CN208300087U - LED drive control device, LED drive circuit and LED light emission device - Google Patents
LED drive control device, LED drive circuit and LED light emission device Download PDFInfo
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- CN208300087U CN208300087U CN201821007046.6U CN201821007046U CN208300087U CN 208300087 U CN208300087 U CN 208300087U CN 201821007046 U CN201821007046 U CN 201821007046U CN 208300087 U CN208300087 U CN 208300087U
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Abstract
Disclose a kind of LED drive control device and driving circuit, comprising: power tube has control terminal, first end and second end, and control terminal receives switch control signal；Zero cross detection circuit, for generating zero passage detection signal；First comparison circuit, for being compared according to reference voltage with sampled voltage to generate first control signal；Control circuit is connected with zero cross detection circuit and comparison circuit, for generating switch control signal according to zero passage detection signal and first control signal；Overvoltage crowbar, turn-off time and reference voltage for being provided according to control circuit generate overvoltage protection signal；Screened circuit keeps overvoltage protection signal invalid for being shielded according to shielded signal when power tube turns off, and resetting in power tube conducting keeps overvoltage protection signal effective.LED drive circuit enters overvoltage protection mode and flashing light when the utility model can prevent and LED load voltage lower in input voltage higher, while avoiding the occurrence of and burning lamp phenomenon.
Description
Technical field
The utility model relates to electronic technology field, in particular to a kind of LED drive control device, LED drive circuit and LED
Light emitting device.
Background technique
LED (Light Emitting Diode, light emitting diode) have long service life, small in size, power consumption is low,
The many advantages such as operating temperature is low, therefore it is widely used in LED illumination and LED shows product.
The brightness of LED light is related to driving current, and corresponding drive scheme is Linear Driving scheme and switch drive scheme.
The mode of linear regulation transistor is respectively adopted in the two and the mode of switch control transistor adjusts driving current.Fig. 1 is shown
The circuit diagram of switching mode LED drive circuit in the prior art.As shown in Figure 1, the LED drive circuit includes current rectifying and wave filtering circuit
10, power supply circuit 20, existing LED drive control device 30 and output-stage circuit 40.Current rectifying and wave filtering circuit 10 includes rectifier bridge 101
With first capacitor C1, wherein the alternating voltage AC rectifying and wave-filtering of input is DC bus-bar voltage Vin by the rectifier bridge 101, and
And it is stored in first capacitor C1.Power supply circuit 20 includes that resistance R and the second capacitor C2, DC bus-bar voltage Vin are given by resistance R
Second capacitor C2 charging, to provide stable supply voltage VCC to existing LED drive control device 30.Output-stage circuit 40 wraps
It includes inductance L, diode D and third capacitor C3, diode D is connected to the DRAIN pin and DC bus of LED drive control device 30
Between voltage Vin, inductance L is connected to the DRAIN pin of LED drive control device 30 and the output end vo ut of output-stage circuit 40
Between；Third capacitor C3 is connected between DC bus-bar voltage Vin and output end vo ut.LED load 50 includes multiple concatenated
LED is connected in parallel between DC bus-bar voltage Vin and output end vo ut.Output-stage circuit 40 is according to LED drive control device 30
The DC powered LED load 50 of output.
Fig. 2 shows the internal frame diagrams of LED drive control device in the prior art；Fig. 3 is LED driving in the prior art
The working waveform figure of controller 30.The VCC pin of the LED drive control device is energization pins, for receiving supply voltage
VCC；DRAIN pin is connected to internal switching tube Q；CS pin is sampling pin, for acquiring the electric current for flowing through switching tube Q,
It is connected with sampling resistor Rcs；GND pin is grounding pin；OVP is open-circuit-protection pin, is connected with open-circuit-protection resistance Rovp.
