VA, an inverting input terminal of the second operational amplifier OP2 and a ground terminal of the second operational amplifier OP2 are both connected to the current input terminal of the load 200, a non-inverting input terminal of the second operational amplifier OP2 is connected to an output terminal (i.e., the first node O) of the current sampling circuit 104 through the third resistor R3, and an output terminal of the second operational amplifier OP2 is connected to an input terminal of the average current over-current comparison circuit unit 1062; a first end of the third capacitor C3 is connected to the non-inverting input terminal of the second operational amplifier OP2, and a second end of the third capacitor C3 is connected to the first operating voltage input VA.
In this embodiment, the average current over-current comparing circuit unit 1062 includes a third operational amplifier OP3 and a second reference voltage source Vref 2. A power source terminal of the third operational amplifier OP3 is connected to the first working voltage input VA, a ground terminal of the third operational amplifier OP3 is connected to the current input terminal of the load 200, a non-inverting input terminal of the third operational amplifier OP3 is connected to the output terminal of the second operational amplifier OP2, an inverting input terminal of the third operational amplifier OP3 is connected to the positive electrode of the second reference voltage source Vref2, and an output terminal of the third operational amplifier OP3 is connected to the input terminal of the delay circuit unit 1063; the negative terminal of the second reference voltage source Vref2 is connected to the current input terminal of the load 200.
In this embodiment, the delay circuit unit 1063 includes a fourth operational amplifier OP4, a third reference voltage source Vref3, a fourth resistor R4, a fourth capacitor C4, and a fifth diode D5. A power supply terminal of the fourth operational amplifier OP4 is connected to the first operating voltage input VA, a ground terminal of the fourth operational amplifier OP4 is connected to the current input terminal of the load 200, a non-inverting input terminal of the fourth operational amplifier OP4 is connected to the output terminal of the third operational amplifier OP3 via the fourth resistor R4, and an inverting input terminal of the fourth operational amplifier OP4 is connected to the positive terminal of the third reference voltage source Vref 3; the negative pole of the third reference voltage source Vref3 is connected to the current input terminal of the load 200; an anode of the fifth diode D5 is connected to a non-inverting input terminal of the fourth operational amplifier OP4, and a cathode of the fifth diode D5 is connected to an output terminal of the third operational amplifier OP 3; the output end of the fourth operational amplifier OP4 is the output end of the average current protection circuit 106, and the output end of the average current protection circuit 106 is connected with the input end of the over-current protection execution circuit 107; a first end of the fourth capacitor C4 is connected to the non-inverting input of the fourth operational amplifier OP4, and a second end of the fourth capacitor C4 is connected to the current input of the load 200.
In this embodiment, the over-current protection execution circuit 107 includes a second working voltage input terminal VB, a fifth resistor R5, a sixth resistor R6, a photo-coupler OPC, and a silicon controlled rectifier SCR.
Specifically, the anode of the light emitting diode in the photo-coupler OPC is connected to the output terminal of the peak current protection circuit 105 (i.e., the output terminal of the first operational amplifier OP 1) and the output terminal of the average current protection circuit 106 (i.e., the output terminal of the fourth operational amplifier OP 4) through the fifth resistor R5, respectively, the cathode of the light emitting diode in the photo-coupler OPC is connected to the current input terminal of the load 200, the collector of the triode in the photo-coupler OPC is connected to the second operating voltage input terminal VB, and the emitter of the triode in the photo-coupler OPC is connected to the control terminal of the silicon controlled SCR through the sixth resistor R6; the anode of the thyristor SCR is the output end of the overcurrent protection execution circuit 107, the output end of the overcurrent protection execution circuit 107 is connected to the enable end EN of the power input end 101, and the cathode of the thyristor SCR is grounded (i.e., connected to the primary side of the transformer 102).
In this embodiment, the sampling principle of the current sampling circuit 104 is as follows: the current flowing through the first inductor L1 is the integral of the voltage across the first inductor L1, and the current flowing through the second inductor L2 is the integral of the voltage across the second inductor L2. In this embodiment, the voltage across the first capacitor C1 simulates a value of the current flowing through the first inductor L1, the voltage across the second capacitor C2 simulates a value of the current flowing through the second inductor L2, and a sum of the current flowing through the first inductor L1 and the current flowing through the second inductor L2 is the current flowing through the load 200 (that is, the current information flowing through the load 200 can be obtained by the overcurrent protection circuit without using a sampling resistor in this embodiment). In this embodiment, the third diode D3 and the fourth diode D4 are used for isolating signals.
