WO2021175024A1 - 一种led调光电路、装置及其调光方法 - Google Patents

一种led调光电路、装置及其调光方法 Download PDF

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Publication number
WO2021175024A1
WO2021175024A1 PCT/CN2021/072360 CN2021072360W WO2021175024A1 WO 2021175024 A1 WO2021175024 A1 WO 2021175024A1 CN 2021072360 W CN2021072360 W CN 2021072360W WO 2021175024 A1 WO2021175024 A1 WO 2021175024A1
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Prior art keywords
switch
dimming
sampling resistor
constant current
current source
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PCT/CN2021/072360
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English (en)
French (fr)
Inventor
邓迅升
陈博
麦炎全
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深圳市晟碟半导体有限公司
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Publication of WO2021175024A1 publication Critical patent/WO2021175024A1/zh

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current

Definitions

  • the present invention relates to the field of LED technology, in particular to an LED dimming circuit, device and dimming method.
  • LED lights usually have two dimming methods.
  • One is the PWM dimming method, which adjusts the brightness of the LED light string by controlling the ratio of the turn-on and turn-off time of the LED light string.
  • the advantage of using this method is that the circuit structure is simple and The brightness of the LED light string can be adjusted to a very low level, but because of its continuous turning on and off of the LED light string current, the sudden change of the light string current leads to serious conduction radiation problems; the other is to use DIM dimming method, by controlling DIM dimming The size of the light voltage, and then change the current of the LED light string to achieve the brightness change, the advantage of using this method is that there is no conduction radiation problem, but it uses a constant current source to achieve the current adjustment of the LED light string, and the minimum current of the LED light string is affected by The offset voltage of the operational amplifier in the constant current source is limited.
  • the LED string current is not controlled by the dimming voltage, and because the offset voltage of the operational amplifier of each LED driver chip has deviations, it is used.
  • the dimming method of the LED string current cannot be adjusted too small, the brightness cannot be adjusted too low, the dimming depth is poor, and the offset voltage difference of the operational amplifier between the chips causes the LED lights to be consistent when the brightness is reduced. Poor sex.
  • the purpose of the present invention is to provide an LED dimming circuit, device and dimming method, which can effectively solve the problem of poor dimming depth in the existing dimming method.
  • An LED dimming circuit includes a control module, a digital-to-analog conversion module, an LED light string, and a constant current source module.
  • the constant current source module includes a first sampling resistor and/or a second sampling resistor; the control module is used for After comparing the input dimming data with the first preset value, the constant current source module is controlled to select the first sampling resistor or the second sampling resistor according to the comparison result, and select to output the first brightness data or the second sampling resistor.
  • the digital-to-analog conversion module is configured to output a corresponding dimming signal to the constant current source module according to the first brightness data or the second brightness data;
  • the current source module is used for controlling the working current flowing through the LED light string according to the dimming signal.
  • the constant current source module further includes a selection unit and a constant current source unit; the selection unit selects the first sampling resistor according to the first control signal, and according to the second control signal The signal selects the second sampling resistor; the constant current source unit controls the working current flowing through the LED light string according to the dimming signal.
  • the selection unit includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, a sixth switch, and an inverter;
  • the constant current source unit includes a first switch, a second switch, a third switch, and an inverter.
  • One end of the first switch and one end of the second switch are both connected to the inverting input end of the first operational amplifier, the control end of the first switch is connected to the control module, and the other end of the first switch is One end is connected to the source of the first MOS transistor and one end of the first sampling resistor; the control end of the second switch, the control end of the fourth switch and the control end of the fifth switch are all connected to the The output terminal of the inverter, the other end of the second switch is connected to the source of the second MOS tube and one end of the second sampling resistor; the other end of the first sampling resistor is connected to the second The other ends of the sampling resistors are all grounded; one end of the third switch and one end of the fourth switch are both connected to the output end of the first operational amplifier, and the other end of the third switch and the fifth switch One end is connected to the gate of the first MOS transistor, the other end of the fourth switch and one end of the sixth switch are both connected to the gate of the second MOS transistor, and the other end of the fifth switch
  • the other end of the sixth switch is grounded, the control end of the third switch and the control end of the sixth switch are both connected to the control module; the non-inverting input end of the first operational amplifier is connected to the digital Analog conversion module; the drain of the first MOS tube and the drain of the second MOS tube are both connected to the negative electrode of the LED string, and the input terminal of the inverter is connected to the control module.
  • the selection unit includes a seventh switch, an eighth switch, and an inverter;
  • the constant current source unit includes a second operational amplifier and a third MOS tube;
  • the seventh switch controls The terminal and the input terminal of the inverter are connected to the control module, and one end of the seventh switch and one end of the eighth switch are connected to the inverting input terminal of the second operational amplifier and the third MOS transistor.
  • the other end of the seventh switch is grounded through the first sampling resistor, the other end of the eighth switch is grounded through the second sampling resistor, and the drain of the third MOS transistor is connected to the The negative electrode of the LED light string, the positive input end of the second operational amplifier is connected to the digital-to-analog conversion module, the output end of the second operational amplifier is connected to the gate of the third MOS tube, and the inverter The output terminal of is connected to the control terminal of the eighth switch.
  • the selection unit includes a ninth switch, a tenth switch and an inverter;
  • the constant current source unit includes a third operational amplifier, a fourth operational amplifier, a fourth MOS tube, and a fifth MOS tube;
  • the non-inverting input terminal of the third operational amplifier and the non-inverting input terminal of the fourth operational amplifier are connected to the digital-to-analog conversion module, one end of the ninth switch and the output of the third operational amplifier Terminals are connected to the gate of the fourth MOS transistor, the inverting input terminal of the third operational amplifier and the source of the fourth MOS transistor are connected to ground through the first sampling resistor;
  • the ninth switch The control terminal is connected to the output terminal of the inverter, the control terminal of the tenth switch and the input terminal of the inverter are both connected to the control module; one end of the tenth switch and the fourth operational amplifier The output ends of the fifth MOS transistor are all connected to the gate of the fifth MOS transistor, the other end of the tenth switch is grounded, and the
  • the digital-to-analog conversion module includes a voltage divider unit, a decoding unit, and a multiple selection unit; the voltage divider unit divides the reference voltage and outputs corresponding amplitude values through different taps.
  • the dimming signal is sent to the multiple selection unit; the decoding unit controls the multiple selection unit according to the first brightness data or the second brightness data to output all the taps corresponding to the voltage divider unit.
  • the dimming signal is output to the constant current source module.
  • a dimming method based on the above-mentioned LED dimming circuit includes the following steps:
  • control module After the control module compares the input dimming data with a first preset value, it controls the constant current source module to select the first sampling resistor or the second sampling resistor according to the comparison result, and selects to output the first sampling resistor. Brightness data or second brightness data to the digital-to-analog conversion module;
  • the digital-to-analog conversion module outputs a corresponding dimming signal to the constant current source module according to the first brightness data or the second brightness data;
  • the constant current source module controls the working current flowing through the LED light string according to the dimming signal.
  • the control module compares the input dimming data with a first preset value, and then controls the constant current source module to select the first sampling resistor or the first sampling resistor according to the comparison result.
  • the step of selecting the second sampling resistor and outputting the first brightness data or the second brightness data to the digital-to-analog conversion module includes:
  • the control module compares when the dimming data is greater than or equal to the first preset value, and outputs a first control signal to the constant current source module to control it to select the first sampling resistor and select the output
  • the first brightness data corresponding to the dimming data is sent to the digital-to-analog conversion module; when the dimming data is less than the first preset value, a second control signal is output to the constant current source module to control its selection
  • the second sampling resistor after multiplying the dimming data by a second preset value, select and output the corresponding second brightness data after the dimming data is multiplied by the second preset value to the digital analog Conversion module.