When the switching tube Q conducting that LED drive control device 30 is internally integrated, energy storage, inductive current I are carried out to inductance LLRise always,
When being greater than reference voltage Vref to the voltage Vcs of sampling resistor Rcs, comparator U1 exports first control signal S1 to controlling electricity
Road, for control circuit after receiving first control signal, control switch pipe Q shutdown, inductive current rises to preset threshold Ipk,
The turn-on time Ton of LED drive control device 30 is Ton=L*Ipk/ (Vin-VLED), wherein Ipk=Vref/Rcs, VLEDFor LED
Load the voltage at 50 both ends, i.e. voltage difference between Vin and Vout；When the switching tube Q that LED drive control device 30 is internally integrated is closed
When disconnected, inductance L provides energy, inductive current ILCan not instantaneous abrupt change, therefore, inductive current ILIt is gradually reduced from peak I pk, directly
To being reduced to zero, zero cross detection circuit detects inductive current I at this timeLWhen being zero, then a zero passage detection signal ZCD is sent to control
Circuit processed, so that control circuit resets, control switch pipe Q is connected, and the turn-off time Toff of LED drive control device 30 is
Toff=L*Ipk/VLED.That is, working as inductive current ILWhen being charged to a preset threshold Ipk, LED drive control device 30 is closed
Disconnected switching tube Q, as inductive current ILWhen being discharged to zero, switching tube Q is connected in LED drive control device 30, is repeated in this way
Signal.Therefore, the switching tube Q inside LED drive control device 30 switches repeatedly between switch state, so that LED driving control
The work of device 30 processed is under critical conduction mode.
Due to the presence of not no auxiliary winding, the voltage at LED light both ends can not be directly detected, way general at present is inspection
Turn-off time Toff is surveyed, is compared with internal fiducial time Tovp, as turn-off time Toff > Tovp, is worked normally；
As turn-off time Toff < Tovp, to control circuit send overvoltage protection signal OVP, into overvoltage protection mode, prevent by
LED is burnt out.
Since the alternating voltage AC of input is after rectifier bridge 101 and first capacitor C1 rectifying and wave-filtering, DC bus can be made
Voltage Vin generates biggish ripple, and especially when input voltage is smaller and the voltage of LED is larger, the minimum value of Vin is close
VLED, at this point, the turn-on time Ton of switching tube Q can be very big.The audio frequency range that general human ear can be heard be 20Hz~
20KHz shows as inductance and utters long and high-pitched sounds phenomenon if without processing, which may be heard by human ear.Inductance is solved to make a whistling sound
The method for being phenomenon is to increase maximum turn-on time circuit inside LED drive control device 30, when by maximum turn-on time
After the Ton_max time, even if inductive current ILIt is still not up to preset threshold Ipk, also turns off switching tube Q.Due to inductive current IL
Peak value it is lower, the time of turn-off time Toff can also reduce than normal corresponding, it is likely that will appear Toff < Tovp, cause into
Enter overvoltage protection mode and flashing light.
Utility model content
In view of the above problems, the purpose of this utility model is to provide a kind of LED drive control device, LED drive circuit and
LED light emission device, and LED load voltage lower in voltage input prevent from entering overvoltage protection mode and flashing light when higher.
It is according to the present utility model in a first aspect, providing a kind of LED drive control device, comprising:
Power tube has control terminal, first end and second end, and control terminal receives switch control signal, and first end is via electricity
Sense is connected with LED load, and second end is grounded via sampling resistor；
Zero cross detection circuit, input terminal connect the first end of the power tube, for generating zero passage detection signal；
First comparison circuit, for being compared according to reference voltage with sampled voltage to generate first control signal；
Control circuit is connected with the zero cross detection circuit and comparison circuit, for according to the zero passage detection signal
And the first control signal generates switch control signal, wherein the switch control signal is for controlling leading for power tube
Logical and shutdown；Overvoltage crowbar, input terminal is via overvoltage protection resistance eutral grounding, for what is provided according to the control circuit
Turn-off time and reference voltage generate overvoltage protection signal；
Screened circuit is arranged between overvoltage crowbar and control circuit, for being closed according to shielded signal in power tube
Shielding makes the overvoltage protection signal be in invalid state when disconnected, and resetting in power tube conducting believes the overvoltage protection
Number be in effective status.
Preferably, the screened circuit includes:
Shielded signal generation circuit, for generating shielded signal according to first control signal and second control signal；
Logic circuit, for shielding to make the overvoltage protection signal be in invalid when power tube turns off according to shielded signal
State, and resetting in power tube conducting makes the overvoltage protection signal be in effective status.
