CN204335061U - LED dimming driving circuit and output current control circuit thereof and bypass composite device - Google Patents
LED dimming driving circuit and output current control circuit thereof and bypass composite device Download PDFInfo
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- CN204335061U CN204335061U CN201420794746.XU CN201420794746U CN204335061U CN 204335061 U CN204335061 U CN 204335061U CN 201420794746 U CN201420794746 U CN 201420794746U CN 204335061 U CN204335061 U CN 204335061U
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Abstract
The utility model provides a kind of LED dimming driving circuit and output current control circuit thereof and bypass composite device, and this device comprises: field effect transistor, and its drain electrode connects high voltage input terminal; Bypass common circuit, according to the supply voltage of dim signal and power end, control the operating state of field effect transistor, regulate the bypass impedance between the source electrode of field effect transistor and ground according to by-passing signal, control the charged state to power end in startup and/or the course of work according to dim signal and supply voltage.Traditional bypass circuit and startup and power supply circuits are integrated in same composite device by the utility model, are conducive to peripheral circuits, reduce complete machine cost.
Description
Technical field
The utility model relates to LED dimming driving circuit, particularly relates to a kind of bypass composite device for control unit and comprises the output current control circuit of this device, comprise the LED dimming driving circuit of this output current control circuit.
Background technology
With reference to figure 1, the LED drive circuit of traditional band dimmer of being powered by alternating current input power supplying mainly comprises: dimmer 101, rectification circuit 102, input filter capacitor C1, bypass circuit 103, diode D2, output current control circuit 105, power transfer circuitry 106 and LED string.Output current control circuit 105 comprises startup and power supply circuits 1051, power control circuit 1052, dim signal produce circuit 1053 and by-passing signal produces circuit 1054.Bypass circuit 103 comprises resistance R1, electric capacity C2, metal-oxide-semiconductor M1, voltage-stabiliser tube D1 and bypass impedance control circuit 104 further.
Wherein, dim signal produces the dimming state generation dim signal that circuit 1053 provides according to dimmer 101, and by-passing signal produces circuit 1054 for generation of by-passing signal, and this by-passing signal is used for controlling bypass circuit 103.Bypass circuit 103 provides a circuit pathways, to ensure the normal work of dimmer 101 for dimmer 101.General input ac voltage controls the impedance of bypass circuit 103, when AC-input voltage is near zero passage, bypass circuit 103 is in conducting state, now, dimmer 101, rectification circuit 102 and bypass circuit 103 form current circuit, and dimmer 101 has the electric current of setting to flow through, power to dimmer 101, just do not need extra dimmer powered loop thus.Startup in output current control circuit 105 and power supply circuits 1051 are used for starting output current control circuit 105 fast, and the general depletion type MOS tube M2 of N-type that uses provides quick startup, realizes high voltage startup function.In the standby state, depletion type MOS tube M2 is also used for maintaining the power supply of electric capacity C3, to ensure normal power supply and the work of output current control circuit 105, realizes high voltage supply function.
But there is the problem that element is more, circuit structure is complicated in the traditional circuit described in Fig. 1.
Utility model content
Problem to be solved in the utility model is to provide a kind of LED dimming driving circuit and output current control circuit thereof and bypass composite device, traditional bypass circuit and startup and/or power supply circuits are integrated in same composite device, be conducive to peripheral circuits, reduce complete machine cost.
For solving the problems of the technologies described above, the utility model provides a kind of bypass composite device, comprising:
Field effect transistor, its drain electrode connects high voltage input terminal;
Bypass common circuit, receive dim signal and by-passing signal, connect grid and the source electrode of power end and described field effect transistor, the operating state of described field effect transistor is controlled according to the supply voltage of described dim signal and described power end, regulate the bypass impedance between the source electrode of described field effect transistor and ground according to described by-passing signal, control the charged state to described power end in startup and/or the course of work according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described high voltage input terminal forms the bypass path between ground via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
According to an embodiment of the present utility model, high voltage input terminal forms the charging path between described power end via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in startup and the course of work according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in the course of work according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in start-up course according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal.
According to an embodiment of the present utility model, described bypass control circuit comprises one or more impedance path, and described impedance path comprises:
Switch, its first end connects the source electrode of described field effect transistor;
Impedance, its first end connects the second end of described switch, its second end ground connection;
Wherein, the turn-on and turn-off of described switch are controlled by described by-passing signal.
According to an embodiment of the present utility model, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
First switching tube, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its second end connects described power end, and its control end connects the drain electrode of described metal-oxide-semiconductor;
First resistance, its first end connects the first end of described first switching tube, and its second end connects the control end of described first switching tube.
According to an embodiment of the present utility model, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
Second switch pipe, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its control end connects the drain electrode of described metal-oxide-semiconductor;
3rd switching tube, its first end connects the control end of described second switch pipe, and its control end connects the second end of described second switch pipe;
Second resistance, its first end connects the first end of described second switch pipe, and its second end connects the control end of described second switch pipe;
3rd resistance, its first end connects the control end of described 3rd switching tube, and its second end connects the second end of described 3rd switching tube;
Anti-discharge diode, its anode connects the second end of described 3rd switching tube, and its negative electrode connects described power end.
According to an embodiment of the present utility model, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal;
Wherein, described gate voltage control circuit comprises:
First switch, its first end connects the grid of described field effect transistor, and its second end is via the 4th grounding through resistance;
Second switch, its first end connects the grid of described field effect transistor, and its second termination receives grid bootstrap voltage mode, and described grid bootstrap voltage mode equals the source voltage of described field effect transistor and the reference voltage sum preset;
3rd switch, its first end connects the grid of described field effect transistor, and its second end is connected to the source electrode of described field effect transistor via the 5th resistance;
Wherein, the turn-on and turn-off of described first switch, second switch and the 3rd switch are controlled by described supply voltage and dim signal.