  • An LED dimming device includes a housing, a PCB board is arranged in the housing, and the above-mentioned LED dimming circuit is arranged on the PCB board.
  • the LED dimming circuit includes a control module, a digital-to-analog conversion module, an LED light string, and a constant current source module.
  • the current source module includes a first sampling resistor and/or a second sampling resistor; the control module is used to compare the input dimming data with a first preset value, and then control the constant current source module to select the desired value according to the comparison result.
  • the first sampling resistor or the second sampling resistor and select to output the first brightness data or the second brightness data to the digital-to-analog conversion module; the digital-to-analog conversion module is used for according to the first brightness data or the The second brightness data outputs a corresponding dimming signal to the constant current source module; the constant current source module is used to control the working current flowing through the LED string according to the dimming signal; the present invention can effectively solve the problem The problem of poor dimming depth in existing dimming methods.
  • Figure 1 is a structural block diagram of the LED dimming circuit provided by the present invention.
  • FIG. 2 is a circuit schematic diagram of the constant current source module in the first embodiment of the LED dimming circuit provided by the present invention
  • Fig. 3 is a circuit schematic diagram of a control module in the LED dimming circuit provided by the present invention.
  • Figure 4 is a schematic circuit diagram of the digital-to-analog conversion module in the LED dimming circuit provided by the present invention
  • 5 is a timing diagram of the first preset value, dimming data, dimming signal, control signal, and sampling resistor of the LED dimming circuit provided by the present invention
  • FIG. 6 is a circuit schematic diagram of the constant current source module in the second embodiment of the LED dimming circuit provided by the present invention.
  • FIG. 7 is a circuit diagram of the constant current source module in the third embodiment of the LED dimming circuit provided by the present invention.
  • FIG. 8 is a flow chart of the steps of the driving method of the LED dimming circuit provided by the present invention.
  • the LED dimming circuit, device and dimming method provided by the present invention can effectively solve the problem of poor dimming depth in the existing dimming method.
  • the LED dimming circuit provided by the present invention includes a control module 100, a digital-to-analog conversion module 200, an LED light string 300, and a constant current source module 400.
  • the control module 100 is connected to dimming data
  • the negative pole of the LED light string 300 is connected to the power input terminal.
  • the constant current source module 400 includes a first sampling resistor Rcs1 and/or a second sampling resistor Rcs2; the control module 100 is used to compare the input dimming data with a first preset value, and then according to the comparison result Controlling the constant current source module 400 to select the first sampling resistor Rcs1 and/or the second sampling resistor Rcs2, and select to output the first brightness data or the second brightness data to the digital-to-analog conversion module 200;
  • the digital-to-analog conversion module 200 is configured to output a corresponding dimming signal to the constant current source module 400 according to the first brightness data or the second brightness data; the constant current source module 400 controls according to the dimming signal The operating current flowing through the LED light string 300.
  • the present invention compares the dimming data with the first preset value, according to the size of the dimming data, selects and outputs different brightness data and the sampling resistor corresponding to the brightness data, and then outputs the corresponding brightness data
  • the dimming signal adjusts the working current of the LED light string 300 to ensure that the corresponding relationship between the dimming data and the working current of the LED light string 300 remains unchanged, effectively avoiding the offset voltage of the constant current source module 400
  • the influence of light depth; the dimming data can be the data received by the wireless receiver, the data obtained by counting the PWM dimming signal, the data received through the data bus, and the data sampled by ADC (Analog-to-Digital converter), etc. .
  • the control module 100 of the present invention includes a comparator 110, a multiplier 130, and a selector 120.
  • the non-inverting input terminal of the comparator 110 is connected to the dimming data input terminal.
  • the inverting input terminal of 110 is connected to the first preset value input terminal, the output terminal of the comparator 110 is connected to the selector 120 and the constant current source module 400; the input terminal of the multiplier 130 is connected to dimming data
  • the input terminal and the second preset value input terminal, the output terminal of the multiplier 130 is connected to the selector 120, and the selector 120 is also connected to the digital-to-analog conversion module 200.
  • the comparator 110 is used to compare when the dimming data is greater than or equal to the first preset value, output a first control signal to the constant current source module 400, and when the dimming data is less than When the first preset value is used, a second control signal is output to the constant current source module 400;
  • the multiplier 130 is configured to multiply the dimming data by the second preset value and output to the The selector 120;
  • the selector 120 is configured to select and output the first brightness data corresponding to the dimming data to the digital-to-analog conversion when the dimming data is greater than or equal to the first preset value Module 200, when the dimming data is less than the first preset value, select the corresponding second brightness data after the dimming data is multiplied by the second preset value to the digital-to-analog conversion module 200.
  • the offset voltage of the constant current source module 400 refers to the offset voltage of the corresponding operational amplifier in the constant current source module 400, and the first preset value is a preset comparison reference value. Is determined by the offset voltage of the corresponding operational amplifier. When the dimming data becomes smaller, the dimming signal becomes smaller accordingly. When the dimming signal is close to or less than the offset voltage of the operational amplifier, the output of the operational amplifier is not controlled, and the working current flowing through the LED light string 300 is not affected. Control, the LED light string 300 flickers, and the dimming depth (the working current of the LED light string 300 cannot be adjusted to a very low level) is affected by the offset voltage of the operational amplifier.
  • the dimming signal corresponding to the first preset value should be greater than the offset voltage of the operational amplifier, and when the dimming data is less than the first preset value, the dimming signal and the constant current source module are amplified in the same proportion
  • the resistance value of the sampling resistor in 400 that is, the dimming data and the resistance value of the sampling resistor are simultaneously amplified by the multiple set by the second preset value, that is, when the dimming data is less than the first preset value
  • the control module 100 controls the constant current source module 400 to select the second sampling resistor Rcs2, and selects the dimming data multiplied by the second preset value and the corresponding second brightness data to the
  • the digital-to-analog conversion module 200 ensures that the corresponding relationship between the dimming data and the current of the LED light string 300 remains unchanged, so that the dimming signal is expanded by a multiple of the second preset value that is far greater than the offset voltage of the operational amplifier, and the output of the operational amplifier Controllable, the
  • the first control signal is a high-level control signal
  • the second control signal is a low-level control signal
  • the comparator 110 receives the dimming data, it compares with the first preset value.
  • the dimming data is greater than or equal to the first preset value
  • output a high-level control signal to the constant current source module 400, so that the constant current source module 400 selects the first sampling resistor Rcs1
  • the dimming data is output as brightness data, that is, the first brightness data is output to the digital-to-analog conversion module 200
  • a low-level control signal is output to the
  • the constant current source module 400 enables the constant current source module 400 to select the first sampling resistor Rcs1, and at the same time output the dimming data * the second preset value as brightness data, that is, output second brightness data To the digital-to-analog conversion module 200, and the size of the dimming signal output by the digital-to
  • the constant current source module 400 further includes a selection unit 410 and a constant current source unit 420, the selection unit 410 is connected to the output terminal of the comparator 110, and the constant current source unit 420 Connected to the digital-to-analog conversion module 200, one end of the first sampling resistor Rcs1 and one end of the second sampling resistor Rcs2 are both connected to the selection unit 410 and the constant current source unit 420, the first sampling resistor The other end of Rcs1 and the other end of the second sampling resistor Rcs2 are both grounded.