In this embodiment, the first reference voltage source Vref1 in the peak current protection circuit 105 is used to set the maximum value of the current of the load 200, the first operational amplifier OP1 in the peak current protection circuit 105 compares the current of the load 200 sampled by the current sampling circuit 104 with the maximum value of the current of the load 200 set by the first reference voltage source Vref1, when the current of the load 200 sampled by the current sampling circuit 104 exceeds the maximum value of the current of the load 200 set by the first reference voltage source Vref1, the first operational amplifier OP1 outputs a high-level signal (i.e., the first overcurrent protection signal is at a high level) which lights a light emitting diode in the photocoupler OPC through the fifth resistor R5, the photocoupler OPC operates, and the output of the photocoupler OPC (i.e., the emitter of a transistor in the photocoupler OPC) passes through the output of the photocoupler OPC The sixth resistor R6 triggers the SCR to turn on, so as to lock the enable terminal EN of the power input terminal 101 at a low level, thereby achieving the purpose of turning off the power input terminal 101, and achieving the purpose of overcurrent protection of the peak current of the load 200.
In this embodiment, the voltage integration circuit unit 1061 is configured to integrate the sum of the currents of the load 200 sampled by the current sampling circuit 104 to obtain an average current value of the load 200; in this embodiment, the second reference voltage source Vref2 in the average current overflow comparison circuit unit 1062 is used to set a reference current value of the average current of the load 200, the third operational amplifier OP3 compares the average current value of the load 200 with the reference current value of the average current of the load 200 set by the second reference voltage source Vref2, and the third operational amplifier OP3 outputs a high level signal when the average current value of the load 200 exceeds the reference current value of the average current of the load 200; then, the high level signal outputted from the third operational amplifier OP3 is delayed by the fourth resistor R4, the fourth capacitor C4 and the fifth diode D5, and then compared with the reference voltage of the third reference voltage source Vref3, when the delay time is exceeded, the fourth operational amplifier OP4 outputs a high level signal (i.e. the second over-current protection signal is high level), the high level signal lights a light emitting diode in the photo coupler OPC through the fifth resistor R5, the photoelectric coupler OPC works, the output of the photoelectric coupler OPC (i.e., the emitter of the triode in the photoelectric coupler OPC) triggers the silicon controlled rectifier SCR to be conducted through the sixth resistor R6, so that the enable terminal EN of the power input terminal 101 is locked at a low level, and then the purpose of turning off the power input end 101 is achieved, so that the purpose of overcurrent protection of the average current of the load 200 is achieved. In this embodiment, the purpose of delaying the high-level signal output by the third operational amplifier OP3 is to distinguish short-time overcurrent of the average current of the load 200 and prevent the overcurrent protection circuit of this embodiment from malfunctioning overcurrent protection of the average current of the load 200.
The overcurrent protection circuit provided by this embodiment includes a power input terminal for providing a power supply voltage to a load, a transformer for performing voltage conversion on the power supply voltage, a current doubler rectifier circuit for performing current doubler rectification on a voltage output by the transformer, a current sampling circuit for sampling a current of the load, a peak current protection circuit for performing overcurrent protection on a peak current of the load, an average current protection circuit for performing overcurrent protection on an average current of the load, and an overcurrent protection execution circuit for controlling an on-off state of the power input terminal according to an output signal of the peak current protection circuit or an output signal of the average current protection circuit to perform an overcurrent protection action on the load; the power supply input end is connected with the primary side of the transformer, and the secondary side of the transformer is connected with the load through the current doubling rectifying circuit; the sampling end of the current sampling circuit is connected with the current doubling rectifying circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit; the output end of the peak current protection circuit and the output end of the average current protection circuit are both connected with the input end of the overcurrent protection execution circuit; and the output end of the overcurrent protection execution circuit is connected with the enable end of the power input end. The overcurrent protection circuit can not only carry out overcurrent protection on the peak current of the load, but also carry out overcurrent protection on the average current of the load; meanwhile, the embodiment also has the advantages of simple circuit structure and easy realization.
