CN102143640B - LED (light-emitting diode) drive control circuit - Google Patents
LED (light-emitting diode) drive control circuit Download PDFInfo
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- CN102143640B CN102143640B CN2011101026560A CN201110102656A CN102143640B CN 102143640 B CN102143640 B CN 102143640B CN 2011101026560 A CN2011101026560 A CN 2011101026560A CN 201110102656 A CN201110102656 A CN 201110102656A CN 102143640 B CN102143640 B CN 102143640B
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Abstract
The invention discloses a LED (light-emitting diode) drive control circuit, which comprises an LED load sampling port, a switch port and a comparison port. An error amplifier module compares the LED load sampling voltage with the reference voltage and amplifies the LED load sampling voltage; a comparison module feeds the voltage of the comparison port and the current sampling signal to a logic processing module after comparing the voltage of the comparison port and the current sampling signal are compared; an open circuit detection protection module detects whether a LED load is open-circuited, detects the duration of the open circuit and outputs the open circuit status signal, an output for a first output end of the open circuit detection protection module and an output of the error amplifier module commonly control the voltage of the comparison port, and a second output end of the open circuit detection protection module outputs the current limiting threshold; a current limiting module feeds the current limiting threshold and the current sampling signal to the logic processing module after the current limiting threshold and the current sampling signal are compared; the logic processing module processes the logic of an input, and the output controls the switch of a power tube through a drive module. The LED drive control circuit prevents the current of an inductor of the LED drive circuit from rapidly rising and avoids the LED load and the power tube being burnt after the LED load is switched on.
Description
Technical field
The present invention relates to the LED Drive Control Technique, relate in particular to the LED load open circuit protection technology of the LED drive circuit under the fixed switching frequency decompression mode.
Background technology
At present, at LED drive circuit, can be divided into boost mode and decompression mode according to the topological difference in periphery, whether change and can be divided into fixed switching frequency and variable power switch frequency according to switching frequency.In the LED Drive and Control Circuit of general employing boost mode, the designer can take load open circuit protection to prevent that output voltage is out of control.But in general decompression mode LED drive circuit, particularly in high-power LED drive circuit, extensively adopt the LED Drive and Control Circuit of fixed switching frequency decompression mode, after load open circuit, chip internal is not taked any detection action, the LED Drive and Control Circuit 11 as shown in Figure 1, comprising:
LED load sample port FB, switch port SW, comparison port COMP;
Error amplification module 12: described error amplification module 12 is by LED load sample port FB input LED load sampled voltage, and the same reference voltage of LED load sampled voltage compares and amplifies;
Comparison module 13, the current sampling signal of voltage and current sample module 110 outputs of 13 couples of comparison port COMP of described comparison module compares, and comparative result offers logic processing module 14;
Logic processing module 14, described logic processing module 14 is input clock signal, the output signal of current limliting module 17, the output signal of comparison module 13 respectively, and above-mentioned input is carried out to logical process, and the output of logic processing module 14 offers driver module 18;
Compare the external electric capacity of port, the other end ground connection of electric capacity, will compare port voltage by electric capacity and carry out filtering.
Fig. 2 is the specific embodiment of LED Drive and Control Circuit shown in Figure 1.
After above-mentioned LED drive circuit open circuit, when the LED load open circuit after a period of time duration, relatively the voltage of port COMP continues to rise, its oscillogram as shown in Figure 3, if connect the LED load, especially when input voltage VIN is higher, external inductors electric current moment is flushed to very high, until the LED drive circuit loop adjustment is to stationary value, and the high inductive current of moment likely damages LED load and power tube.
Summary of the invention
The present invention overcomes the defect existed in above-mentioned prior art, has proposed a kind of LED Drive and Control Circuit, and this LED Drive and Control Circuit has realized the load open circuit protection of the LED drive circuit under the fixed switching frequency decompression mode.