According to an embodiment of the present utility model, described gate voltage control circuit also comprises grid boostrap circuit, and for generation of described grid bootstrap voltage mode, described grid boostrap circuit comprises:
4th switch, its first end connects the grid of described field effect transistor;
5th switch, its first end receives described reference voltage;
Electric capacity, its first end connects the second end of described 4th switch and the second end of the 5th switch;
6th switch, its first end connects the second end of described electric capacity, its second end ground connection;
7th switch, its first end connects the second end of described electric capacity, and its second end connects the source electrode of described field effect transistor.
According to an embodiment of the present utility model, described power end is configured to be connected with the first end of electric capacity of powering, the second end ground connection of described power supply electric capacity.
According to an embodiment of the present utility model, described field effect transistor is depletion field effect transistor.
According to an embodiment of the present utility model, described field effect transistor is enhancement mode field effect transistor or depletion field effect transistor.
According to an embodiment of the present utility model, described field effect transistor is depletion field effect transistor.
In order to solve the problem, the utility model additionally provides a kind of output current control circuit, comprising:
Bypass composite device, described bypass composite device comprises:
Field effect transistor, its drain electrode connects high voltage input terminal;
Bypass common circuit, receive dim signal and by-passing signal, connect grid and the source electrode of power end and described field effect transistor, the operating state of described field effect transistor is controlled according to the supply voltage of described dim signal and described power end, regulate the bypass impedance between the source electrode of described field effect transistor and ground according to described by-passing signal, control the charged state to described power end in startup and/or the course of work according to described dim signal and described supply voltage;
Dim signal produces circuit, for the dimming state of detection control unit to produce described dim signal;
Power control circuit, produces the control signal being used for regulating load electric current or bearing power according to described dim signal.
According to an embodiment of the present utility model, described high voltage input terminal forms the bypass path between ground via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
According to an embodiment of the present utility model, described high voltage input terminal forms the charging path between described power end via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in startup and the course of work according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in the course of work according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit controls the charged state of power end described in start-up course according to described dim signal and described supply voltage.
According to an embodiment of the present utility model, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal.
According to an embodiment of the present utility model, described bypass control circuit comprises one or more impedance path, and described impedance path comprises:
Switch, its first end connects the source electrode of described field effect transistor;
Impedance, its first end connects the second end of described switch, its second end ground connection;
Wherein, the turn-on and turn-off of described switch are controlled by described by-passing signal.
According to an embodiment of the present utility model, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
First switching tube, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its second end connects described power end, and its control end connects the drain electrode of described metal-oxide-semiconductor;
First resistance, its first end connects the first end of described first switching tube, and its second end connects the control end of described first switching tube.
According to an embodiment of the present utility model, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
Second switch pipe, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its control end connects the drain electrode of described metal-oxide-semiconductor;
3rd switching tube, its first end connects the control end of described second switch pipe, and its control end connects the second end of described second switch pipe;
Second resistance, its first end connects the first end of described second switch pipe, and its second end connects the control end of described second switch pipe;
3rd resistance, its first end connects the control end of described 3rd switching tube, and its second end connects the second end of described 3rd switching tube;
Anti-discharge diode, its anode connects the second end of described 3rd switching tube, and its negative electrode connects described power end.
According to an embodiment of the present utility model, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal;
Wherein, described gate voltage control circuit comprises:
First switch, its first end connects the grid of described field effect transistor, and its second end is via the 4th grounding through resistance;
Second switch, its first end connects the grid of described field effect transistor, and its second termination receives grid bootstrap voltage mode, and described grid bootstrap voltage mode equals the source voltage of described field effect transistor and the reference voltage sum preset;
3rd switch, its first end connects the grid of described field effect transistor, and its second end is connected to the source electrode of described field effect transistor via the 5th resistance;
Wherein, the turn-on and turn-off of described first switch, second switch and the 3rd switch are controlled by described supply voltage and dim signal.
According to an embodiment of the present utility model, described gate voltage control circuit also comprises grid boostrap circuit, and for generation of described grid bootstrap voltage mode, described grid boostrap circuit comprises:
4th switch, its first end connects the grid of described field effect transistor;
5th switch, its first end receives described reference voltage;
Electric capacity, its first end connects the second end of described 4th switch and the second end of the 5th switch;
6th switch, its first end connects the second end of described electric capacity, its second end ground connection;
7th switch, its first end connects the second end of described electric capacity, and its second end connects the source electrode of described field effect transistor.
According to an embodiment of the present utility model, described power end is configured to be connected with the first end of electric capacity of powering, the second end ground connection of described power supply electric capacity.
According to an embodiment of the present utility model, described output current control circuit also comprises: by-passing signal produces circuit, in response to the Preset Time after the Preset Time before ac input signal zero passage to zero passage, described by-passing signal produces circuit and produces described by-passing signal.
According to an embodiment of the present utility model, described field effect transistor is depletion field effect transistor.
According to an embodiment of the present utility model, described field effect transistor is enhancement mode field effect transistor or depletion field effect transistor.
According to an embodiment of the present utility model, described field effect transistor is depletion field effect transistor.
In order to solve the problem, the utility model additionally provides a kind of LED dimming driving circuit, comprises the output current control circuit described in above-mentioned any one.