  • the selection unit 410 selects the first sampling resistor Rcs1 according to the first control signal, and selects the second sampling resistor Rcs2 according to the second control signal; the constant current source unit 420 selects the second sampling resistor Rcs2 according to the dimming signal To control the working current flowing through the LED light string 300, the selection unit 410 selects the first sampling resistor Rcs1 or the second sampling resistor Rcs2 to connect to the circuit according to the control signal output by the comparator 110; When the dimming data is greater than or equal to the first preset value, the comparator 110 outputs a first control signal to the selection unit 410, and the selection unit 410 selects the first sampling resistor Rcs1 to access, The corresponding digital-to-analog conversion module 200 also sends the dimming signal output according to the first brightness data to the constant current source unit 420; when the dimming data is less than the first preset value, the comparison The device 110 outputs a second control signal to the selection unit 410, and the selection unit
  • the light signal is sent to the constant current source unit 420, so that the control module 100 controls the constant current source module 400 to select sampling resistors with different resistance values, and obtains the dimming signal corresponding to the brightness data, so as to ensure the adjustment.
  • the corresponding relationship between the optical data and the operating current of the LED light string 300 remains unchanged.
  • the selection unit 410 includes a first switch Key1, a second switch Key2, a third switch Key3, a fourth switch Key4, a fifth switch Key5, and a sixth switch.
  • the constant current source unit 420 includes a first operational amplifier OP1, a first MOS transistor Q1 and a second MOS transistor Q2; one end of the first switch Key1 and the second switch Key2 One end is connected to the inverting input end of the first operational amplifier OP1, the control end of the first switch Key1 is connected to the output end of the comparator 110, and the other end of the first switch Key1 is connected to the first MOS
  • the source of the tube Q1 and one end of the first sampling resistor Rcs1; the control end of the second switch Key2, the control end of the fourth switch Key4, and the control end of the fifth switch Key5 are all connected to the inverter
  • the output terminal of the inverter INV, the other end of the second switch Key2 is connected to
  • the comparator 110 When the comparator 110 outputs a high-level control signal, the first switch Key1, the third switch Key3, and the sixth switch Key6 are turned on, so The second switch Key2, the fourth switch Key4, and the fifth switch Key5 are turned off, and the first sampling resistor Rcs1 is connected to the circuit, so that the constant current source module 400 is powered by the first operational amplifier OP1, The first MOS transistor Q1 and the first sampling resistor Rcs1 are jointly formed to adjust the working current flowing through the LED light string 300; when the comparator 110 outputs a low-level control signal, the first The switch Key1, the third switch Key3, and the sixth switch Key6 are turned off, the second switch Key2, the fourth switch Key4, and the fifth switch Key5 are turned on, and the second sampling resistor Rcs2 is connected Input circuit, so that the constant current source module 400 is composed of the first operational amplifier OP1, the second MOS transistor Q2, and the second sampling resistor Rcs2 to control the operation of the LED light string 300 Current, where
  • the sampling resistor in the constant current source module 400 is the first sampling resistor Rcs1, and the dimming signal output by the digital-to-analog conversion module 200 corresponds to the dimming signal.
  • the working current flowing through the LED light string 300 dimming signal/Rcs1; when the comparator 110 outputs a low-level control signal, the sampling resistor in the constant current source module 400 is the second sampling Resistor Rcs2.
  • the dimming signal output by the digital-to-analog conversion module 200 corresponds to the dimming data*the second preset value
  • the working current flowing through the LED light string 300 dimming signal/Rcs2, where Rcs2 is the resistance value of the second sampling resistor Rcs2, and Rcs1 is the resistance value of the first sampling resistor Rcs1;
  • the dimming signal voltage is amplified, which reduces the influence of the offset voltage of the operational amplifier on the dimming depth.
  • the digital-to-analog conversion module 200 includes a voltage dividing unit 210, a decoding unit 220, and a multiple selection unit 230; the voltage dividing unit 210 divides the reference voltage and outputs it through different taps.
  • the dimming signal corresponding to the amplitude is sent to the multiple selection unit 230; the decoding unit 220 controls the multiple selection unit 230 according to the first brightness data or the second brightness data to divide the
  • the dimming signal output by the voltage unit 210 corresponding to the tap is output to the constant current source module 400, and the digital-to-analog conversion module 200 provides the constant current source module 400 with a dimming signal, thereby realizing the adjustment of the working current .
  • the voltage dividing unit 210 includes a resistor string, and the resistor string is composed of several voltage dividing resistors in series.
  • the specific number of voltage dividing resistors can be selected according to actual dimming requirements, which is not limited by the present invention.
  • the upper end of the resistor string is connected to the reference voltage output terminal Vref, and the lower end of the resistor string is grounded; in this embodiment, the number of voltage dividing resistors is 1024, which are R0, R1, R2,..., R1021, R1022, and R1023,
  • the resistance value of each resistor is equal; the multiple selection unit 230 includes a number of control switches corresponding to the voltage divider resistance, as shown in K0 to K1023 in FIG.
  • each control switch is connected to the constant current source module 400, and the control end of each control switch is connected to the decoding unit 220, and the control switch can be realized by a relay, a transistor, a MOSFET, a transmission gate, and the like.
  • the decoding unit 220 After the decoding unit 220 receives the first brightness data or the second brightness data output by the selector 120, it controls the corresponding control switch to be turned on or off, and then selects the corresponding dimming signal to output to the constant current source In unit 420, the control terminal of the control switch is turned on when it is at a high level, and turned off when it is at a low level; the decoding unit 220 uses one-hot encoding to combine the received first brightness data and the second brightness After the data is converted into one-hot codes (S0 ⁇ S1023), the respective corresponding control switches are strobed, and then the dimming signal corresponding to the resistor string is selected and output to the constant current source unit 420.
  • the bit width of the brightness data is 10 bits. After one-hot encoding, 1024 control signals, namely one-hot codes S0 to S1023, are output, and only one control signal is high at the same time.
  • the first preset value and the second preset value are both 32.
  • the first preset value and the second preset value may also be different.
  • the optical data bit width is 10bit, 1024-level dimming, and the reference voltage Vref is 3.3V.
  • the comparator 110 When the dimming data changes from large to small and is not less than the first preset value, the comparator 110 outputs a high-level control signal, and the constant current source module 400 selects the resistance of the sampling resistor to be R, corresponding to all
  • the dimming signal When the dimming data is equal to the preset value 1, the dimming signal can be calculated to be 103mV.
  • the offset voltage is generally below tens of millivolts;
  • the string current calculation method is the same, that is, the sampling resistance and dimming data are both amplified by 32 times the second preset value, while ensuring that the corresponding relationship
  • the selection unit 410 includes a seventh switch Key7, an eighth switch Key8, and an inverter INV;
  • the constant current source unit 420 includes a second operational amplifier OP2 and the third MOS transistor Q3;
  • the control end of the seventh switch Key7 and the input end of the inverter INV are connected to the control module 100, one end of the seventh switch Key7 and the eighth switch Key8 One end is connected to the inverting input end of the second operational amplifier OP2 and the source of the third MOS transistor Q3, the other end of the seventh switch Key7 is grounded through the first sampling resistor Rcs1, and the eighth switch
  • the other end of Key8 is grounded through the second sampling resistor Rcs2,
  • the drain of the third MOS transistor Q3 is connected to the negative electrode of the LED light string 300, and the positive input end of the second operational amplifier OP2 is connected to the digital In the analog conversion module 200, the output terminal of the second operational amplifier OP2 is connected to the gate of the third MOS transistor Q3,
  • the seventh switch Key7 is turned on, the eighth switch Key8 is turned off, and the first sampling resistor Rcs1 is connected to the circuit, so that all
  • the constant current source module 400 is composed of the second operational amplifier OP2, the third MOS transistor Q3, and the first sampling resistor Rcs1.
  • the dimming signal corresponds to dimming data, which flows through the LED light string 300.