Preferably, the LED drive control device further include:
Second comparison circuit, turn-on time and maximum turn-on time for being provided according to the control circuit generate second
Control signal.
Preferably, when first control signal is high level pulse, and second control signal keeps low level, then shielded signal
High level is kept, overvoltage protection signal is made to be in effective status.
Preferably, when first control signal keeps low level, and second control signal is high level pulse, then shielded signal
Low level is kept, overvoltage protection signal is made to be in invalid state.
Preferably, the LED drive control device further include:
Maximum time turning circuit, for generating the maximum turn-on time.
Preferably, the LED drive control device further include:
Lead-edge-blanking circuit, for generating second control signal according to the switch control signal.
Preferably, when first control signal and second control signal are high level pulse, shielded signal is in power tube
It is high level during shutdown, is low level during power tube conducting, so that overvoltage protection signal is during power tube turns off
In effective status, it is in invalid state during power tube conducting, so that overvoltage protection signal is in during power tube turns off
Effective status is in invalid state during power tube conducting.
Preferably, when first control signal keeps low level, and second control signal is high level pulse, shielded signal is protected
Low level is held, overvoltage protection signal is made to be in invalid state.
Preferably, the shielded signal generation circuit includes the first nor gate, the second nor gate and NOT gate,
Wherein, the first input end reception second control signal of the first nor gate, the second input terminal and the second nor gate
Output end is connected, and output end is connected with the first input end of the second nor gate；
The first input end of second nor gate is connected with the output end of the first nor gate, and the second input terminal receives the first control
Signal, output end export shielded signal.
Preferably, the logic circuit is NAND gate.
Preferably, first comparison circuit includes:
Reference voltage generates unit, for generating reference voltage according to supply voltage；
First comparing unit, for generating first control signal according to reference voltage and sampled voltage.
Preferably, the overvoltage crowbar includes:
Fiducial time unit, for generating fiducial time according to reference voltage；
Second comparing unit, turn-off time and fiducial time for being provided according to the control circuit generate overvoltage protection
Signal.
Another aspect according to the present utility model provides a kind of LED drive circuit, including LED as described above driving control
Device processed.
The third aspect according to the present utility model provides a kind of LED light emission device, including LED as described above driving electricity
Road and LED load.
LED drive control device, LED drive circuit and LED light emission device provided by the utility model, in overvoltage crowbar
Screened circuit is provided between control circuit, the screened circuit makes overvoltage protection according to shielded signal when power tube is turned off
Circuit is in invalid state, and LED drive circuit enters overvoltage protection when preventing and LED load voltage lower in input voltage higher
Mode and flashing light.Further, screened circuit is resetted when power tube is connected, so that the normal work of overvoltage crowbar
Make, avoids the occurrence of and burn lamp phenomenon.
Detailed description of the invention
By referring to the drawings to the description of the utility model embodiment, above-mentioned and other mesh of the utility model
, feature and advantage will be apparent from, in the accompanying drawings:
Fig. 1 shows the circuit diagram of switching mode LED drive circuit in the prior art；
Fig. 2 shows the internal frame diagrams of LED drive control device shown in FIG. 1；
Fig. 3 shows the work wave schematic diagram of LED drive control device shown in FIG. 1；
Fig. 4 shows the internal frame diagram of the LED drive control device of the utility model first embodiment offer；
Fig. 5 shows the circuit of the screened circuit of the LED drive control device provided according to the utility model first embodiment
Figure；
Fig. 6 a and Fig. 6 b respectively illustrate the letter when LED drive control device work of the utility model second embodiment offer
Number waveform diagram；
Fig. 7 shows the internal frame diagram of the LED drive control device of the utility model second embodiment offer；
Fig. 8 shows the circuit diagram of the screened circuit of the LED drive control device of the utility model second embodiment offer；
Fig. 9 a and Fig. 9 b respectively illustrate the letter when LED drive control device work of the utility model second embodiment offer
Number waveform diagram.
Specific embodiment
Hereinafter reference will be made to the drawings is more fully described the various embodiments of the utility model.In various figures, identical
Element is indicated using same or similar appended drawing reference.For the sake of clarity, the various pieces in attached drawing are not drawn to draw
System.