The LED Drive and Control Circuit comprises:
LED load sample port, switch port, comparison port;
The error amplification module: described error amplification module is by LED load sample port input LED load sampled voltage, and the same reference voltage of LED load sampled voltage compares and amplifies;
The current sample module, described current sample module is sampled to the electric current that flows through power tube in switch module, and the current sampling signal of output offers comparison module and current limliting module;
Comparison module, described comparison module compares the current sampling signal of the relatively voltage and current sample module output of port, and comparative result offers logic processing module; Open circuit detects protection module, comprises open circuit detection module and open-circuit-protection module,
The control signal of the power tube of the second input input switch module of described open circuit detection module, detect the LED load and whether open a way, and the duration of open circuit, the output open circuit status signal, when the duration of open circuit, surpass Preset Time, described output open circuit status signal is effective;
The open-circuit-protection module, described open-circuit-protection module receives the open-circuit condition signal, the first output output of open-circuit-protection module is with the output acting in conjunction of error amplification module in port relatively, and control ratio is than the voltage of port, the second output output one current limit threshold of open-circuit-protection module;
The mode whether described open circuit detection module the second input detection LED load opens a way is: the control signal of the power tube of switch module is input to the second input, or directly inputs the detection signal at LED load two ends;
The current limliting module, the current sampling signal of the current limit threshold of described current limliting module open-circuit protection module output and the output of current sample module compares, and comparative result offers logic processing module;
Logic processing module, described logic processing module output signal, the open circuit of input clock signal, current limliting module respectively detects the open-circuit condition signal of protection module output, the output signal of comparison module, and above-mentioned input is carried out to logical process, the output of logic processing module offers driver module;
Driver module, the power tube control end of described driver module driving switch module;
Switch module, the output connecting valve port of described switch module.
After LED drive circuit powers on, clocking, the first input end of the open circuit detection protection module of LED Drive and Control Circuit detects the control signal of the power tube of switch module, and the current limliting module is output as zero;
When the duration of LED load open circuit, be less than Preset Time, the LED Drive and Control Circuit is by comparing port to capacitor charging, described electric capacity is connected between comparison port and ground, relatively port voltage continues to rise, open circuit detects second output output the first level of protection module, and power tube control end signal is effective, and current sampling signal is zero, open a way and detect the open-circuit condition invalidating signal of protection module output, the first output that open circuit detects protection module does not act on comparing port;
When the duration of LED load open circuit, surpass Preset Time, the open-circuit condition signal of open circuit detection protection module output is effective, cause opening a way the first output of detecting protection module with the output acting in conjunction of error amplification module in port relatively, relatively port voltage is reduced to zero, the second output that open circuit detects protection module is reduced to second electrical level from the first level, the output signal of comparison module is invalid, and logic processing module only subject clock signal is controlled;
After the LED load is connected, the inductive current of LED drive circuit rises, the current sample module detects current sampling signal, current limit threshold and current sampling signal that described current limliting module open-circuit detects protection module output compare, comparative result offers logic processing module, the output signal of logic processing module resets, reset signal is turn-offed by driver module power ratio control pipe, open circuit detect protection module detect the power tube control signal invalid after, the open-circuit condition invalidating signal of output, the first output that open circuit detects protection module is not acting on the comparison port, open circuit detects second output output the first level of protection module, relatively port voltage rises gradually from zero, after this by the set of clock signal control logic processing module, the power tube conducting, when the comparison module output signal is effective, the control logic processing module resets, power tube turn-offs.
Beneficial effect of the present invention is: due to the open-circuit-protection module when the open-circuit condition signal is effective; relatively port voltage is reduced to zero; and current limit threshold is reduced to second electrical level; thereby after preventing that the LED load from connecting; electric current on the LED drive circuit inductance raises fast, avoids LED load and power tube to burn out.The present invention simultaneously will compare port voltage by electric capacity and carry out filtering, so the present invention has realized comparing the multiplexing of port.
The accompanying drawing explanation
Fig. 1 is the part block diagram of the fixed frequency switching mode LED Drive and Control Circuit that does not adopt open-circuit-protection for traditional.
Fig. 2 is the specific embodiment of Fig. 1.
Fig. 3 is the oscillogram of LED Drive and Control Circuit shown in Figure 1.
Fig. 4 is the part block diagram of the fixed frequency switching mode LED Drive and Control Circuit of the employing open-circuit-protection that proposes of the present invention.
Fig. 5 is a kind of LED drive circuit topological structure of the LED Drive and Control Circuit that proposes of the present invention.
Fig. 6 is another LED drive circuit topological structure of the LED Drive and Control Circuit that proposes of the present invention.
Fig. 7 is the oscillogram of the LED Drive and Control Circuit that proposes of the present invention.
Embodiment
Below in conjunction with block diagram of the present invention and specific embodiment schematic diagram content of the present invention, be elaborated.