  • the selection unit 410 includes a ninth switch Key9, a tenth switch Key10, and an inverter INV;
  • the constant current source unit 420 includes a third operational amplifier OP3, the fourth operational amplifier OP4, the fourth MOS transistor Q4, and the fifth MOS transistor Q5;
  • the non-inverting input terminal of the third operational amplifier OP3 and the non-inverting input terminal of the fourth operational amplifier OP4 are connected to the digital-to-analog
  • one end of the ninth switch Key9 and the output end of the third operational amplifier OP3 are both connected to the gate of the fourth MOS transistor Q4, and the inverting input end of the third operational amplifier OP3 is connected to the
  • the source of the fourth MOS transistor Q4 is connected to the ground through the first sampling resistor Rcs1;
  • the control terminal of the ninth switch Key9 is connected to the output terminal of the inverter INV, and the control terminal of the tenth switch Key10 is connected to the
  • the source of the fourth MOS transistor Q4 is
  • the other end of the tenth switch Key10 is grounded, the inverting input end of the fourth operational amplifier OP4 and the source of the fifth MOS transistor Q5 are both grounded through the second sampling resistor Rcs2, and the first The drain of the four MOS transistor Q4 and the drain of the fifth MOS transistor Q5 are both connected to the negative electrode of the LED light string 300.
  • the ninth switch Key9 when the comparator 110 outputs a high-level control signal, the ninth switch Key9 is turned off, the tenth switch Key10 is turned on, and the gate of the fifth MOS transistor Q5 passes through the The tenth switch Key10 is connected to the ground, the fifth MOS transistor Q5 is not turned on, and the first sampling resistor Rcs1 is connected to the circuit, so that the constant current source module 400 is connected to the third operational amplifier OP3 and the fourth operational amplifier OP3.
  • the MOS tube Q4 and the first sampling resistor Rcs1 are jointly composed.
  • the dimming signal corresponds to dimming data.
  • the working current flowing through the LED light string 300 dimming signal/Rcs1; when the comparator 110 outputs a low level
  • the ninth switch Key9 is turned on, the tenth switch Key10 is turned off, the gate of the fourth MOS transistor Q4 is connected to the ground through the ninth switch Key9, and the fourth MOS transistor Q4 is not Turned on, the second sampling resistor Rcs2 is connected to the circuit, so that the constant current source module 400 is composed of the fourth operational amplifier OP4, the fifth MOS transistor Q5, and the second sampling resistor Rcs2.
  • the dimming signal output by the digital-to-analog conversion module 200 corresponds to the dimming data*the second preset value
  • the dimming signal is amplified by the second preset value
  • Rcs2 Rcs1*the second preset value
  • Working current dimming signal/Rcs2.
  • the present invention also provides a corresponding LED dimming circuit dimming method, which specifically includes the following steps:
  • the control module controls the constant current source module to select the first sampling resistor and/or the second sampling resistor according to the comparison result, and Select and output the first brightness data or the second brightness data to the digital-to-analog conversion module;
  • the digital-to-analog conversion module is configured to output a corresponding dimming signal to the constant current source module according to the first brightness data or the second brightness data;
  • the constant current source module is configured to control the working current flowing through the LED light string according to the dimming signal.
  • step S100 specifically includes: the control module compares that when the dimming data is greater than or equal to the first preset value, outputting a first control signal to the constant current source module to control it to select the first A sampling resistor, and select and output the first brightness data corresponding to the dimming data to the digital-to-analog conversion module; when the dimming data is less than the first preset value, output a second control signal to the