According to an embodiment of the present utility model, described LED dimming driving circuit also comprises:
Alternating current input power supplying, it has interchange input first end and exchanges input second end, and described interchange inputs the second end ground connection;
Control unit, its input connects interchange input first end;
Rectification circuit, its input first end connects the output of described control unit, and it inputs the second end and connects interchange input second end, and it exports first end and connects described high voltage input terminal;
Input filter capacitor, its first end connects the output first end of described rectification circuit, and its second end connects output second end of described rectification circuit and ground connection;
Diode, its anode connects the output plus terminal of described rectification circuit;
Power transfer circuitry, its first input end connects the negative electrode of described diode, and its second input connects the output of described power control circuit, and its output is for connecting load.
According to an embodiment of the present utility model, described alternating current input power supplying, control unit, field effect transistor and bypass common circuit form a galvanic circle under the state of described field effect transistor conducting, and this galvanic circle is used for powering to described control unit; Disconnect under the state that described galvanic circle turns off in described field effect transistor.
According to an embodiment of the present utility model, described control unit is dimmer.
Compared with prior art, the utility model has the following advantages:
Bypass circuit in traditional circuit and startup and/or power supply circuits integrate by the bypass composite device of the utility model embodiment, share same field effect transistor and charging path to power end in bypass path and startup and/or the course of work is provided, be conducive to peripheral circuits, circuit is simple and be easy to realize, be conducive to reducing complete machine cost, reduce the area of PCB, be also conducive to the miniaturization of product.
Accompanying drawing explanation
Fig. 1 is the electrical block diagram of a kind of LED dimming driving circuit in prior art;
Fig. 2 is the electrical block diagram of the LED dimming driving circuit according to the utility model first embodiment;
Fig. 3 is the electrical block diagram of the bypass composite device according to the utility model first embodiment;
Fig. 4 A produces time diagram according to the by-passing signal of the bypass composite device of the utility model first embodiment;
Fig. 4 B is the electrical block diagram according to the bypass control circuit in the bypass composite device of the utility model first embodiment;
Fig. 5 A is a kind of electrical block diagram according to the power charging circuit in the bypass composite device of the utility model first embodiment;
Fig. 5 B is the another kind of electrical block diagram according to the power charging circuit in the bypass composite device of the utility model first embodiment;
Fig. 6 is the electrical block diagram according to the gate voltage control circuit in the bypass composite device of the utility model first embodiment;
Fig. 7 A is the electrical block diagram according to the grid boostrap circuit in the bypass composite device of the utility model first embodiment;
Fig. 7 B is the equivalent circuit structure schematic diagram in a first state of grid boostrap circuit shown in Fig. 7 A;
Fig. 7 C is the equivalent circuit structure schematic diagram in the second condition of grid boostrap circuit shown in Fig. 7 A;
Fig. 8 is the electrical block diagram of the LED dimming driving circuit according to the utility model second embodiment;
Fig. 9 is the electrical block diagram of the LED dimming driving circuit according to the utility model the 3rd embodiment.
Embodiment
Below in conjunction with specific embodiments and the drawings, the utility model is described in further detail, but should not limit protection range of the present utility model with this.
First embodiment
With reference to figure 2, the LED dimming driving circuit of the first embodiment mainly comprises: control unit 101, rectification circuit 102, input filter capacitor C1, diode D2, power supply electric capacity C3, output current control circuit 105 and power transfer circuitry 106.Wherein, power transfer circuitry 106 is connected with LED string 107, to power to LED string 107.Control unit 101 can be dimmer, control panel etc., is described in the present embodiment for dimmer.
Furthermore, the input of dimmer 101 connects interchange input anode; The input anode of rectification circuit 102 connects the output of dimmer 101, and the input negative terminal of rectification circuit 102 connects interchange input negative terminal, and the output plus terminal of rectification circuit 102 connects high voltage input terminal; The first end of input filter capacitor C1 connects the output plus terminal of rectification circuit 102, and second end of input filter capacitor C1 connects the output negative terminal of rectification circuit 102 and ground connection; The anode of diode D2 connects the output plus terminal of rectification circuit 102; Output current control circuit 105 has high voltage input terminal, power end Vcc and output, and this high voltage input terminal connects the output plus terminal of rectification circuit 102, and this power end Vcc connects the first end of power supply electric capacity C3, the second end ground connection of power supply electric capacity C3; The first input end of power transfer circuitry 106 connects the negative electrode of diode D2, and its second input connects the output of output current control circuit 105, and its output connects load 107, and this load 107 can be LED string.
Supply voltage on output capacitance C3 is used for powering to output current control circuit 105.
Output current control circuit 105 can comprise bypass composite device, power control circuit 1052, dim signal produces circuit 1053 and by-passing signal produces circuit 1054.Wherein, bypass composite device can comprise depletion field effect transistor M2 and bypass common circuit 1051.
The drain electrode of depletion field effect transistor M2 connects high voltage input terminal, and be also the output plus terminal of rectification circuit 102, the grid of depletion field effect transistor M2 is connected bypass common circuit 1051 with source electrode.
Bypass common circuit 1051 is integrated with startup, power supply and bypass functionality.Specifically, bypass common circuit 1051 receives dim signal and by-passing signal, connect grid and the source electrode of power end Vcc and depletion field effect transistor M2, according to the supply voltage of dim signal and power end Vcc, control the operating state of depletion field effect transistor M2, regulate the bypass impedance between the source electrode of depletion field effect transistor M2 and ground according to by-passing signal, control the charged state (charged state of the electric capacity C3 that also namely powers) of power end Vcc in startup and the course of work according to dim signal and supply voltage.Bypass impedance between the source electrode of depletion field effect transistor M2 and ground refers to the impedance of the bypass path (or being called current path) between the source electrode of depletion field effect transistor M2 and ground.
Wherein, during depletion field effect transistor M2 conducting, the output plus terminal of rectification circuit 102 is formed into the bypass path on ground via depletion field effect transistor M2 and bypass common circuit 1051, and the output plus terminal of rectification circuit 102 forms the charging path to power end charging via depletion field effect transistor M2 and bypass common circuit 1051.