With reference to the accompanying drawings and examples, specific embodiment of the present utility model is described in further detail.
Fig. 4 shows the internal frame diagram of the LED drive control device of the utility model first embodiment offer.As shown in figure 4,
The LED drive control device 30 includes power tube Q, zero cross detection circuit 31, the first comparison circuit 32, control circuit 33, over-voltage
Protect circuit 34 and screened circuit 35.
Wherein, power tube Q has control terminal, first end and second end, and control terminal receives switch control signal SQ, first end
It is connected via inductance L with LED load, second end is grounded via sampling resistor Rcs.
In the present embodiment, LED drive control device 30 includes supply port Vcc, is used for the LED drive control device 30
Supply voltage is provided；Ground port GND, provides inner ground for LED chip；The port DRAIN, via inductance L and LED load phase
Even；Sample port CS is connected, for the inductive current I to inductance L with ground port GND via sampling resistor RcsLIt is sampled,
Wherein, the pressure drop of sampling resistor Rcs generation will be flowed through as sampled voltage Vcs；Overvoltage protection port OVP, via overvoltage protection
Resistance Rovp is connected with ground port GND.The first end of power tube is connected with the port DRAIN, and second end is connected with sample port CS.
Zero cross detection circuit 31, input terminal connect the first end of the power tube, for generating zero passage detection signal
ZCD。
In the present embodiment, its input terminal of zero cross detection circuit 31 is connect with the first end of power tube Q, i.e., drives with LED
The port DRAIN of controller 30 is connected, for detecting the inductive current I of inductance LL, and generate zero passage detection signal.Wherein, when
Detect the inductive current ILWhen being 0, switch control signal SQ that control circuit 33 is generated according to the zero passage detection signal
For Continuity signal, the power tube Q conducting is controlled.
First comparison circuit 32 is for comparing according to reference voltage with sampled voltage to generate first control signal.
In the present embodiment, first comparison circuit 32 includes that reference voltage generates unit 321 and the first comparing unit
322, wherein the reference voltage generates unit 321 and is used to generate reference voltage Vref according to supply voltage Vcc；First compares
Unit 322, first input end receive reference voltage Vref, and the second input terminal receives sampled voltage Vcs, output end output first
Control signal S1.When sampled voltage Vcs is greater than reference voltage Vref, control circuit 33 is generated according to first control signal S1
Switch control signal SQ is cut-off signals, controls the power tube Q shutdown.
Control circuit 33 is connected with the zero cross detection circuit 31 and the first comparison circuit 32, for according to the mistake
The zero detection signal ZCD and first control signal S1 generates switch control signal SQ, wherein the switch control signal SQ
For controlling the conducting and shutdown of power tube Q.
Overvoltage crowbar 34, input terminal are grounded via overvoltage protection resistance Rovp, for according to the control circuit
The 33 turn-off time Toff provided and reference voltage Vovp generate overvoltage protection signal OVP.
In the present embodiment, the overvoltage crowbar 34 includes fiducial time unit 341 and the second comparing unit 342,
Wherein, fiducial time unit 321 is used to generate fiducial time Tovp according to reference voltage Vovp；Second comparing unit 342 is used for
The turn-off time Toff provided according to the control circuit and fiducial time Tovp generate overvoltage protection signal OVP.As Toff <
When Tovp, control circuit 33 controls power tube Q according to overvoltage protection signal OVP and turns off, into overvoltage protection mode.
Screened circuit 35 is arranged between overvoltage crowbar 34 and control circuit 33, for the root in power tube Q shutdown
The overvoltage protection signal OVP is set to be in invalid state according to shielded signal SS, and reset makes the mistake in power tube Q conducting
Pressure protection signal OVP is in effective status.
LED drive control device is as shown in figure 5, the screened circuit 35 includes shielded signal generation circuit 351 and logic electricity
Road 352, wherein the shielded signal generation circuit 351 is used to be generated according to first control signal S1 and second control signal S2
Shielded signal SS；Logic circuit 352, which is used to be shielded according to shielded signal SS when power tube Q is turned off, makes the overvoltage protection signal
OVP is in invalid state, and resetting in power tube Q conducting makes the overvoltage protection signal OVP be in effective status.