  • the constant current source module controls it to select the second sampling resistor, and after multiplying the dimming data by a second preset value, select and output the first corresponding to the dimming data multiplied by the second preset value. Two brightness data to the digital-to-analog conversion module.
  • the present invention also correspondingly provides an LED dimming device, including a housing, a PCB board is arranged in the housing, and the above-mentioned LED dimming circuit is arranged on the PCB board.
  • an LED dimming device including a housing, a PCB board is arranged in the housing, and the above-mentioned LED dimming circuit is arranged on the PCB board.
  • the LED dimming circuit includes a control module, a digital-to-analog conversion module, an LED light string, and a constant current source module.
  • the module includes a first sampling resistor or a second sampling resistor; the control module is used to compare the input dimming data with a first preset value, and then control the constant current source module to select the first sampling according to the comparison result Resistor and/or the second sampling resistor, and select to output the first brightness data or the second brightness data to the digital-to-analog conversion module; the digital-to-analog conversion module is used for the first brightness data or the first brightness data Two brightness data output the corresponding dimming signal to the constant current source module; the constant current source module is used to control the working current flowing through the LED string according to the dimming signal; the present invention can effectively solve the existing problem The problem of poor dimming depth in different dimming methods.

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Abstract

本发明公开了一种LED调光电路、装置及其调光方法，所述LED调光电路包括控制模块、数模转换模块、LED灯串和恒流源模块，所述恒流源模块包括第一采样电阻和/或第二采样电阻；所述控制模块将调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；所述数模转换模块根据第一亮度数据或第二亮度数据输出对应的调光信号至所述恒流源模块；所述恒流源模块根据所述调光信号控制流经LED灯串的工作电流；本发明能够有效减小了运算放大器失调电压对调光深度的影响。

Description

一种LED调光电路、装置及其调光方法 技术领域
本发明涉及LED技术领域，特别涉及一种LED调光电路、装置及其调光方法。
背景技术
LED灯通常有两种调光方式，一种是采用PWM调光方式，通过控制LED灯串的导通和关断时间比例来调整LED灯串的亮度，使用该方式的好处是电路结构简单并且LED灯串亮度可以调到很低，但是因为其不停的开、关LED灯串电流，灯串电流的突变导致其传导辐射问题严重；另一种是采用DIM调光方式，通过控制DIM调光电压的大小，继而改变LED灯串的电流来实现亮度的变化，使用该方式的好处是无传导辐射问题，但是其通过恒流源来实现LED灯串的电流调节，LED灯串最小电流受恒流源中运算放大器的失调电压限制，当调光电压等于或小于失调电压时，LED灯串电流不受调光电压控制，并且因为各个LED驱动芯片运算放大器的失调电压有偏差，导致使用这种调光方式的LED灯串电流不能调的太小，亮度不能调的太低，调光深度差，并且各芯片间运算放大器的失调电压差异导致各个LED灯之间在亮度调低时的一致性差。
因而现有技术还有待改进和提高。
发明内容
鉴于上述现有技术的不足之处，本发明的目的在于提供一种LED调光电路、装置及其调光方法，能够有效解决现有的调光方式中调光深度差的问题。
为了达到上述目的，本发明采取了以下技术方案：
一种LED调光电路，包括控制模块、数模转换模块、LED灯串和恒流源模块，所述恒流源模块包括第一采样电阻和/或第二采样电阻；所述控制模块用于将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块； 所述数模转换模块用于根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；所述恒流源模块用于根据所述调光信号控制流经所述LED灯串的工作电流。
所述的LED调光电路中，所述控制模块具体用于比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块控制其选择所述第一采样电阻，并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块控制其选择所述第二采样电阻，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块；所述第二采样电阻的阻值＝所述第一采样电阻的阻值*第二预设值。
所述的LED调光电路中，所述恒流源模块还包括选择单元和恒流源单元；所述选择单元根据所述第一控制信号选择所述第一采样电阻，根据所述第二控制信号选择所述第二采样电阻；所述恒流源单元根据所述调光信号控制流经所述LED灯串的工作电流。
所述的LED调光电路中，所述选择单元包括第一开关、第二开关、第三开关、第四开关、第五开关、第六开关、反相器；所述恒流源单元包括第一运算放大器、第一MOS管和第二MOS管；
所述第一开关的一端和所述第二开关的一端均连接所述第一运算放大器的反相输入端，所述第一开关的控制端连接所述控制模块，所述第一开关的另一端连接所述第一MOS管的源极和所述第一采样电阻的一端；所述第二开关的控制端、所述第四开关的控制端和所述第五开关的控制端均连接所述反相器的输出端，所述第二开关的另一端连接所述第二MOS管的源极和所述第二采样电阻的一端；所述第一采样电阻的另一端和所述第二采样电阻的另一端均接地；所述第三开关的一端和所述第四开关的一端均连接所述第一运算放大器的输出端，所述第三开关的另一端和所述第五开关的一端均连接所述第一MOS管的栅极，所述第四开关的另一端和所述第六开关的一端均连接所述第二MOS管的栅极，所述第五开关的另一端和所述第六开关的另一端均接地，所述第三开关的控制端和所述第六开关的控制端均连接所述控制模块；所述第一运算放大器的正相 输入端连接所述数模转换模块；所述第一MOS管的漏极和所述第二MOS管的漏极均连接所述LED灯串的负极，所述反相器的输入端连接所述控制模块。
所述的LED调光电路中，所述选择单元包括第七开关、第八开关和反相器；所述恒流源单元包括第二运算放大器和第三MOS管；所述第七开关的控制端和所述反相器的输入端连接所述控制模块，所述第七开关的一端和所述第八开关的一端连接所述第二运算放大器的反相输入端和所述第三MOS管的源极，所述第七开关的另一端通过所述第一采样电阻接地，所述第八开关的另一端通过所述第二采样电阻接地，所述第三MOS管的漏极连接所述LED灯串的负极，所述第二运算放大器的正向输入端连接所述数模转换模块，所述第二运算放大器的输出端连接所述第三MOS管的栅极，所述反相器的输出端连接所述第八开关的控制端。
所述的LED调光电路中，所述选择单元包括第九开关、第十开关和反相器；所述恒流源单元包括第三运算放大器、第四运算放大器、第四MOS管和第五MOS管；所述第三运算放大器的正相输入端和所述第四运算放大器的正相输入端连接所述数模转换模块，所述第九开关的一端和所述第三运算放大器的输出端均连接所述第四MOS管的栅极，所述第三运算放大器的反相输入端和所述第四MOS管的源极连接通过所述第一采样电阻接地；所述第九开关的控制端连接所述反相器的输出端，所述第十开关的控制端和所述反相器的输入端均连接所述控制模块；所述第十开关的一端和所述第四运算放大器的输出端均连接所述第五MOS管的栅极，所述第十开关的另一端接地，所述第四运算放大器的反相输入端和所述第五MOS管的源极均通过所述第二采样电阻接地，所述第四MOS管的漏极和所述第五MOS管的漏极均连接所述LED灯串的负极。
所述的LED调光电路中，所述数模转换模块包括分压单元、译码单元和多路选择单元；所述分压单元对参考电压进行分压后通过不同的抽头输出对应幅值的所述调光信号至所述多路选择单元；所述译码单元根据所述第一亮度数据或所述第二亮度数据控制所述多路选择单元将所述分压单元对应抽头输出的所述调光信号输出至所述恒流源模块。