Herein, " startup " refer to opening process when bypass composite device, output current control circuit 105 and whole LED dimming driving circuit power on; " work " refers to the state providing normal function after bypass composite device, output current control circuit 105 and whole LED dimming driving circuit start.In startup and the course of work, each circuit module all needs power supply, and also namely bypass common circuit 1051 couples of power end Vcc charge, and makes accumulation on power end Vcc have enough electric charges to provide energy to circuit.
Dimmer 101 is for providing dimming state, and dim signal produces circuit 1053 for detecting this dimming state, to produce dim signal.Dim signal produces circuit 1053 and can be powered by power end Vcc.
Power control circuit 1052 can be powered by power end Vcc, regulates electric current or the power of LED string 107 according to this dim signal.Power control circuit 1052 can be constant current control circuit usually, but also can be firm power control circuit.
Power transfer circuitry 106 can be various transformer configuration, it can be such as step-down (BUCK) topological structure, buck (BUCK-BOOST) topological structure, flyback (FLYBACK) topological structure, normal shock (Forward) topological structure, half-bridge (Half-bridge) topological structure, full-bridge (Full-bridge) topological structure, recommends (any one in Push-pull topological structure.
Bypass common circuit 1051 and power transfer circuitry 106 are kept apart, to prevent influencing each other between bypass common circuit 1051 and power transfer circuitry 106 by diode D2.
Show the detailed construction of the bypass composite device in the present embodiment with reference to figure 3, Fig. 3, wherein, bypass common circuit 1051 can comprise: power supply (Vcc) charging circuit 201, bypass control circuit 202 and gate voltage control circuit 203.
Wherein, gate voltage control circuit 203 produces grid voltage Vg and charging control signal according to the supply voltage of power end Vcc and dim signal, and grid voltage Vg transfers to the grid of depletion field effect transistor M2 to control the turn-on and turn-off of depletion field effect transistor M2; The first end of Vcc charging circuit 201 connects the source electrode of depletion field effect transistor M2, its second end is connected to power supply electric capacity C3 via power end Vcc, its control end receives charging control signal, the charging path between the source electrode of Vcc charging circuit 201 conducting or switching off depletion type field effect transistor M2 under the control of charging control signal and power end Vcc; Bypass control circuit 202 for providing the bypass path between the source electrode of depletion field effect transistor M2 and ground, and regulates the bypass impedance of this bypass path according to by-passing signal.This bypass path is that dimmer provides current path, ensure that the normal work of dimmer.
Further, VCC charging circuit 201 and gate voltage control circuit 203 cooperatively interact, in order to realize the control of the charging process to power supply electric capacity C3, before circuit start, give power supply electric capacity C3 charging fast, in the standby state, power supply electric capacity C3 to power to make the supply voltage at its two ends to remain on suitable scope.
More specifically, in circuit start process, the grid voltage Vg that gate voltage control circuit 203 controls depletion field effect transistor M2 is substantially identical with source voltage Vs, makes depletion field effect transistor M2 conducting, VCC charging circuit 201 conducting, to power supply electric capacity C3 charging.When the supply voltage on the electric capacity C3 that powers reaches the first set point, VCC charging circuit 201 disconnects, and stops charging to power supply electric capacity C3 from high voltage input terminal through depletion field effect transistor M2.In order to switching off depletion type field effect transistor M2 preferably, the grid voltage Vg of depletion field effect transistor M2 can be set to comparatively electronegative potential, so that switching off depletion type field effect transistor M2 effectively.In the course of the work under (such as holding state), due to the power consumption of output current control circuit 105 inner member, supply voltage on power supply electric capacity can reduce gradually, when the supply voltage on the electric capacity C3 that powers drops to the second set point, in conjunction with the operating state (also namely in conjunction with dim signal) of dimmer, gate voltage control circuit 203 regulates the grid voltage Vg of depletion field effect transistor M2, to make depletion field effect transistor M2 conducting, control VCC charging circuit 201 conducting simultaneously, to charge to power supply electric capacity C3.When the supply voltage on the electric capacity C3 that powers is elevated to the 3rd set point, VCC charging circuit 201 disconnects, and stops power supply electric capacity C3 charging.
As a preferred embodiment, the 3rd set point is greater than the second set point and is less than the first set point, to make supply voltage when starting slightly larger than supply voltage during normal work, ensures that circuit starts fast.
Bypass control circuit 202 receives dim signal, according to the dim signal of input, regulates the bypass impedance between the source electrode of depletion field effect transistor M2 and ground.Such as, bypass control circuit 202 can select given bypass impedance according to dim signal, provides the by-pass current of setting to dimmer.
Gate voltage control circuit 203 controls the grid voltage Vg of depletion field effect transistor M2, so that control effective shutoff and the conducting of depletion field effect transistor M2.
Show the generation sequential of by-passing signal with reference to figure 4A and Fig. 4 B, Fig. 4 A, Fig. 4 B shows a kind of structure of the bypass control circuit 202 in Fig. 3.This bypass control circuit 202 comprises switch S 1 and switch S 2, and switch S 1 and switch S 2 are connected with impedance 1 and impedance 2 respectively, forms two impedance path, and one end of two impedance path is connected with depletion field effect transistor M2 source electrode, other end ground connection.The turn-on and turn-off of switch S 1 and switch S 2 are controlled by by-passing signal K1 and K2.Near ac input signal VAC zero passage (such as, the Preset Time after the Preset Time before zero passage to zero passage), by-passing signal produces circuit and produces by-passing signal K1, K2, controls the switch S 1 in bypass control circuit 202 and switch S 2.When bypass control circuit 202 conducting, for dimmer provides bypass path, realize the power supply of dimmer.