As shown in Figure 4, LED Drive and Control Circuit 21 comprises:
LED load sample port FB, switch port SW, comparison port COMP;
Error amplification module 22: described error amplification module 22 is by LED load sample port input LED load sampled voltage, and the same reference voltage of LED load sampled voltage compares and amplifies;
Current sample module 210: 210 of described current sample moulds are sampled to the electric current that flows through power tube in switch module 211, and the current sampling signal of output offers comparison module 23 and current limliting module 27;
Comparison module 23, the current sampling signal of voltage and current sample module 210 outputs of 23 couples of comparison port COMP of described comparison module compares, and comparative result offers logic processing module 24;
Open circuit detects protection module 25 and comprises open circuit detection module 252 and open-circuit-protection module 251, the first input end input clock signal of described open circuit detection module (252), the control signal of the power tube of the second input input switch module 211, whether detect the LED load opens a way, and the duration of open circuit, the output open circuit status signal, surpass Preset Time when the duration of open circuit, and the open-circuit condition signal of output is effective;
Open-circuit-protection module 251, described open-circuit-protection module receives the open-circuit condition signal, the first output output of open-circuit-protection module 251 with the output acting in conjunction of error amplification module 22 in port COMP relatively, control ratio is than the voltage of port COMP, and the second output of open-circuit-protection module 251 is exported a current limit threshold;
Current limliting module 27, the current limit threshold of described current limliting module 27 open-circuit protection module 251 outputs and the current sampling signal of current sample module 210 outputs compare, and comparative result offers logic processing module 24;
Logic processing module 24, described logic processing module 24 output signal, the open circuit detection module of input clock signal, current limliting module 27 is respectively exported 25 open-circuit condition signal, the output signal of comparison module 23, and above-mentioned input is carried out to logical process, the output of logic processing module 24 offers driver module 28:
After LED drive circuit powers on, clocking, the second input of the open circuit detection module 252 of LED Drive and Control Circuit detects the control signal of the power tube of switch module 211, and current limliting module 27 is output as zero;
When the duration of LED load open circuit, be less than Preset Time, the LED Drive and Control Circuit is by comparing port COMP to capacitor charging, described electric capacity is connected between comparison port and ground, relatively port voltage continues to rise, second output output the first level of open-circuit-protection module 251, power tube control end signal is effective, and current sampling signal is zero, the open-circuit condition invalidating signal of open circuit detection module 252 outputs, the first output of open-circuit-protection module 251 does not act on comparing port COMP;
When the duration of LED load open circuit, surpass Preset Time, the open-circuit condition signal of open circuit detection module 252 outputs is effective, the first output that causes open-circuit-protection module 251 with the output acting in conjunction of error amplification module 22 in port COMP relatively, relatively port COMP lower voltage is zero, the second output of open-circuit-protection module 251 is reduced to second electrical level from the first level, the output signal of comparison module 23 is invalid, and logic processing module 24 only subject clock signal is controlled;
After the LED load is connected, the inductive current of LED drive circuit rises, current sample module 210 detects current sampling signal, current limit threshold and the current sampling signal of described current limliting module 27 open-circuit protection module 251 outputs compare, comparative result offers logic processing module 24, the output signal of logic processing module 24 resets, reset signal is turn-offed by driver module 28 power ratio control pipes, the open circuit detection module 252 detect the power tube control signal invalid after, the open-circuit condition invalidating signal of output, the first output of open-circuit-protection module 251 is not acting on comparison port COMP, second output output the first level of open-circuit-protection module 251, relatively port COMP voltage rises gradually from zero, after this by the set of clock signal control logic processing module, the power tube conducting, in comparison module 23 output signals when effective, control logic processing module 24 resets, power tube turn-offs.
The topology of the LED drive circuit that the LED Drive and Control Circuit is controlled as shown in Figure 5, comprises current sampling resistor RSENSE1, Schottky diode D1, inductance L 1, LED load.Input voltage VIN connects LED load anode through RSENSE1, LED load negative electrode connects inductance L 1 one ends, Schottky diode D1 is connected between the other end of input voltage VIN and inductance L 1, wherein inductance L 1 is connected the SW port of LED Drive and Control Circuit with Schottky diode D1, the FB port of LED load anodic bonding LED Drive and Control Circuit.
Further, described error amplification module 22 comprises operational amplifier A 1, the negative input end input internal reference voltage VREF of operational amplifier A 1, the FB port of the positive input termination LED drive circuit of operational amplifier A 1, the output of operational amplifier A 1 connects the COMP port.
Further, described comparison module 23 comprises comparator A2 and inverter A10, the positive input terminal input current sampled signal of comparator A2, the negative input termination COMP port of comparator A2.The input of the output termination inverter A10 of comparator A2, the output of inverter A10 is the output of module 23 as a comparison.
Further, described current limliting module 27 comprises comparator A3, the negative input termination current limit threshold of A3, the positive input terminal input current sampled signal of comparator A3.