一种基于如上所述的LED调光电路的调光方法，包括如下步骤：
所述控制模块将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；
所述数模转换模块根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；
所述恒流源模块根据所述调光信号控制流经所述LED灯串的工作电流。
所述LED调光电路的调光方法中，所述控制模块将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块的步骤包括：
所述控制模块比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块控制其选择所述第一采样电阻，并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块控制其选择所述第二采样电阻，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块。
一种LED调光装置，包括外壳，所述外壳内设置有PCB板，所述PCB板上设置有如上所述的LED调光电路。
相较于现有技术，本发明提供的LED调光电路、装置及其调光方法，所述LED调光电路包括控制模块、数模转换模块、LED灯串和恒流源模块，所述恒流源模块包括第一采样电阻和/或第二采样电阻；所述控制模块用于将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；所述数模转换模块用于根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；所述恒流源模块用于根据所述调光信号控制流经所述LED灯串的工作电流；本发明能够有效解决现有的调光方式中调光深度差的问题。
附图说明
图1为本发明提供的LED调光电路的结构框图；
图2为本发明提供的LED调光电路第一实施例中恒流源模块的电路原理图；
图3为本发明提供的LED调光电路中控制模块的电路原理图；
图4为本发明提供的LED调光电路中数模转换模块的电路原理图
图5为本发明提供的LED调光电路的第一预设值、调光数据、调光信号、控制信号和采样电阻的时序图；
图6为本发明提供的LED调光电路第二实施例中恒流源模块的电路原理图；
图7为本发明提供的LED调光电路第三实施例中恒流源模块的电路原理图；
图8为本发明提供的LED调光电路的驱动方法的步骤流程图。
具体实施方式
本发明提供的一种LED调光电路、装置及其调光方法，能够有效解决现有的调光方式中调光深度差的问题。
为使本发明的目的、技术方案及效果更加清楚、明确，以下参照附图并举实施例对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅用以解释本发明，并不用于限定本发明。
请一并参阅图1和图2，本发明提供的LED调光电路，包括控制模块100、数模转换模块200、LED灯串300和恒流源模块400，所述控制模块100连接调光数据输入端、所述数模转换模块200和所述恒流源模块400，所述数模转换模块200还连接所述恒流源模块400，所述恒流源模块400还连接所述LED灯串300的负极，所述LED灯串300的正极连接电源输入端。
其中，所述恒流源模块400包括第一采样电阻Rcs1和/或第二采样电阻Rcs2；所述控制模块100用于将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块400选择所述第一采样电阻Rcs1和/或所述第二采样电阻Rcs2，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块200；所述数模转换模块200用于根 据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块400；所述恒流源模块400根据所述调光信号控制流经所述LED灯串300的工作电流。本发明通过将调光数据与第一预设值进行比较，根据所述调光数据的大小，选择输出不同的亮度数据以及与所述亮度数据对应的采样电阻，进而输出与所述亮度数据对应的调光信号调节所述LED灯串300的工作电流，确保调光数据与所述LED灯串300的工作电流对应关系不变的情况下，有效避免了恒流源模块400的失调电压对调光深度的影响；所述调光数据可以为无线接收器接收到的数据、计数PWM调光信号得到的数据、通过数据总线接收的数据以及ADC(Analog-to-Digital converter)采样得到的数据等。
进一步地，所述控制模块100具体用于比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块400控制其选择所述第一采样电阻Rcs1，并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块200；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块400控制其选择所述第二采样电阻Rcs2，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块200；其中，所述第二采样电阻Rcs2的阻值＝所述第一采样电阻Rcs1的阻值*第二预设值，所述控制模块100通过比较出所述调光数据大小之后，对应控制所述恒流源模块400中的采样电阻的阻值，使得后续所述恒流源模块400根据所述调光信号调节的工作电流与调光数据对应关系不变。
具体实施时，请参阅图3，本发明所述控制模块100包括比较器110、乘法器130和选择器120，所述比较器110的正相输入端连接调光数据输入端，所述比较器110的反相输入端连接第一预设值输入端，所述比较器110的输出端连接所述选择器120和所述恒流源模块400；所述乘法器130的输入端连接调光数据输入端和第二预设值输入端，所述乘法器130的输出端连接所述选择器120，所述选择器120还连接所述数模转换模块200。
其中，所述比较器110用于比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块400，当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块400；所述乘法器130用于将所述调光数据乘以所述 第二预设值后输出至所述选择器120；所述选择器120用于当所述调光数据大于或等于所述第一预设值时，选择输出所述调光数据对应的所述第一亮度数据至所述数模转换模块200，当所述调光数据小于所述第一预设值时，选择所述调光数据乘以所述第二预设值后对应的所述第二亮度数据至所述数模转换模块200。
所述恒流源模块400的失调电压指的是所述恒流源模块400中对应运算放大器的失调电压，所述第一预设值为预先设定的比较参考值，由所述恒流模块中对应的运算放大器的失调电压决定。当所述调光数据变小，调光信号随之变小，当调光信号接近或小于运算放大器的失调电压时，运算放大器的输出不受控，流过LED灯串300的工作电流不受控，则LED灯串300闪烁，调光深度(LED灯串300的工作电流不能调到很低)受运算放大器的失调电压影响。所述第一预设值对应的调光信号应大于运算放大器的失调电压，当所述调光数据小于所述第一预设值时，通过同比例放大调光信号及所述恒流源模块400中采样电阻的阻值，即将调光数据和采样电阻的阻值同时放大所述第二预设值设定的倍数，也就是当所述调光数据小于所述第一预设值时，所述控制模块100控制所述恒流源模块400选择所述第二采样电阻Rcs2，并选择所述调光数据乘以所述第二预设值后对应的所述第二亮度数据至所述数模转换模块200，在保证调光数据与LED灯串300电流对应关系不变的情况下，使得调光信号扩大第二预设值的倍数远远大于运算放大器的失调电压，运算放大器的输出可控，LED灯串300电流可以调到更小，LED灯串300亮度调到更低。
本实施例中，所述第一控制信号为高电平控制信号，所述第二控制信号为低电平控制信后；所述比较器110接收到调光数据之后与第一预设值进行比较，当所述调光数据大于或等于第一预设值时，输出高电平控制信号到所述恒流源模块400，使得所述恒流源模块400选择所述第一采样电阻Rcs1，同时将所述调光数据作为亮度数据输出，也即输出第一亮度数据至所述数模转换模块200；当所述调光数据小于第一预设值时，输出低电平控制信号到所述恒流源模块400，使得所述恒流源模块400选择所述第一采样电阻Rcs1，同时将所述调光数据*第二预设值后作为亮度数据输出，也即输出第二亮度数据至所述数模转换模块200，而所述数模转换模块200输出的调光信号大小则是依据亮 度数据决定的，由此在保证调光数据与所述LED灯串300的工作电流对应关系不变的情况下，调光信号依据亮度数据增大而被放大，进而减小了失调电压对调光深度的影响。
进一步地，请继续参阅图2，所述恒流源模块400还包括选择单元410和恒流源单元420，所述选择单元410连接所述比较器110的输出端，所述恒流源单元420连接所述数模转换模块200，所述第一采样电阻Rcs1的一端和所述第二采样电阻Rcs2的一端均连接所述选择单元410和所述恒流源单元420，所述第一采样电阻Rcs1的另一端和所述第二采样电阻Rcs2的另一端均接地。
所述选择单元410根据所述第一控制信号选择所述第一采样电阻Rcs1，根据所述第二控制信号选择所述第二采样电阻Rcs2；所述恒流源单元420根据所述调光信号控制流经所述LED灯串300的工作电流，所述选择单元410根据所述比较器110输出的控制信号来选择所述第一采样电阻Rcs1或所述第二采样电阻Rcs2接入电路；当所述调光数据大于或等于所述第一预设值时，所述比较器110输出第一控制信号至所述选择单元410，所述选择单元410选择所述第一采样电阻Rcs1接入，对应的所述数模转换模块200也是根据所述第一亮度数据输出的调光信号到所述恒流源单元420；当所述调光数据小于所述第一预设值时，所述比较器110输出第二控制信号至所述选择单元410，所述选择单元410选择所述第二采样电阻Rcs2接入，对应的所述数模转换模块200也是根据所述第二亮度数据输出的调光信号到所述恒流源单元420，由此实现所述控制模块100控制所述恒流源模块400中选择不同阻值的采样电阻，并获取对应亮度数据的调光信号，以便于保证调光数据与所述LED灯串300的工作电流对应关系不变。