Furthermore, when switch S 1 conducting, switch S 2 turn off, only impedance 1 accesses the path between depletion field effect transistor M2 source electrode and ground; When switch S 1 turn off, switch S 2 conducting time, only impedance 2 accesses the path between depletion field effect transistor M2 source electrode and ground; When switch S 1 conducting, switch S 2 also conducting, the path between the parallel connection access depletion field effect transistor M2 source electrode of impedance 1 and impedance 2 and ground; When switch S 1 turn off, switch S 2 turn off time, impedance 1 and impedance 2 all disconnect, and the path also namely between depletion field effect transistor M2 source electrode and ground disconnects.Thus, the multiple impedance between depletion field effect transistor M2 source electrode and ground is achieved.
In addition, when the bypass condition needed is more, the impedance path of other quantity can be used to realize.Such as, can use 1,3,4 impedance path in parallel, the impedance in each impedance path can be identical, also can be different.
Show a kind of circuit structure of the VCC charging circuit 201 in Fig. 3 with reference to figure 5A, Fig. 5 A, mainly comprise: the anti-diode D3 that plays a reversed role, its anode connects the source electrode Vs of depletion field effect transistor; Metal-oxide-semiconductor M3, its grid receives charging control signal, its source ground; Switching tube npn1, its first end connects the negative electrode of the anti-diode D3 that plays a reversed role, and its second end connects power end Vcc, and its control end connects the drain electrode of metal-oxide-semiconductor M3; Resistance R3, the first end of its first end connecting valve pipe npn1, the control end of its second end connecting valve pipe npn1.
In example shown in Fig. 5 A, metal-oxide-semiconductor M3 can be NMOS tube, and switching tube npn1 can be NPN type triode.Wherein, the collector electrode of NPN type triode is as first end, and emitter is as the second end, and base stage is as control end.Certainly, switching tube npn1 also can adopt nmos pass transistor.
The source electrode Vs of switching tube npn1 for preventing the grid of current from power source end Vcc and metal-oxide-semiconductor M3 from moving back to depletion field effect transistor.For metal-oxide-semiconductor M3 for NMOS tube, when charging control signal is logic high, then NMOS tube M3 conducting, switching tube npn1 turns off; When charging control signal is logic low, then NMOS tube M3 turns off, and switching tube npn1 conducting, charges normal, and the size of charging current is determined by the multiplication factor of resistance R3 and switching tube npn1.In order to improve charging current, switching tube npn1 can use Darlington transistor to realize.
Show the another kind of circuit structure of the VCC charging circuit 201 in Fig. 3 with reference to figure 5B, Fig. 5 B, mainly comprise: the anti-diode D3 that plays a reversed role, its anode connects the source electrode Vs of depletion field effect transistor; Metal-oxide-semiconductor M3, its grid receives charging control signal, its source ground; Switching tube npn2, its first end connects the negative electrode of the anti-diode D3 that plays a reversed role, and its control end connects the drain electrode of metal-oxide-semiconductor M3; Switching tube npn3, the control end of its first end connecting valve pipe npn2, second end of its control end connecting valve pipe npn2; Resistance R3, the first end of its first end connecting valve pipe npn2, the control end of its second end connecting valve pipe npn2; Resistance R4, the control end of its first end connecting valve pipe npn3, second end of its second end connecting valve pipe npn3; Anti-discharge diode D4, second end of its anode connecting valve pipe npn3, its negative electrode connects power end Vcc.
Similarly, metal-oxide-semiconductor M3 can be NMOS tube, and switching tube npn2 and switching tube npn3 can be NPN type triode.Wherein, the collector electrode of NPN type triode is as first end, and emitter is as the second end, and base stage is as control end.Certainly, switching tube npn2 and switching tube npn3 also can adopt nmos pass transistor.
In VCC charging circuit shown in Fig. 5 B, size of current uses npn3 and resistance R4 to control.When charging current increases, the voltage on resistance R4 raises, and makes switching tube npn3 conducting, limits the further increase of electric current on resistance R4.When metal-oxide-semiconductor M3 pipe conducting, the base stage of switching tube npn2 is drop-down, base-collector junction (bc knot) the meeting conducting of switching tube npn3, electric current drains on metal-oxide-semiconductor M3 by from power end Vcc through the base-collector junction (bc knot) of resistance R4, switching tube npn3, can cause the invalid electric discharge of power supply electric capacity C3 (with reference to figure 3), and anti-discharge diode D4 effectively can prevent the generation of this situation.
Show a kind of circuit structure of the gate voltage control circuit 203 in Fig. 3 with reference to figure 6, Fig. 6, mainly comprise: switch S 3, its first end connects the grid of depletion field effect transistor, and its second end is via resistance R5 ground connection; Switch S 4, its first end connects the grid of depletion field effect transistor, and its second termination receives grid bootstrap voltage mode, and this grid bootstrap voltage mode equals the source voltage Vs of depletion field effect transistor and the reference voltage Vref sum preset; Switch S 5, its first end connects the grid of depletion field effect transistor, and its second end is connected to the source electrode of depletion field effect transistor via resistance R6; Wherein, the turn-on and turn-off of switch S 3, switch S 4 and switch S 5 are controlled directly or indirectly by supply voltage and dim signal.Be in different turn-on and turn-off states by switch S 3, switch S 4 and switch S 5, make grid voltage Vg can equal corresponding voltage.
Furthermore, during switch S 3 conducting, the grid voltage Vg of depletion field effect transistor M2, via resistance R5 ground connection, makes depletion field effect transistor M2 turn off.Wherein, resistance R5 can be set to 0.