Further, described logic processing module 24 comprises rest-set flip-flop A5, two input NOR gate A9, clock access rest-set flip-flop A5 set end, the rest-set flip-flop A5 first termination two input NOR gate A9 output that resets, the reset output of termination current limliting module 27 of rest-set flip-flop A5 second; Two input NOR gate A9 mono-end input termination 23 comparison module outputs, other end input pull-down status signal.
Further, described driver module 28 comprises driver A6, the output termination logic processing module output of driver A6, and the output signal of driver A6 directly enters switch module 211 driving N MOS switching tube M1.
Further, described switch module comprises NMOS pipe M1, and the M1 grid connects the output of driver A6, and the source electrode of NMOS pipe M1 is through resistance R 1 ground connection, and the drain electrode of NMOS pipe M1 is the SW port of LED Drive and Control Circuit;
Further, described open circuit detection module 252 comprises timer A7, the clock termination clock OSC of timer A7, the output of the driver connected A6 of input of timer A7.
Further, described open-circuit-protection module 251 comprises switch S 1, resistance R 2, and alternative selector A8, switch S 1 one terminating resistor R2, switch S 1 other end one end ground connection, switch S 1 is controlled the output of termination timer A7; The output of resistance R 2 one termination operational amplifier A 1, another termination switch S 1 of resistance R 2, the alternative selector A8 input high current limit threshold VCH of termination and low current limliting threshold value VCL, the alternative selector is controlled the output of termination timer A7, the negative input end of alternative selector A8 output termination current limliting modules A 3.
Described current sample module 210 comprises current sample amplifier A9, and current sample amplifier A9 input two ends connect respectively source electrode and the ground of NMOS pipe M1.
Figure 6 shows that the topology of another LED drive circuit that the LED Drive and Control Circuit is controlled,
The external LED drive circuit topology 20 of described LED drive circuit comprises inductance L 1, Schottky diode D1, current sampling resistor Rsense1 and LED load.Power supply VIN is connected to the SW port by the switch module of LED Drive and Control Circuit, the SW port to meet Schottky diode D1.The SW port connects LED load anode, and LED load negative electrode is connected to ground by current sampling resistor RSENSE1.LED load negative electrode is as the FB port of LED Drive and Control Circuit.
Switch module in Fig. 6 (11-2) comprises NMOS pipe M1, and the M1 grid of NMOS pipe connects the output of driver module A6, and the source electrode of NMOS pipe M1 connects the SW port of LED Drive and Control Circuit, and the drain electrode of NMOS pipe M1 meets power supply VIN through resistance R 1.
Fig. 7 is the waveform of the LED Drive and Control Circuit that proposes of the present invention; from shown in waveform can find; connecting moment; owing to adopting the present invention; the open circuit detection module has detected open-circuit condition; the voltage that the open-circuit-protection module will compare port COMP is made as no-voltage, and inductive current is rising after connection, until reach the setting current value.With comparison of wave shape shown in Fig. 3, find, the LED drive circuit of traditional LED drive control circuit, after inductive current after connection can rise to a very high value, then fall back to normal set point, when input voltage is higher, can be to LED Drive and Control Circuit or external LED load injury.
The connected mode of power tube and resistance in the switch module the present invention includes, the type of power tube, specific implementation in the open circuit detection module etc., those skilled in the art can be under the prerequisite without prejudice to its spirit, numerous embodiments can be arranged, or, by various compound mode, form different specific embodiments.
No matter above how detailed explanation is, can have in addition many modes to implement the present invention, and described in specification is specific embodiment of the present invention.All equivalent transformations that Spirit Essence is done according to the present invention or modification, within all should being encompassed in protection scope of the present invention.
The above-mentioned detailed description of the embodiment of the present invention be not exhaustive or be used to limit the present invention to above-mentioned clear and definite in form.Above-mentioned with schematic purpose explanation specific embodiment of the present invention and example in, those skilled in the art will recognize that and can carry out within the scope of the invention various equivalent modifications.
At above-mentioned declarative description specific embodiment of the present invention and the anticipated optimal set pattern has been described in, no matter how detailed explanation appearred hereinbefore, also can be implemented in numerous ways the present invention.The details of foregoing circuit structure and control mode thereof is carried out in details and can be carried out considerable variation at it, yet it still is included in the present invention disclosed herein.