The utility model also provides a TV set, this TV set include overcurrent protection circuit, and this overcurrent protection circuit's modular structure and circuit structure can refer to above-mentioned embodiment, no longer give consideration to here. It should be understood that, since the television set of the embodiment adopts the technical scheme of the over-current protection circuit, the television set has all the beneficial effects of the over-current protection circuit.
The above is only the preferred embodiment of the present invention, and not the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings or the direct or indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (10)
1. An overcurrent protection circuit, comprising a power input terminal for providing a power supply voltage to a load, a transformer for performing voltage conversion on the power supply voltage, a current doubler rectifier circuit for performing current doubler rectification on a voltage output by the transformer, a current sampling circuit for sampling a current of the load, a peak current protection circuit for performing overcurrent protection on a peak current of the load, an average current protection circuit for performing overcurrent protection on an average current of the load, and an overcurrent protection execution circuit for controlling an on-off state of the power input terminal according to an output signal of the peak current protection circuit or an output signal of the average current protection circuit to perform an overcurrent protection action on the load; wherein,
the power supply input end is connected with the primary side of the transformer, and the secondary side of the transformer is connected with the load through the current doubling rectifying circuit; the sampling end of the current sampling circuit is connected with the current doubling rectifying circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit; the output end of the peak current protection circuit and the output end of the average current protection circuit are both connected with the input end of the overcurrent protection execution circuit; and the output end of the overcurrent protection execution circuit is connected with the enable end of the power input end.
2. The overcurrent protection circuit as set forth in claim 1, wherein said current doubler rectification circuit comprises a first inductor, a second inductor, a first diode, a second diode and an electrolytic capacitor; wherein,
the first end of the first inductor is connected with the first end of the secondary coil of the transformer, and the second end of the first inductor is grounded with the current input end of the load; the first end of the second inductor is connected with the second end of the secondary coil of the transformer, and the second end of the second inductor is connected with the second end of the first inductor; the anode of the electrolytic capacitor is connected with the current input end of the load, and the cathode of the electrolytic capacitor is grounded; the cathode of the first diode is connected with the first end of the first inductor, and the anode of the first diode is respectively connected with the anode of the second diode and the cathode of the electrolytic capacitor; and the cathode of the second diode is connected with the first end of the second inductor.
3. The overcurrent protection circuit of claim 2, wherein the current sampling circuit comprises a first resistor, a second resistor, a first capacitor, a second capacitor, a third diode, and a fourth diode; wherein,
a first end of the first resistor is connected with a first end of the first inductor, and a second end of the first resistor is respectively connected with a first end of the first capacitor and an anode of the third diode; the second end of the first capacitor is connected with the second end of the first inductor; the cathode of the third diode and the cathode of the fourth diode are connected to a first node, the first node is the output end of the current sampling circuit, and the output end of the current sampling circuit is respectively connected with the input end of the peak current protection circuit and the input end of the average current protection circuit;
a first end of the second resistor is connected with a first end of the second inductor, and a second end of the second resistor is respectively connected with a first end of the second capacitor and an anode of the fourth diode; a second end of the second capacitor is connected with a second end of the second inductor; the cathode of the fourth diode is connected to the cathode of the third diode.
4. The overcurrent protection circuit of claim 3, wherein the peak current protection circuit comprises a first operating voltage input, a first operational amplifier, and a first reference voltage source; wherein,
the non-inverting input end of the first operational amplifier is connected with the output end of the current sampling circuit, the inverting input end of the first operational amplifier is connected with the positive electrode of the first reference voltage source, the output end of the first operational amplifier is the output end of the peak current protection circuit, the output end of the peak current protection circuit is connected with the input end of the overcurrent protection execution circuit, the power supply end of the first operational amplifier is connected with the first working voltage input end, and the ground end of the first operational amplifier and the negative electrode of the first reference voltage source are both connected with the current input end of the load.