In a preferred embodiment, the shielded signal generation circuit 351 includes two nor gates NOR1 and NOR2
And NOT gate NOT；Wherein, the first input end of nor gate NOR1 receives second control signal S2, the second input terminal AND OR NOT gate
The output end of NOR2 is connected, and the first input end of output end AND OR NOT gate NOR2 is connected；The second input termination of nor gate NOR2
First control signal S1 is received, output end exports shielded signal SS.Logic circuit 352 includes NAND gate NAND, wherein NAND gate
The first input end of NAND receives shielded signal SS, and the second input terminal receives overvoltage protection signal OVP, output end and control circuit
33 are connected.
In a preferred embodiment, the LED drive control device further includes the second comparison circuit 36 and maximum time
Turning circuit 37.Wherein, the second comparison circuit 36, turn-on time Ton and maximum for being provided according to the control circuit are led
Logical time Ton-max generates second control signal S2.Maximum time turning circuit 37, for generating the maximum turn-on time
Ton-max.As Ton > Ton-max, the second comparison circuit 36 exports second control signal S2.
Fig. 6 a and Fig. 6 b respectively illustrate the letter when LED drive control device work of the utility model first embodiment offer
Number waveform diagram.As shown in Figure 6 a, when first control signal S1 is high level pulse, and second control signal S2 keeps low level,
Then shielded signal SS keeps high level, and overvoltage protection signal OVP is made to be in effective status.In this case, LED load is underloading
State, inductive current are bigger, it may appear that sampled voltage Vcs is greater than the case where reference voltage Vref, therefore, first control signal
S1 is high level pulse, and the turn-on time of power tube is always less than maximum turn-on time i.e. (Ton < Ton-max), so the
Two control signal S2 keep low level.Shielded signal SS keeps high level at this time, and overvoltage protection signal OVP is made to be in effective always
State.
As shown in Figure 6 b, when first control signal S1 keeps low level, and second control signal S2 is high level pulse, then
Shielded signal SS keeps low level, and overvoltage protection signal OVP is made to be in invalid state.In this case, LED load is heavily loaded shape
State, inductive current is smaller, is not in the case where sampled voltage Vcs is greater than reference voltage Vref, therefore, first control signal
S1 keeps low level, then will appear the case where turn-on time of power tube is greater than maximum turn-on time, so second control signal
S2 is high level pulse.Shielded signal SS keeps low level at this time, and overvoltage protection signal OVP is made to be in invalid state always.
The utility model first embodiment provides LED drive control device, sets between overvoltage crowbar and control circuit
It is equipped with screened circuit, the screened circuit makes overvoltage crowbar be in invalid shape when power tube is turned off according to shielded signal
State, LED drive circuit enters overvoltage protection mode and flashing light when preventing and LED load voltage lower in input voltage higher.Into
One step, screened circuit is resetted in power tube conducting, so that overvoltage crowbar works normally, avoids the occurrence of burning lamp
Phenomenon.
Fig. 7 shows the internal frame diagram of the LED drive control device of the utility model second embodiment offer.As shown in fig. 7,
The LED drive control device 30 includes power tube Q, zero cross detection circuit 31, the first comparison circuit 32, control circuit 33, over-voltage
Protect circuit 34 and screened circuit 35.
Wherein, power tube Q has control terminal, first end and second end, and control terminal receives switch control signal SQ, first end
It is connected via inductance L with LED load, second end is grounded via sampling resistor Rcs.
In the present embodiment, LED drive control device 30 includes supply port Vcc, is used for the LED drive control device 30
Supply voltage is provided；Ground port GND, provides inner ground for LED chip；The port DRAIN, via inductance L and LED load phase
Even；Sample port CS is connected, for the inductive current I to inductance L with ground port GND via sampling resistor RcsLIt is sampled,
Wherein, the pressure drop of sampling resistor Rcs generation will be flowed through as sampled voltage Vcs；Overvoltage protection port OVP, via overvoltage protection
Resistance Rovp is connected with ground port GND.The first end of power tube is connected with the port DRAIN, and second end is connected with sample port CS.