进一步地，请继续参阅图2，本发明的第一实施中，所述选择单元410包括第一开关Key1、第二开关Key2、第三开关Key3、第四开关Key4、第五开关Key5、第六开关Key6、反相器INV；所述恒流源单元420包括第一运算放大器OP1、第一MOS管Q1和第二MOS管Q2；所述第一开关Key1的一端和所述第二开关Key2的一端均连接所述第一运算放大器OP1的反相输入端，所述第一开关Key1的控制端连接所述比较器110的输出端，所述第一开关Key1的另一端连接所述第一MOS管Q1的源极和所述第一采样电阻Rcs1的一端；所述第二开关Key2的控制端、所述第四开关Key4的控制端和所 述第五开关Key5的控制端均连接所述反相器INV的输出端，所述第二开关Key2的另一端连接所述第二MOS管Q2的源极和所述第二采样电阻Rcs2的一端；所述第一采样电阻Rcs1的另一端和所述第二采样电阻Rcs2的另一端均接地；所述第三开关Key3的一端和所述第四开关Key4的一端均连接所述第一运算放大器OP1的输出端，所述第三开关Key3的另一端和所述第五开关Key5的一端均连接所述第一MOS管Q1的栅极，所述第四开关Key4的另一端和所述第六开关Key6的一端均连接所述第二MOS管Q2的栅极，所述第五开关Key5的另一端和所述第六开关Key6的另一端均接地，所述第三开关Key3的控制端和所述第六开关Key6的控制端均连接所述比较器110的输出端；所述第一运算放大器OP1的正相输入端连接所述数模转换模块200；所述第一MOS管Q1的漏极和所述第二MOS管Q2的漏极均连接所述LED灯串300的负极，所述反相器INV的输入端连接所述比较器110的输出端，所述LED灯串300的正极连接电源输入端，其中，电源输入端Vin+和电源输出端Vin-接交流电压经整流桥整流后的正端和负端，也可以是开关电源或其它直流电源的输出，因此，本发明中论述的各个元器件的接地对应为连接所述电源输出端Vin-。
本实施例中，请一并参阅图3，当所述比较器110输出高电平控制信号时，所述第一开关Key1、所述第三开关Key3及所述第六开关Key6导通，所述第二开关Key2、所述第四开关Key4及所述第五开关Key5断开，所述第一采样电阻Rcs1接入电路，使得所述恒流源模块400由所述第一运算放大器OP1、所述第一MOS管Q1及所述第一采样电阻Rcs1共同组成，以调节流经所述LED灯串300的工作电流；当所述比较器110输出低电平控制信号时，所述第一开关Key1、所述第三开关Key3及所述第六开关Key6断开，所述第二开关Key2、所述第四开关Key4及所述第五开关Key5导通，所述第二采样电阻Rcs2接入电路，使得所述恒流源模块400由所述第一运算放大器OP1、所述第二MOS管Q2及所述第二采样电阻Rcs2共同组成，以控制流经所述LED灯串300的工作电流，其中，所述第一开关Key1至所述第六开关Key6为MOS开关。
当所述比较器110输出高电平控制信号时，所述恒流源模块400中的采样电阻为所述第一采样电阻Rcs1，所述数模转换模块200输出的调光信号对应的是调光数据，流过 LED灯串300的工作电流＝调光信号/Rcs1；当所述比较器110输出低电平控制信号时，所述恒流源模块400中的采样电阻为所述第二采样电阻Rcs2，此时所述数模转换模块200输出的调光信号对应调光数据*第二预设值，调光信号被放大第二预设值倍，Rcs2＝Rcs1*第二预设值，流过LED灯串300的工作电流＝调光信号/Rcs2，其中，Rcs2为第二采样电阻Rcs2的阻值，Rcs1为第一采样电阻Rcs1的阻值；由此，在保证调光数据与LED灯串300的工作电流对应关系不变的情况下，调光信号电压被放大，减小了运算放大器失调电压对调光深度的影响。
进一步地，请参阅图4，所述数模转换模块200包括分压单元210、译码单元220和多路选择单元230；所述分压单元210对参考电压进行分压后通过不同的抽头输出对应幅值的所述调光信号至所述多路选择单元230；所述译码单元220根据所述第一亮度数据或所述第二亮度数据控制所述多路选择单元230将所述分压单元210对应抽头输出的所述调光信号输出至所述恒流源模块400，通过所述数模转换模块200为所述恒流源模块400提供调光信号，进而实现了工作电流的调节。
具体地，所述分压单元210包括电阻串，所述电阻串由若干个分压电阻串联构成，具体分压电阻的数量可根据实际调光需求进行选择，本发明对此不作限定，所述电阻串的上端连接参考电压输出端Vref，所述电阻串的下端接地；本实施例中所述分压电阻数量为1024个，分别为R0、R1、R2、……、R1021、R1022和R1023，各电阻阻值相等；所述多路选择单元230包括若干个数量与分压电阻对应的控制开关，如图4中K0至K1023，每个控制开关的一端对应连接一个分压电阻的下端抽头，每个控制开关的另一端均连接恒流源模块400，每个控制开关的控制端均连接所述译码单元220，所述控制开关可通过继电器、三极管、MOSFET、传输门等实现。
所述译码单元220接收所述选择器120输出的第一亮度数据或第二亮度数据后，控制对应的控制开关导通或断开，进而选择对应的调光信号输出至所述恒流源单元420，所述控制开关的控制端为高电平时导通，低电平时断开；所述译码单元220采用独热编码，将接收到的所述第一亮度数据和所述第二亮度数据转化为独热码(S0～S1023)后选通各自对应的控制开关，继而选择电阻串对应的调光信号输出至所述恒流源单元420。 本实施例中，亮度数据位宽为10bit，经独热编码后，输出1024个控制信号即独热码S0～S1023，并同时只有一个控制信号为高。
进一步地，请一并参阅图5，本实施例中所述第一预设值和第二预设值均为32，当然第一预设值和第二预设值也可以不同，所述调光数据位宽为10bit，1024级调光，参考电压Vref为3.3V。当所述调光数据由大变小且不小于第一预设值时，所述比较器110输出高电平控制信号，所述恒流源模块400选择采样电阻的阻值为R，对应所述数模转换模块200每级的调光信号的电压＝(3.3V*调光数据)/1024，流过LED灯串300的工作电流＝(3.3V*调光数据)/(1024*R)；当调光数据等于预设值1时，可计算出调光信号为103mV，所述恒流源模块400中的运算放大器在经过校准后，失调电压一般在几十毫伏以下；当所述调光数据再变小，调光信号将接近于失调电压，引起LED灯闪烁，所以通过在调光信号为103mV附近，设定第一预设值，当调光数据小于所述第一预设值时，所述比较器110输出低电平控制信号，所述恒流源模块400对应选择采样电阻的阻值为R*32，对应每级的调光信号电压＝(3.3V*调光数据*32)/1024，流过LED灯串300的工作电流＝(3.3V*调光数据*32)/(1024*32*R)，和所述比较器110输出高电平控制信号时的灯串电流计算方式一致，也就是将采样电阻和调光数据都放大所述第二预设值所设定的32倍，在保证调光数据与LED灯串300的工作电流对应关系不变的情况下，调光信号被放大，减小了运算放大器失调电压对调光深度的影响，从而解决了现有的调光方式中调光深度差的问题。
进一步地，请参阅图6，本发明的第二实施例中，所述选择单元410包括第七开关Key7、第八开关Key8和反相器INV；所述恒流源单元420包括第二运算放大器OP2和第三MOS管Q3；所述第七开关Key7的控制端和所述反相器INV的输入端连接所述控制模块100，所述第七开关Key7的一端和所述第八开关Key8的一端连接所述第二运算放大器OP2的反相输入端和所述第三MOS管Q3的源极，所述第七开关Key7的另一端通过所述第一采样电阻Rcs1接地，所述第八开关Key8的另一端通过所述第二采样电阻Rcs2接地，所述第三MOS管Q3的漏极连接所述LED灯串300的负极，所述第二运算放大器OP2的正向输入端连接所述数模转换模块200，所述第二运算放大器OP2 的输出端连接所述第三MOS管Q3的栅极，所述反相器INV的输出端连接所述第八开关Key8的控制端。
本实施例中，当所述比较器110输出高电平控制信号时，所述第七开关Key7导通，所述第八开关Key8断开，所述第一采样电阻Rcs1接入电路，使得所述恒流源模块400由所述第二运算放大器OP2、所述第三MOS管Q3及所述第一采样电阻Rcs1共同组成，调光信号对应的是调光数据，流过LED灯串300的工作电流＝调光信号/Rcs1；当所述比较器110输出低电平控制信号时，所述第七开关Key7断开，所述第八开关Key8导通，所述第二采样电阻Rcs2接入电路，使得所述恒流源模块400由所述第二运算放大器OP2、所述第三MOS管Q3及所述第二采样电阻Rcs2共同组成，所述数模转换模块200输出的调光信号对应调光数据*第二预设值，调光信号被放大第二预设值倍，Rcs2＝Rcs1*第二预设值，流过LED灯串300的工作电流＝调光信号/Rcs2。
当然，本实施例中可不使用所述第八开关Key8，也能得到同样的结果。也即所述恒流源模块可选择所述第一采样电阻Rcs1和所述第二采样电阻Rcs2，具体为当接收到高电平控制信号时，所述第七开关Key7导通，所述第一采样电阻Rcs1和所述第二采样电阻Rcs2并联，并联后的阻值＝Rcs2/第二预设值；当接收到低电平控制信号时，所述第七开关Key7断开，则所述第二采样电阻Rcs2接入电路；本实施例中的恒流源模块400相比于第一实施例中的恒流源模块400，少连接四个开关和一个MOS管，结构简单，实现成本相对较低。
进一步地，请参阅图7，本发明的第三实施例中，所述选择单元410包括第九开关Key9、第十开关Key10和反相器INV；所述恒流源单元420包括第三运算放大器OP3、第四运算放大器OP4、第四MOS管Q4和第五MOS管Q5；所述第三运算放大器OP3的正相输入端和所述第四运算放大器OP4的正相输入端连接所述数模转换模块200，所述第九开关Key9的一端和所述第三运算放大器OP3的输出端均连接所述第四MOS管Q4的栅极，所述第三运算放大器OP3的反相输入端和所述第四MOS管Q4的源极连接通过所述第一采样电阻Rcs1接地；所述第九开关Key9的控制端连接所述反相器INV的输出端，所述第十开关Key10的控制端和所述反相器INV的输入端均连接所述比较 器110的输出端；所述第十开关Key10的一端和所述第四运算放大器OP4的输出端均连接所述第五MOS管Q5的栅极，所述第十开关Key10的另一端接地，所述第四运算放大器OP4的反相输入端和所述第五MOS管Q5的源极均通过所述第二采样电阻Rcs2接地，所述第四MOS管Q4的漏极和所述第五MOS管Q5的漏极均连接所述LED灯串300的负极。