Composition graphs 3 and Fig. 6, before output current control circuit 105 starts, switch S 5 conducting, the grid of depletion field effect transistor M2 is connected to the source electrode of depletion field effect transistor M2 through resistance R6, make depletion field effect transistor M2 conducting, now, the conductive capability of the depletion field effect transistor M2 of conducting is relatively weak.
After output current control circuit 105 starts, gate voltage control circuit 203 receives dim signal, when this dim signal requires to connect bypass path, in order to reduce the conducting resistance of depletion field effect transistor M2, switch S 4 conducting, the grid of depletion field effect transistor M2 receives grid bootstrap voltage mode, is also, the grid voltage Vg of depletion field effect transistor M2 equals source voltage Vs and adds default reference voltage Vref, to improve the conductive capability of depletion field effect transistor M2.
Magnitude of voltage due to grid bootstrap voltage mode Vs+Vref has exceeded the supply voltage of output current control circuit 105, therefore, needs grid boostrap circuit to realize the lifting of voltage.
Show a kind of grid boostrap circuit with reference to figure 7A ~ Fig. 7 C, Fig. 7 A, Fig. 7 B and Fig. 7 C respectively illustrates the equivalent electric circuit of Fig. 7 A under different conditions.This grid boostrap circuit comprises: switch S 6, and its first end connects the grid of depletion field effect transistor with receiving grid pole tension Vg; Switch S 7, its first end receives reference voltage Vref; Electric capacity C4, second end of its first end connecting valve S6 and the second end of switch S 7; Switch S 8, its first end connects second end of electric capacity C4, its second end ground connection; Switch S 9, its first end connects second end of electric capacity C4, and its second end connects the source electrode of depletion field effect transistor to receive source voltage Vs.
Bootstrap process mainly comprises two states: the first state, switch S 7 and switch S 8 conducting, switch S 6 and switch S 9 turn off, electric capacity C4 two ends be connected respectively to and reference voltage Vref, now the voltage at electric capacity C4 two ends is charged to reference voltage Vref, as shown in Figure 7 B; Second state, switch S 7 and switch S 8 turn off, switch S 6 and switch S 9 conducting, electric capacity C4 two ends are connected respectively to source electrode and the grid of depletion field effect transistor M2, now the grid voltage Vg of depletion field effect transistor M2 is that source voltage Vs adds reference voltage Vref, thus achieve bootstrapping function, reduce the conducting resistance of depletion field effect transistor M2, larger electric current can be provided to bypass control circuit 202.
Second embodiment
With reference to figure 8, Fig. 8 shows the LED dimming driving circuit of the second embodiment, shown in its overall structure with Fig. 2, the first embodiment is substantially identical, its difference is, in second embodiment, bypass common circuit 1051 in bypass composite device is only integrated with bypass and function of supplying power, and start-up circuit 801 can be enhancement mode field effect transistor or depletion field effect transistor independent of bypass composite device and output current control circuit 105, field effect transistor M2.
Furthermore, in circuit working process, when field effect transistor M2 conducting, ac input signal VAC forms the charging path to power end Vcc via field effect transistor M2 and bypass common circuit 1051, also namely, bypass common circuit 1051 only controls the charged state of power end Vcc in circuit working process.And in start-up course, realized the charging of power end Vcc by start-up circuit 801.Such as, start-up circuit 801 can use high-voltage starting circuit to realize quick startup, or also can adopt resistance starting to reduce costs.
The internal structure of bypass common circuit 1051 is identical with the first embodiment, repeats no more here.For the operation principle of bypass common circuit 1051, no longer charge to power end Vcc except when starting, other also with the first embodiments are identical.
3rd embodiment
With reference to figure 9, Fig. 9 shows the LED dimming driving circuit of the 3rd embodiment, shown in its overall structure with Fig. 2, the first embodiment is substantially identical, its difference is, in 3rd embodiment, bypass common circuit 1051 in bypass composite device is only integrated with bypass and start-up performance, and power supply circuits 901 are still depletion field effect transistor independent of bypass composite device and output current control circuit 105, field effect transistor M2.
Furthermore, in circuit start process, field effect transistor M2 conducting, ac input signal VAC forms the charging path to power end Vcc via field effect transistor M2 and bypass common circuit 1051, also namely, bypass common circuit 1051 only controls the charged state of power end Vcc in circuit start process.And in circuit working process, realized the charging of power end Vcc by power supply circuits 901.Power supply circuits 901 can use any suitable power supply circuit construction in prior art.
The internal structure of bypass common circuit 1051 is identical with the first embodiment, repeats no more here.For the operation principle of bypass common circuit 1051, except no longer charging to power end Vcc when circuit working, other also with the first embodiments are identical.
To sum up, present embodiments provide bypass composite device, in the LED drive circuit of band dimmer, bypass circuit and startup, power supply circuits are integrated, this composite device can either realize high-voltage high-speed start-up performance, the power supply of output current control circuit under holding state can be realized again, the bypass circuit function under normal operating conditions and holding state can also be realized, the normal work of dimmer can be ensured.
The above is only preferred embodiment of the present utility model, not does any pro forma restriction to the utility model.Therefore, every content not departing from technical solutions of the utility model, just according to technical spirit of the present utility model to any simple amendment made for any of the above embodiments, equivalent conversion, all still belong in the protection range of technical solutions of the utility model.
Claims (37)
1. a bypass composite device, is characterized in that, comprising:
Field effect transistor, its drain electrode connects high voltage input terminal;
Bypass common circuit, receive dim signal and by-passing signal, connect grid and the source electrode of power end and described field effect transistor, the operating state of described field effect transistor is controlled according to the supply voltage of described dim signal and described power end, regulate the bypass impedance between the source electrode of described field effect transistor and ground according to described by-passing signal, control the charged state to described power end in startup and/or the course of work according to described dim signal and described supply voltage.