Zero cross detection circuit 31, input terminal connect the first end of the power tube, for generating zero passage detection signal
ZCD。
In the present embodiment, its input terminal of zero cross detection circuit 31 is connect with the first end of power tube Q, i.e., drives with LED
The port DRAIN of controller 30 is connected, for detecting the inductive current I of inductance LL, and generate zero passage detection signal.Wherein, when
Detect the inductive current ILWhen being 0, switch control signal SQ that control circuit 33 is generated according to the zero passage detection signal
For Continuity signal, the power tube Q conducting is controlled.
First comparison circuit 32 is for comparing according to reference voltage with sampled voltage to generate first control signal.
In the present embodiment, first comparison circuit 32 includes that reference voltage generates unit 321 and the first comparing unit
322, wherein the reference voltage generates unit 321 and is used to generate reference voltage Vref according to supply voltage Vcc；First compares
Unit 322, first input end receive reference voltage Vref, and the second input terminal receives sampled voltage Vcs, output end output first
Control signal S1.When sampled voltage Vcs is greater than reference voltage Vref, control circuit 33 is generated according to first control signal S1
Switch control signal SQ is cut-off signals, controls the power tube Q shutdown.
Control circuit 33 is connected with the zero cross detection circuit 31 and the first comparison circuit 32, for according to the mistake
The zero detection signal ZCD and first control signal S1 generates switch control signal SQ, wherein the switch control signal SQ
For controlling the conducting and shutdown of power tube Q.
Overvoltage crowbar 34, input terminal are grounded via overvoltage protection resistance Rovp, for according to the control circuit
The 33 turn-off time Toff provided and reference voltage Vovp generate overvoltage protection signal OVP.
In the present embodiment, the overvoltage crowbar 34 includes fiducial time unit 341 and the second comparing unit 342,
Wherein, fiducial time unit 321 is used to generate fiducial time Tovp according to reference voltage Vovp；Second comparing unit 342 is used for
The turn-off time Toff provided according to the control circuit and fiducial time Tovp generate overvoltage protection signal OVP.As Toff <
When Tovp, control circuit 33 controls power tube Q according to overvoltage protection signal OVP and turns off, into overvoltage protection mode.
Screened circuit 35 is arranged between overvoltage crowbar 34 and control circuit 33, for the root in power tube Q shutdown
The overvoltage protection signal OVP is set to be in invalid state according to shielded signal SS, and reset makes the mistake in power tube Q conducting
Pressure protection signal OVP is in effective status.
As shown in figure 8, the screened circuit 35 includes shielded signal generation circuit 351 and logic circuit 352, wherein institute
Shielded signal generation circuit 351 is stated for generating shielded signal SS according to first control signal S1 and second control signal S2；It patrols
Collecting circuit 352 and being used to be shielded according to shielded signal SS when power tube Q is turned off makes the overvoltage protection signal OVP be in invalid shape
State, and resetting in power tube Q conducting makes the overvoltage protection signal OVP be in effective status.
In a preferred embodiment, the shielded signal generation circuit 351 includes two nor gates NOR1 and NOR2
And NOT gate NOT；Wherein, the first input end of nor gate NOR1 receives second control signal S2, the second input terminal AND OR NOT gate
The output end of NOR2 is connected, and the first input end of output end AND OR NOT gate NOR2 is connected；The second input termination of nor gate NOR2
First control signal S1 is received, output end exports shielded signal SS.Logic circuit 352 includes NAND gate NAND, wherein NAND gate
The first input end of NAND receives shielded signal SS, and the second input terminal receives overvoltage protection signal OVP, output end and control circuit
33 are connected.
In a preferred embodiment, the LED drive control device further includes lead-edge-blanking circuit 38, for according to institute
It states switch control signal SQ and generates second control signal S2.When power tube Q conducting, lead-edge-blanking circuit 38 can generate a height
The pulse of level.
In a preferred embodiment, the lead-edge-blanking circuit 38 is also used to according to the zero passage detection signal ZCD
Generate second control signal S2.