5. The overcurrent protection circuit according to claim 4, wherein the average current protection circuit comprises a voltage integrating circuit unit, an average current overcurrent comparing circuit unit and a time delay circuit unit; wherein,
the input end of the voltage integrating circuit unit is connected with the output end of the current sampling circuit, and the output end of the voltage integrating circuit unit is connected with the input end of the average current over-current comparison circuit unit; the output end of the average current over-current comparison circuit unit is connected with the input end of the delay circuit unit; and the output end of the delay circuit unit is connected with the input end of the overcurrent protection execution circuit.
6. The overcurrent protection circuit as set forth in claim 5, wherein said voltage integration circuit unit comprises a second operational amplifier, a third resistor and a third capacitor; wherein,
the power supply end of the second operational amplifier is connected with the first working voltage input end, the inverting input end of the second operational amplifier and the ground end of the second operational amplifier are both connected with the current input end of the load, the non-inverting input end of the second operational amplifier is connected with the output end of the current sampling circuit through the third resistor, and the output end of the second operational amplifier is connected with the input end of the average current over-current comparison circuit unit; the first end of the third capacitor is connected with the non-inverting input end of the second operational amplifier, and the second end of the third capacitor is connected with the first working voltage input end.
7. The overcurrent protection circuit according to claim 6, wherein the average current overcurrent comparison circuit unit includes a third operational amplifier and a second reference voltage source; wherein,
the power supply end of the third operational amplifier is connected with the first working voltage input end, the ground end of the third operational amplifier is connected with the current input end of the load, the non-inverting input end of the third operational amplifier is connected with the output end of the second operational amplifier, the inverting input end of the third operational amplifier is connected with the anode of the second reference voltage source, and the output end of the third operational amplifier is connected with the input end of the delay circuit unit; and the negative electrode of the second reference voltage source is connected with the current input end of the load.
8. The overcurrent protection circuit of claim 7, wherein the delay circuit unit comprises a fourth operational amplifier, a third reference voltage source, a fourth resistor, a fourth capacitor, and a fifth diode; wherein,
a power supply end of the fourth operational amplifier is connected with the first working voltage input end, a ground end of the fourth operational amplifier is connected with a current input end of the load, a non-inverting input end of the fourth operational amplifier is connected with an output end of the third operational amplifier through the fourth resistor, and an inverting input end of the fourth operational amplifier is connected with the anode of the third reference voltage source; the negative electrode of the third reference voltage source is connected with the current input end of the load; the anode of the fifth diode is connected with the non-inverting input end of the fourth operational amplifier, and the cathode of the fifth diode is connected with the output end of the third operational amplifier; the output end of the fourth operational amplifier is the output end of the average current protection circuit, and the output end of the average current protection circuit is connected with the input end of the overcurrent protection execution circuit; the first end of the fourth capacitor is connected with the non-inverting input end of the fourth operational amplifier, and the second end of the fourth capacitor is connected with the current input end of the load.
9. The overcurrent protection circuit according to claim 8, wherein the overcurrent protection execution circuit comprises a second operating voltage input terminal, a fifth resistor, a sixth resistor, a photocoupler and a thyristor; wherein,
the anode of a light emitting diode in the photoelectric coupler is respectively connected with the output end of the peak current protection circuit and the output end of the average current protection circuit through the fifth resistor, the cathode of the light emitting diode in the photoelectric coupler is connected with the current input end of the load, the collector of a triode in the photoelectric coupler is connected with the second working voltage input end, and the emitter of the triode in the photoelectric coupler is connected with the control electrode of the controlled silicon through the sixth resistor; the anode of the silicon controlled rectifier is the output end of the overcurrent protection execution circuit, the output end of the overcurrent protection execution circuit is connected with the enabling end of the power input end, and the cathode of the silicon controlled rectifier is grounded.