2. device according to claim 1, is characterized in that, described high voltage input terminal forms the bypass path between ground via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
3. device according to claim 1, is characterized in that, described high voltage input terminal forms the charging path between described power end via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
4. device according to claim 1, is characterized in that, described bypass common circuit controls the charged state of power end described in startup and the course of work according to described dim signal and described supply voltage.
5. device according to claim 1, is characterized in that, described bypass common circuit controls the charged state of power end described in the course of work according to described dim signal and described supply voltage.
6. device according to claim 1, is characterized in that, described bypass common circuit controls the charged state of power end described in start-up course according to described dim signal and described supply voltage.
7. device according to any one of claim 1 to 6, is characterized in that, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal.
8. device according to claim 7, is characterized in that, described bypass control circuit comprises one or more impedance path, and described impedance path comprises:
Switch, its first end connects the source electrode of described field effect transistor;
Impedance, its first end connects the second end of described switch, its second end ground connection;
Wherein, the turn-on and turn-off of described switch are controlled by described by-passing signal.
9. device according to claim 7, is characterized in that, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
First switching tube, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its second end connects described power end, and its control end connects the drain electrode of described metal-oxide-semiconductor;
First resistance, its first end connects the first end of described first switching tube, and its second end connects the control end of described first switching tube.
10. device according to claim 7, is characterized in that, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
Second switch pipe, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its control end connects the drain electrode of described metal-oxide-semiconductor;
3rd switching tube, its first end connects the control end of described second switch pipe, and its control end connects the second end of described second switch pipe;
Second resistance, its first end connects the first end of described second switch pipe, and its second end connects the control end of described second switch pipe;
3rd resistance, its first end connects the control end of described 3rd switching tube, and its second end connects the second end of described 3rd switching tube;
Anti-discharge diode, its anode connects the second end of described 3rd switching tube, and its negative electrode connects described power end.
11. devices according to claim 4, is characterized in that, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal;
Wherein, described gate voltage control circuit comprises:
First switch, its first end connects the grid of described field effect transistor, and its second end is via the 4th grounding through resistance;
Second switch, its first end connects the grid of described field effect transistor, and its second termination receives grid bootstrap voltage mode, and described grid bootstrap voltage mode equals the source voltage of described field effect transistor and the reference voltage sum preset;
3rd switch, its first end connects the grid of described field effect transistor, and its second end is connected to the source electrode of described field effect transistor via the 5th resistance;
Wherein, the turn-on and turn-off of described first switch, second switch and the 3rd switch are controlled by described supply voltage and dim signal.
12. devices according to claim 11, is characterized in that, described gate voltage control circuit also comprises grid boostrap circuit, and for generation of described grid bootstrap voltage mode, described grid boostrap circuit comprises:
4th switch, its first end connects the grid of described field effect transistor;
5th switch, its first end receives described reference voltage;
Electric capacity, its first end connects the second end of described 4th switch and the second end of the 5th switch;
6th switch, its first end connects the second end of described electric capacity, its second end ground connection;
7th switch, its first end connects the second end of described electric capacity, and its second end connects the source electrode of described field effect transistor.
13. devices according to claim 1, is characterized in that, described power end is configured to be connected with the first end of electric capacity of powering, the second end ground connection of described power supply electric capacity.
14. devices according to claim 4, is characterized in that, described field effect transistor is depletion field effect transistor.
15. devices according to claim 5, is characterized in that, described field effect transistor is enhancement mode field effect transistor or depletion field effect transistor.
16. devices according to claim 6, is characterized in that, described field effect transistor is depletion field effect transistor.
17. 1 kinds of output current control circuits, is characterized in that, comprising:
Bypass composite device, described bypass composite device comprises:
Field effect transistor, its drain electrode connects high voltage input terminal;
Bypass common circuit, receive dim signal and by-passing signal, connect grid and the source electrode of power end and described field effect transistor, the operating state of described field effect transistor is controlled according to the supply voltage of described dim signal and described power end, regulate the bypass impedance between the source electrode of described field effect transistor and ground according to described by-passing signal, control the charged state to described power end in startup and/or the course of work according to described dim signal and described supply voltage;
Dim signal produces circuit, for the dimming state of detection control unit to produce described dim signal;
Power control circuit, produces the control signal being used for regulating load electric current or bearing power according to described dim signal.
18. output current control circuits according to claim 17, is characterized in that, described high voltage input terminal forms the bypass path between ground via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
19. output current control circuits according to claim 17, is characterized in that, described high voltage input terminal forms the charging path between described power end via described field-effect transistor and bypass common circuit under the state of described field effect transistor conducting.
20. output current control circuits according to claim 17, is characterized in that, described bypass common circuit controls the charged state of power end described in startup and the course of work according to described dim signal and described supply voltage.
21. output current control circuits according to claim 17, is characterized in that, described bypass common circuit controls the charged state of power end described in the course of work according to described dim signal and described supply voltage.
22. output current control circuits according to claim 17, is characterized in that, described bypass common circuit controls the charged state of power end described in start-up course according to described dim signal and described supply voltage.
23., according to claim 17 to the output current control circuit according to any one of 22, is characterized in that, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal.
24. output current control circuits according to claim 23, it is characterized in that, described bypass control circuit comprises one or more impedance path, described impedance path comprises:
Switch, its first end connects the source electrode of described field effect transistor;
Impedance, its first end connects the second end of described switch, its second end ground connection;
Wherein, the turn-on and turn-off of described switch are controlled by described by-passing signal.
25. output current control circuits according to claim 23, is characterized in that, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
First switching tube, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its second end connects described power end, and its control end connects the drain electrode of described metal-oxide-semiconductor;
First resistance, its first end connects the first end of described first switching tube, and its second end connects the control end of described first switching tube.