Fig. 9 a and Fig. 9 b respectively illustrate the letter when LED drive control device work of the utility model second embodiment offer
Number waveform diagram.
As illustrated in fig. 9, when first control signal and second control signal are high level pulse, shielded signal is in function
Rate pipe is high level during turning off, and is low level during power tube conducting, so that overvoltage protection signal turns off the phase in power tube
Between be in effective status, power tube conducting during be in invalid state.In this case, LED load is light condition, inductance
Electric current is bigger, it may appear that sampled voltage Vcs is greater than the case where reference voltage Vref, and therefore, first control signal S1 is high electricity
Flat pulse, so that power tube Q is turned off；Second control signal S2 is the high level pulse generated in the moment of power tube Q conducting, and
The high level pulse of first control signal S1 is located at the shutdown moment of power tube Q, the high level pulse position of second control signal S2
In the conducting moment of power tube Q.Shielded signal SS is high level during power tube Q shutdown at this time, during power tube Q conducting
For low level, so that overvoltage protection signal OVP is in effective status during power tube Q is turned off, during power tube Q conducting
In invalid state.
As shown in figure 9b, when first control signal S1 keeps low level, and second control signal S2 is high level pulse, then
Shielded signal SS keeps low level, and overvoltage protection signal OVP is made to be in invalid state.In this case, LED load is heavily loaded shape
State, inductive current is smaller, is not in the case where sampled voltage Vcs is greater than reference voltage Vref, therefore, first control signal
S1 keeps low level, and second control signal S2 is the high level pulse generated in the moment of power tube Q conducting.Shielded signal at this time
SS keeps low level, and overvoltage protection signal OVP is made to be in invalid state always.
The utility model second embodiment provides LED drive control device, sets between overvoltage crowbar and control circuit
It is equipped with screened circuit, the screened circuit makes overvoltage crowbar be in invalid shape when power tube is turned off according to shielded signal
State, LED drive circuit enters overvoltage protection mode and flashing light when preventing and LED load voltage lower in input voltage higher.Into
One step, screened circuit is resetted in power tube conducting, so that overvoltage crowbar works normally, avoids the occurrence of burning lamp
Phenomenon.
The utility model additionally provides a kind of LED drive circuit, including LED drive control device as described above.
The utility model additionally provides a kind of LED light emission device, including LED drive circuit as described above.
It is as described above according to the embodiments of the present invention, these embodiments details all there is no detailed descriptionthe,
Also not limiting the utility model is only the specific embodiment.Obviously, as described above, many modification and change can be made
Change.These embodiments are chosen and specifically described to this specification, is in order to preferably explain the principles of the present invention and actually to answer
With so that skilled artisan be enable to utilize the utility model and repairing on the basis of the utility model well
Change use.The utility model is limited only by the claims and their full scope and equivalents.
Claims (15)
1. a kind of LED drive control device characterized by comprising
Power tube, have control terminal, first end and second end, control terminal receive switch control signal, first end via inductance with
LED load is connected, and second end is grounded via sampling resistor；
Zero cross detection circuit, input terminal connect the first end of the power tube, for generating zero passage detection signal；
First comparison circuit, for being compared according to reference voltage with sampled voltage to generate first control signal；
Control circuit is connected with the zero cross detection circuit and comparison circuit, for according to the zero passage detection signal and
The first control signal generates switch control signal, wherein the switch control signal be used to control the conducting of power tube with
Shutdown；Overvoltage crowbar, shutdown of the input terminal via overvoltage protection resistance eutral grounding, for being provided according to the control circuit
Time and reference voltage generate overvoltage protection signal；
Screened circuit is arranged between overvoltage crowbar and control circuit, is used for according to shielded signal when power tube turns off
Shielding makes the overvoltage protection signal be in invalid state, and reset makes at the overvoltage protection signal in power tube conducting
In effective status.
2. LED drive control device according to claim 1, which is characterized in that the screened circuit includes:
Shielded signal generation circuit, for generating shielded signal according to first control signal and second control signal；
Logic circuit, for shielding to make the overvoltage protection signal be in invalid shape when power tube turns off according to shielded signal
State, and resetting in power tube conducting makes the overvoltage protection signal be in effective status.