本实施例中，当所述比较器110输出高电平控制信号时，所述第九开关Key9断开，所述第十开关Key10导通，所述第五MOS管Q5的栅极通过所述第十开关Key10到地，所述第五MOS管Q5不导通，所述第一采样电阻Rcs1接入电路，使得所述恒流源模块400由所述第三运算放大器OP3、所述第四MOS管Q4及所述第一采样电阻Rcs1共同组成，调光信号对应的是调光数据，流过LED灯串300的工作电流＝调光信号/Rcs1；当所述比较器110输出低电平控制信号时，所述第九开关Key9导通，所述第十开关Key10断开，所述第四MOS管Q4的栅极通过所述第九开关Key9到地，所述第四MOS管Q4不导通，所述第二采样电阻Rcs2接入电路，使得所述恒流源模块400由所述第四运算放大器OP4、所述第五MOS管Q5及所述第二采样电阻Rcs2共同组成，所述数模转换模块200输出的调光信号对应调光数据*第二预设值，调光信号被放大第二预设值倍，Rcs2＝Rcs1*第二预设值，流过LED灯串300的工作电流＝调光信号/Rcs2。
基于上述的LED调光电路，请参阅图8，本发明还相应提供了一种LED调光电路的调光方法，具体包括如下步骤：
S100、所述控制模块将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻和/或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；
S200、所述数模转换模块用于根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；
S300、所述恒流源模块用于根据所述调光信号控制流经所述LED灯串的工作电流。
进一步地，步骤S100具体包括：所述控制模块比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块控制其选择所述第一采样电阻， 并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块控制其选择所述第二采样电阻，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块。
基于上述的LED调光电路，本发明还相应提供了一种LED调光装置，包括外壳，所述外壳内设置有PCB板，所述PCB板上设置有如上所述LED调光电路，由于上文对该LED调光电路进行了详细描述，此处不再赘述。
综上所述，本发明提供的LED调光电路、装置及其调光方法，所述LED调光电路包括控制模块、数模转换模块、LED灯串和恒流源模块，所述恒流源模块包括第一采样电阻或第二采样电阻；所述控制模块用于将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻和/或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；所述数模转换模块用于根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；所述恒流源模块用于根据所述调光信号控制流经所述LED灯串的工作电流；本发明能够有效解决现有的调光方式中调光深度差的问题。
可以理解的是，对本领域普通技术人员来说，可以根据本发明的技术方案及其发明构思加以等同替换或改变，而所有这些改变或替换都应属于本发明所附的权利要求的保护范围。

Claims (10)

  1. 一种LED调光电路，其特征在于，包括控制模块、数模转换模块、LED灯串和恒流源模块，所述恒流源模块包括第一采样电阻和/或第二采样电阻；所述控制模块用于将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；所述数模转换模块用于根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；所述恒流源模块用于根据所述调光信号控制流经所述LED灯串的工作电流。
  2. 根据权利要求1所述的LED调光电路，其特征在于，所述控制模块具体用于比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块控制其选择所述第一采样电阻，并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块控制其选择所述第二采样电阻，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块；所述第二采样电阻的阻值＝所述第一采样电阻的阻值*第二预设值。
  3. 根据权利要求2所述的LED调光电路，其特征在于，所述恒流源模块还包括选择单元和恒流源单元；所述选择单元根据所述第一控制信号选择所述第一采样电阻，根据所述第二控制信号选择所述第二采样电阻；所述恒流源单元根据所述调光信号控制流经所述LED灯串的工作电流。
  4. 根据权利要求3所述的LED调光电路，其特征在于，所述选择单元包括第一开关、第二开关、第三开关、第四开关、第五开关、第六开关、反相器；所述恒流源单元包括第一运算放大器、第一MOS管和第二MOS管；
    所述第一开关的一端和所述第二开关的一端均连接所述第一运算放大器的反相输入端，所述第一开关的控制端连接所述控制模块，所述第一开关的另一端连接所述第一MOS管的源极和所述第一采样电阻的一端；所述第二开关的控制端、所述第四开关的控制端和所述第五开关的控制端均连接所述反相器的输出端，所述第二开关的另一端连接所述第二MOS管的源极和所述第二采样电阻的一端；所述第一采样电阻的另一端和 所述第二采样电阻的另一端均接地；所述第三开关的一端和所述第四开关的一端均连接所述第一运算放大器的输出端，所述第三开关的另一端和所述第五开关的一端均连接所述第一MOS管的栅极，所述第四开关的另一端和所述第六开关的一端均连接所述第二MOS管的栅极，所述第五开关的另一端和所述第六开关的另一端均接地，所述第三开关的控制端和所述第六开关的控制端均连接所述控制模块；所述第一运算放大器的正相输入端连接所述数模转换模块；所述第一MOS管的漏极和所述第二MOS管的漏极均连接所述LED灯串的负极，所述反相器的输入端连接所述控制模块。
  5. 根据权利要求3所述的LED调光电路，其特征在于，所述选择单元包括第七开关、第八开关和反相器；所述恒流源单元包括第二运算放大器和第三MOS管；所述第七开关的控制端和所述反相器的输入端连接所述控制模块，所述第七开关的一端和所述第八开关的一端连接所述第二运算放大器的反相输入端和所述第三MOS管的源极，所述第七开关的另一端通过所述第一采样电阻接地，所述第八开关的另一端通过所述第二采样电阻接地，所述第三MOS管的漏极连接所述LED灯串的负极，所述第二运算放大器的正向输入端连接所述数模转换模块，所述第二运算放大器的输出端连接所述第三MOS管的栅极，所述反相器的输出端连接所述第八开关的控制端。
  6. 根据权利要求3所述的LED调光电路，其特征在于，所述选择单元包括第九开关、第十开关和反相器；所述恒流源单元包括第三运算放大器、第四运算放大器、第四MOS管和第五MOS管；所述第三运算放大器的正相输入端和所述第四运算放大器的正相输入端连接所述数模转换模块，所述第九开关的一端和所述第三运算放大器的输出端均连接所述第四MOS管的栅极，所述第三运算放大器的反相输入端和所述第四MOS管的源极连接通过所述第一采样电阻接地；所述第九开关的控制端连接所述反相器的输出端，所述第十开关的控制端和所述反相器的输入端均连接所述控制模块；所述第十开关的一端和所述第四运算放大器的输出端均连接所述第五MOS管的栅极，所述第十开关的另一端接地，所述第四运算放大器的反相输入端和所述第五MOS管的源极均通过所述第二采样电阻接地，所述第四MOS管的漏极和所述第五MOS管的漏极均连接所述LED灯串的负极。
  7. 根据权利要求1所述的LED调光电路，其特征在于，所述数模转换模块包括分压单元、译码单元和多路选择单元；所述分压单元对参考电压进行分压后通过不同的抽头输出对应幅值的所述调光信号至所述多路选择单元；所述译码单元根据所述第一亮度数据或所述第二亮度数据控制所述多路选择单元将所述分压单元对应抽头输出的所述调光信号输出至所述恒流源模块。
  8. 一种基于如权利要求1-7任意一项所述的LED调光电路的调光方法，其特征在于，包括如下步骤：
    所述控制模块将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻和/或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块；
    所述数模转换模块根据所述第一亮度数据或所述第二亮度数据输出对应的调光信号至所述恒流源模块；
    所述恒流源模块根据所述调光信号控制流经所述LED灯串的工作电流。
  9. 根据权利要求8所述的LED调光电路的调光方法，所述控制模块将输入的调光数据与第一预设值进行比较后，根据比较结果控制所述恒流源模块选择所述第一采样电阻或所述第二采样电阻，并选择输出第一亮度数据或第二亮度数据至所述数模转换模块的步骤包括：
    所述控制模块比较出当所述调光数据大于或等于所述第一预设值时，输出第一控制信号至所述恒流源模块控制其选择所述第一采样电阻，并选择输出所述调光数据对应的第一亮度数据至所述数模转换模块；当所述调光数据小于所述第一预设值时，输出第二控制信号至所述恒流源模块控制其选择所述第二采样电阻，并将所述调光数据乘以第二预设值后，选择输出所述调光数据乘以所述第二预设值后对应的第二亮度数据至所述数模转换模块。
  10. 一种LED调光装置，包括外壳，所述外壳内设置有PCB板，其特征在于，所述PCB板上设置有如权利要求1-7任意一项所述的LED调光电路。
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