26. output current control circuits according to claim 23, is characterized in that, described power charging circuit comprises:
Anti-diode of playing a reversed role, its anode connects the source electrode of described field effect transistor;
Metal-oxide-semiconductor, its grid receives described charging control signal, its source ground;
Second switch pipe, its first end connects the negative electrode of described anti-diode of playing a reversed role, and its control end connects the drain electrode of described metal-oxide-semiconductor;
3rd switching tube, its first end connects the control end of described second switch pipe, and its control end connects the second end of described second switch pipe;
Second resistance, its first end connects the first end of described second switch pipe, and its second end connects the control end of described second switch pipe;
3rd resistance, its first end connects the control end of described 3rd switching tube, and its second end connects the second end of described 3rd switching tube;
Anti-discharge diode, its anode connects the second end of described 3rd switching tube, and its negative electrode connects described power end.
27. output current control circuits according to claim 20, is characterized in that, described bypass common circuit comprises:
Gate voltage control circuit, produce grid voltage and charging control signal according to described supply voltage and dim signal, described grid voltage transfers to the grid of described field effect transistor;
Power charging circuit, its first end connects the source electrode of described field effect transistor, its second end connects described power end, and described power charging circuit is conducting or the charging path that turns off between the source electrode of described field effect transistor and described power end under the control of described charging control signal;
Bypass control circuit, for providing the bypass path between the source electrode of described field effect transistor and ground, and determines the bypass impedance of described bypass path according to described by-passing signal;
Wherein, described gate voltage control circuit comprises:
First switch, its first end connects the grid of described field effect transistor, and its second end is via the 4th grounding through resistance;
Second switch, its first end connects the grid of described field effect transistor, and its second termination receives grid bootstrap voltage mode, and described grid bootstrap voltage mode equals the source voltage of described field effect transistor and the reference voltage sum preset;
3rd switch, its first end connects the grid of described field effect transistor, and its second end is connected to the source electrode of described field effect transistor via the 5th resistance;
Wherein, the turn-on and turn-off of described first switch, second switch and the 3rd switch are controlled by described supply voltage and dim signal.
28. output current control circuits according to claim 27, is characterized in that, described gate voltage control circuit also comprises grid boostrap circuit, and for generation of described grid bootstrap voltage mode, described grid boostrap circuit comprises:
4th switch, its first end connects the grid of described field effect transistor;
5th switch, its first end receives described reference voltage;
Electric capacity, its first end connects the second end of described 4th switch and the second end of the 5th switch;
6th switch, its first end connects the second end of described electric capacity, its second end ground connection;
7th switch, its first end connects the second end of described electric capacity, and its second end connects the source electrode of described field effect transistor.
29. output current control circuits according to claim 17, is characterized in that, described power end is configured to be connected with the first end of electric capacity of powering, the second end ground connection of described power supply electric capacity.
30. according to claim 17 to the output current control circuit according to any one of 22,27 to 29, it is characterized in that, also comprise: by-passing signal produces circuit, in response to the Preset Time after the Preset Time before ac input signal zero passage to zero passage, described by-passing signal produces circuit and produces described by-passing signal.
31. output current control circuits according to claim 20, is characterized in that, described field effect transistor is depletion field effect transistor.
32. output current control circuits according to claim 21, is characterized in that, described field effect transistor is enhancement mode field effect transistor or depletion field effect transistor.
33. output current control circuits according to claim 22, is characterized in that, described field effect transistor is depletion field effect transistor.
34. 1 kinds of LED dimming driving circuits, is characterized in that, comprise the output current control circuit according to any one of claim 17 to 33.
35. LED dimming driving circuits according to claim 34, is characterized in that, also comprise:
Alternating current input power supplying, it has interchange input first end and exchanges input second end, and described interchange inputs the second end ground connection;
Control unit, its input connects interchange input first end;
Rectification circuit, its input first end connects the output of described control unit, and it inputs the second end and connects interchange input second end, and it exports first end and connects described high voltage input terminal;
Input filter capacitor, its first end connects the output first end of described rectification circuit, and its second end connects output second end of described rectification circuit and ground connection;
Diode, its anode connects the output plus terminal of described rectification circuit;
Power transfer circuitry, its first input end connects the negative electrode of described diode, and its second input connects the output of described power control circuit, and its output is for connecting load.
36. LED dimming driving circuits according to claim 35, it is characterized in that, described alternating current input power supplying, control unit, field effect transistor and bypass common circuit form a galvanic circle under the state of described field effect transistor conducting, and this galvanic circle is used for powering to described control unit; Disconnect under the state that described galvanic circle turns off in described field effect transistor.
37. LED dimming driving circuits according to claim 35, is characterized in that, described control unit is dimmer.
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| CN201420794746.XU CN204335061U (en) | 2014-12-15 | 2014-12-15 | LED dimming driving circuit and output current control circuit thereof and bypass composite device |
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| CN201420794746.XU CN204335061U (en) | 2014-12-15 | 2014-12-15 | LED dimming driving circuit and output current control circuit thereof and bypass composite device |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104378894A (en) * | 2014-12-15 | 2015-02-25 | 杭州士兰微电子股份有限公司 | LED dimming drive circuit and output current control circuit and bypass sharing device thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104378894A (en) * | 2014-12-15 | 2015-02-25 | 杭州士兰微电子股份有限公司 | LED dimming drive circuit and output current control circuit and bypass sharing device thereof |
| CN104378894B (en) * | 2014-12-15 | 2017-06-16 | 杭州士兰微电子股份有限公司 | LED dimming driving circuits and its output current control circuit and bypass composite device |
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