10. A television set, characterized in that it comprises an overcurrent protection circuit as claimed in any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520265627.XU CN204559093U (en) | 2015-04-28 | 2015-04-28 | Current foldback circuit and television set |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520265627.XU CN204559093U (en) | 2015-04-28 | 2015-04-28 | Current foldback circuit and television set |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204559093U true CN204559093U (en) | 2015-08-12 |
Family
ID=53834164
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520265627.XU Expired - Fee Related CN204559093U (en) | 2015-04-28 | 2015-04-28 | Current foldback circuit and television set |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204559093U (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106451341A (en) * | 2016-11-22 | 2017-02-22 | 亿嘉和科技股份有限公司 | Load overcurrent protection circuit and load overcurrent protection method |
| CN106454172A (en) * | 2016-12-22 | 2017-02-22 | 深圳Tcl数字技术有限公司 | Power supply circuit and TV set |
| CN111934281A (en) * | 2020-08-10 | 2020-11-13 | 迈普通信技术股份有限公司 | Electronic equipment overtemperature protection circuit, electronic equipment and overtemperature protection control method |
| CN118174421A (en) * | 2024-05-13 | 2024-06-11 | 深圳麦格米特电气股份有限公司 | Current-limiting protection circuit and electronic equipment |
| CN118199584A (en) * | 2024-04-19 | 2024-06-14 | 北京宁海芯科集成电路设计有限公司 | Switch protection circuit and electronic equipment |
-
2015
- 2015-04-28 CN CN201520265627.XU patent/CN204559093U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106451341A (en) * | 2016-11-22 | 2017-02-22 | 亿嘉和科技股份有限公司 | Load overcurrent protection circuit and load overcurrent protection method |
| CN106454172A (en) * | 2016-12-22 | 2017-02-22 | 深圳Tcl数字技术有限公司 | Power supply circuit and TV set |
| CN106454172B (en) * | 2016-12-22 | 2019-11-05 | 深圳Tcl数字技术有限公司 | Power circuit and television set |
| CN111934281A (en) * | 2020-08-10 | 2020-11-13 | 迈普通信技术股份有限公司 | Electronic equipment overtemperature protection circuit, electronic equipment and overtemperature protection control method |
| CN118199584A (en) * | 2024-04-19 | 2024-06-14 | 北京宁海芯科集成电路设计有限公司 | Switch protection circuit and electronic equipment |
| CN118174421A (en) * | 2024-05-13 | 2024-06-11 | 深圳麦格米特电气股份有限公司 | Current-limiting protection circuit and electronic equipment |
| CN118174421B (en) * | 2024-05-13 | 2024-08-20 | 深圳麦格米特电气股份有限公司 | Current-limiting protection circuit and electronic equipment |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN204559093U (en) | Current foldback circuit and television set | |
| CN203368317U (en) | High PFC constant current control device without loop compensation and voltage converter | |
| KR101945909B1 (en) | Led backlight drive circuit and liquid crystal display | |
| CN106535390A (en) | Constant current driving power supply and display equipment | |
| CN107809830B (en) | Buck-boost LED drive circuit | |
| US9654020B2 (en) | Smart matching step-down circuits and travel-use power conversion devices | |
| CN105322803A (en) | Constant-voltage and constant-current synchronous output power supply and television | |
| EP3595413B1 (en) | Constant current led power supply circuit with maximum output power limiting circuit | |
| CN103763830A (en) | Light-emitting element driving system and drive and control circuit and driving method | |
| CN104185333A (en) | Constant-current constant-voltage circuit and illuminating device | |
| CN101621877A (en) | Current feed circuit and current control circuit of light emitting diode | |
| CN115802546B (en) | Dual-mode output dimming power supply | |
| CN103683204A (en) | Switching power supply over-current protection circuit | |
| JP2015053225A (en) | Led drive circuit | |
| CN109195249B (en) | Dial switch circuit based on silicon controlled rectifier | |
| CN204538956U (en) | Reduce the circuit of total harmonic distortion and raising power factor | |
| CN205753994U (en) | Multiple-output electric power and electronic equipment | |
| CN203675399U (en) | Light-emitting element driving system and driving control circuit | |
| CN111585448A (en) | Constant current output control circuit, switching power supply controller and switching power supply system | |
| US11653430B2 (en) | Lamp control system | |
| CN212163794U (en) | High-power linear dimming power supply | |
| CN211579881U (en) | Simple negative-voltage and boosting auxiliary power circuit and switching power supply | |
| CN212435587U (en) | Constant current output control circuit, switching power supply controller and switching power supply system | |
| CN211019358U (en) | Voltage reduction driving circuit | |
| CN106385755B (en) | Constant voltage and current limiting control circuit applied to gas discharge lamp ballast |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150812 |