3. LED drive control device according to claim 2, which is characterized in that further include:
Second comparison circuit, turn-on time and maximum turn-on time for being provided according to the control circuit generate the second control
Signal.
4. LED drive control device according to claim 3, which is characterized in that when first control signal be high level pulse,
When second control signal keeps low level, then shielded signal keeps high level, and overvoltage protection signal is made to be in effective status.
5. LED drive control device according to claim 3, which is characterized in that when first control signal keeps low level, the
When two control signals are high level pulse, then shielded signal keeps low level, and overvoltage protection signal is made to be in invalid state.
6. LED drive control device according to claim 4, which is characterized in that further include:
Maximum time turning circuit, for generating the maximum turn-on time.
7. LED drive control device according to claim 2, which is characterized in that further include:
Lead-edge-blanking circuit, for generating second control signal according to the switch control signal.
8. LED drive control device according to claim 7, which is characterized in that when first control signal and the second control letter
When number being high level pulse, shielded signal is high level during power tube turns off, and is low level during power tube conducting,
So that overvoltage protection signal is in effective status during power tube turns off, invalid state is in during power tube conducting.
9. LED drive control device according to claim 7, which is characterized in that when first control signal keeps low level, the
When two control signals are high level pulse, shielded signal keeps low level, and overvoltage protection signal is made to be in invalid state.
10. LED drive control device according to claim 2, which is characterized in that the shielded signal generation circuit includes the
One nor gate, the second nor gate and NOT gate,
Wherein, the first input end of the first nor gate receives second control signal, the output of the second input terminal and the second nor gate
End is connected, and output end is connected with the first input end of the second nor gate；
The first input end of second nor gate is connected with the output end of the first nor gate, and the second input terminal receives the first control letter
Number, output end exports shielded signal.
11. LED drive control device according to claim 2, which is characterized in that the logic circuit is NAND gate.
12. LED drive control device according to claim 1, which is characterized in that first comparison circuit includes:
Reference voltage generates unit, for generating reference voltage according to supply voltage；
First comparing unit, for generating first control signal according to reference voltage and sampled voltage.
13. LED drive control device according to claim 1, which is characterized in that the overvoltage crowbar includes:
Fiducial time unit, for generating fiducial time according to reference voltage；
Second comparing unit, turn-off time and fiducial time for being provided according to the control circuit generate overvoltage protection letter
Number.
14. a kind of LED drive circuit, including current rectifying and wave filtering circuit, output-stage circuit and any one of such as claim 1-13
The LED drive control device.
15. a kind of LED light emission device, which is characterized in that including LED drive circuit as claimed in claim 14 and LED load.
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| CN201821007046.6U CN208300087U (en) | 2018-06-27 | 2018-06-27 | LED drive control device, LED drive circuit and LED light emission device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108650744A (en) * | 2018-06-27 | 2018-10-12 | 北京集创北方科技股份有限公司 | LED drive control devices, LED drive circuit and LED light emission device |
| CN110461064A (en) * | 2019-08-19 | 2019-11-15 | 芯好半导体(成都)有限公司 | A kind of LED drive circuit, LED driving method and LED illumination device |
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2018
- 2018-06-27 CN CN201821007046.6U patent/CN208300087U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108650744A (en) * | 2018-06-27 | 2018-10-12 | 北京集创北方科技股份有限公司 | LED drive control devices, LED drive circuit and LED light emission device |
| WO2020001262A1 (en) * | 2018-06-27 | 2020-01-02 | 北京集创北方科技股份有限公司 | Led drive controller, led drive circuit, and led light-emitting device |
| US10952300B2 (en) | 2018-06-27 | 2021-03-16 | Chipone Technology (Beijing) Co., Ltd. | LED driver and controller thereof, and LED lighting device |
| CN108650744B (en) * | 2018-06-27 | 2024-05-03 | 北京集创北方科技股份有限公司 | LED driving controller, LED driving circuit and LED light-emitting device |
| CN110461064A (en) * | 2019-08-19 | 2019-11-15 | 芯好半导体(成都)有限公司 | A kind of LED drive circuit, LED driving method and LED illumination device |
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