Claims (3)
1. LED Drive and Control Circuit is characterized in that comprising:
LED load sample port, switch port (SW), comparison port (COMP);
The error amplification module: described error amplification module is by LED load sample port input LED load sampled voltage, and the same reference voltage of LED load sampled voltage compares and amplifies;
The current sample module, described current sample module is sampled to the electric current that flows through power tube in switch module, and the current sampling signal of output offers comparison module and current limliting module;
Comparison module, described comparison module compares the current sampling signal of the relatively voltage and current sample module output of port, and comparative result offers logic processing module;
Open circuit detects protection module, comprises open circuit detection module and open-circuit-protection module,
The control signal of the power tube of the second input input switch module of described open circuit detection module, detect the LED load and whether open a way, and the duration of open circuit, the output open circuit status signal, when the duration of open circuit, surpass Preset Time, described output open circuit status signal is effective;
The open-circuit-protection module, described open-circuit-protection module receives the open-circuit condition signal, the first output output of open-circuit-protection module is with the output acting in conjunction of error amplification module in port relatively, and control ratio is than the voltage of port, the second output output one current limit threshold of open-circuit-protection module;
The current limliting module, the current sampling signal of the current limit threshold of described current limliting module open-circuit protection module output and the output of current sample module compares, and comparative result offers logic processing module;
Logic processing module, described logic processing module is output signal, open a way the open-circuit condition signal of detection module output, the output signal of comparison module of input clock signal, current limliting module respectively, and above-mentioned input is carried out to logical process, the output of logic processing module offers driver module; Driver module, the power tube control end of described driver module driving switch module;
Switch module, the output connecting valve port of described switch module.
2. LED Drive and Control Circuit as claimed in claim 1, it is characterized in that the mode whether described open circuit detection module the second input detection LED load opens a way is: the control signal of the power tube of switch module is input to the second input, or directly inputs the detection signal at LED load two ends.
3. LED Drive and Control Circuit as claimed in claim 1 is characterized in that:
After LED drive circuit powers on, clocking, the second input of the open circuit detection module of LED Drive and Control Circuit detects the control signal of the power tube of switch module, and the current limliting module is output as zero;
When the duration of LED load open circuit, be less than Preset Time, the LED Drive and Control Circuit is by comparing port to capacitor charging, described electric capacity is connected between comparison port and ground, relatively port voltage continues to rise, second output output the first level of open-circuit-protection module, power tube control end signal is effective, and current sampling signal is zero, the open-circuit condition invalidating signal of open circuit detection module output, the first output of open-circuit-protection module does not act on comparing port;
When the duration of LED load open circuit, surpass Preset Time, the open-circuit condition signal of open circuit detection module output is effective, the first output that causes the open-circuit-protection module with the output acting in conjunction of error amplification module in port relatively, relatively port voltage is reduced to zero, the second output of open-circuit-protection module is reduced to second electrical level from the first level, the output signal of comparison module is invalid, and logic processing module only subject clock signal is controlled;
After the LED load is connected, the inductive current of LED drive circuit rises, the current sample module detects current sampling signal, current limit threshold and the current sampling signal of described current limliting module open-circuit protection module output compare, comparative result offers logic processing module, the output signal of logic processing module resets, reset signal is turn-offed by driver module power ratio control pipe, the open circuit detection module detect the power tube control signal invalid after, the open-circuit condition invalidating signal of output, the first output of open-circuit-protection module is not acting on the comparison port, second output output the first level of open-circuit-protection module, relatively port voltage rises gradually from zero, after this by the set of clock signal control logic processing module, the power tube conducting, when the comparison module output signal is effective, the control logic processing module resets, power tube turn-offs.
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CN102821520A (en) * | 2012-08-07 | 2012-12-12 | 广州晶锐信息技术有限公司 | LED (light-emitting diode) driving circuit and control method thereof |
CN103491666B (en) * | 2012-12-19 | 2015-07-29 | 深圳市安派电子有限公司 | A kind of flasher of power valve protective circuit |
CN103747558A (en) * | 2013-11-28 | 2014-04-23 | 成都岷创科技有限公司 | LED driving circuit based on time multiplier compensation technology |
CN103731954B (en) * | 2013-11-28 | 2015-07-15 | 成都岷创科技有限公司 | Time multiplying signal generating circuit |
US9480124B2 (en) | 2013-12-25 | 2016-10-25 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Single string over power protection and light source driver circuit used in display device |
CN103761943B (en) * | 2013-12-25 | 2016-07-06 | 深圳市华星光电技术有限公司 | List string overpower protection in a kind of display and light source driving circuit |
CN103826363B (en) * | 2014-01-28 | 2016-05-25 | 杰华特微电子(杭州)有限公司 | For the hot plug holding circuit of LED luminaire |
US9846665B2 (en) * | 2014-11-05 | 2017-12-19 | Stmicroelectronics Asia Pacific Pte Ltd | Chip synchronization by a master-slave circuit |
CN110335580B (en) * | 2019-08-19 | 2021-12-07 | 深圳南云微电子有限公司 | Average current type buzzer drive circuit |
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