TWM296567U - LED drive circuit having temperature compensation - Google Patents

Description

M296567 VIII. New description: [New technology field] This creation department is about a kind of light-emitting diode (LED) that is full of crying, arguing for lying, and more specifically, this creation involves a kind of A control circuit for controlling the LED driver. [Prior Art] A light-emitting diode driver can control its brightness according to the temperature characteristics of the light-emitting diode. The light emitting diode driver is used to control the current value flowing through the light emitting diode. Although the higher current can enhance the brightness of the LED, it will reduce the lifetime of the LED. Figure i is an existing LED driver circuit. The LED driver circuit is provided with a current ILE:D from a regulated voltage source ι through a resistor 15 to a plurality of LEDs 2 〇 25 25 . Current jled is · ILED^ -VF20 - VF21 - VF25

Rl5 .....................* (Ο where VF2〇~VF25 are the forward voltages of the plurality of light-emitting diodes 20 to 25, respectively. The disadvantage of the existing LED driver shown is the variability of the current lLm. When the forward voltage VF2G~VF25 changes, the current ILED changes accordingly. Due to the mass production and the change of the operating temperature, the forward voltage VF2〇 ~VF25 is not constant. Fig. 2 shows another implementation circuit of the conventional LED driving circuit. The current source % is connected in series with the first body 20 to 25' to the light emitting diode 20 ~25 provides a constant current. However, the above circuit has the disadvantage that the chromaticity and brightness of the light-emitting diode change with the temperature of the light-emitting diode. To maintain the chromaticity and/or brightness of the light-emitting diode. Constantly constant, it must be the same as the temperature of the light. The goal of this creation is to develop a temperature-compensated LED driver. [New content] This creation provides a control for the light-emitting diode Light-emitting diode driving circuit with body brightness. M296567 _Light diode driving The circuit includes a control circuit for generating a light-emitting diode current to control the light-emitting diode. A control terminal of the control circuit is configured to receive a control signal for determining the operation of the light-emitting diode current. a detecting end of the control circuit is turned to the light emitting diode for detecting a light emitting diode voltage. The light emitting diode voltage is used to adjust the light emitting diode current. a first resistor and a second resistor of the control circuit determine a current value of the light-emitting body and an adjustment slope determining a current of the light-emitting diode, wherein the adjusted slope indicates the light-emitting diode current The change corresponds to the change of the voltage of the light-emitting diode. The light-emitting diode is related to the temperature of the light-emitting diode. Therefore, the light-emitting diode current can be adjusted according to the temperature of the light-emitting diode. In order to compensate for the change of the chromaticity and the brightness of the light-emitting diode. [Embodiment] FIGS. 3 and 4 show a plurality of embodiments of the present LED body circuit, wherein the light-emitting diode 20~ 25 is connected in series. A voltage source % is supplied to the light-emitting diodes 2 〇 25 to 25. A control circuit 1 搞 is connected to the light-emitting diodes 20 to 25. Figure 3 shows the power supply of the control circuit Provided by ^ source Vcc. Figure 4 shows that the power supply of the control circuit 1〇〇 is directly supplied by the voltage source v. An output terminal ουτ of the control circuit generates a light-emitting diode current for controlling the light emission. - Pole bodies 20 to 25. A control terminal of the control circuit 1 is for receiving a control signal ν (10) for turning on/off the LED current and determining the current of the two currents. (4) Circuit (10) The detecting terminal VS is connected to the light emitting diodes 20 to 25 for detecting a light emitting diode voltage. The light emitting diode voltage is further used to adjust the light emitting diode current. Further, the through-resistor 57 is connected to the control circuit 1()(), which can be used for the current value of the mosquito light-emitting diode current. Shouted - the second resistor 59 is connected to the control circuit (10), which can be determined by adjusting the slope. The adjustment slope indicates that the change in the light-emitting diode current corresponds to the change in the voltage of the light-emitting diode. The light-emitting diode voltage value is related to the brightness of the light-emitting diode M296567. Therefore, the LED current can be adjusted according to the change in the temperature of the LED to compensate for changes in chromaticity and brightness. To detect the temperature of the light-emitting diode, the light-emitting diode current includes a -first-light diode current I] and a second light-emitting diode current l2. The second illuminating diode current is related to the first illuminating diode current h. The light-emitting diode voltage includes a first light-emitting diode forward voltage 乂 and a second light-emitting diode forward voltage v2. The first-light-emitting diode forward voltage Vi and the second light-emitting diode forward voltage ν2 are respectively generated according to the first-light-emitting diode current Μ second light-emitting diode current. • Fig. 5 shows a circuit diagram of the control circuit 100 of the present creation. The pulse width modulation circuit 200 is coupled to the control terminal of the control circuit lion to generate a first control signal s, which is used to control the duty cycle of the LED current. a sampling circuit _ to the detecting terminal and through the input terminal RT_second resistor 59 of the control circuit 100, and generating an adjustment signal Ia according to the voltage of the LED and the resistance of the second resistor 59. A modulation circuit is connected to the pulse width modulation circuit 200, the sampling circuit 300, and the magic circuit through the control circuit 1 to the first resistor, and is used according to the resistance value of the first resistor 57 and the adjustment signal Ia. A modulation signal ^ is generated. A plurality of sinusoidal force, 72, 74, 75 and 8 〇 form a first current mirror circuit 5 〇〇, according to the first control signal S 〗 and the modulation money IM ′ in the rotation of the control circuit to generate a second light Spread the current. According to the deactivation of the first control signal S!, the LED current is thus switched off. Fig. 6 shows a schematic diagram of the circuit of the modulation circuit 200. The pulse width modulation circuit includes an oscillator 250 for generating a ramp signal RAMP, a second control signal core, a first pulse signal SMpi, and a second pulse signal SMP2. Once the control signal Vcnt is lower than the ramp signal MMp, a first comparator 210 generates a first reset signal RST1. Once the control signal is lower than a threshold signal VTH, a second comparator 215 generates a second reset signal M296567 trace-positive-reverse_235, - inverse 36, - inverted (four), and multiple And qing 232 forms a latch circuit (10) ch c delete it) 'latch circuit _ to the second control signal & first reset signal and second reset signal view. The second control signal & is inverted to provide the enabled clock (cl〇ck) for the flip-flop 235. The second control money & is further connected to the input of the AND and the further input of the gate to the output of the second comparator 215. And the output of the closed (9) is connected to the input end of the reverse or f fine and the input end of the request. And the thinner other input terminal is connected to the output of the first comparator 21〇. The signal output from the output of the 232 is applied to reset the flip flop 235. The output of flip-flop 235 is coupled to the other input of the opposite or idler for generating a first control signal & According to the second control signal &, the latch circuit generates the first control ship number S1. Determining the first control signal according to the second control signal & and according to the first reset signal RST1 and/or the second reset signal according to the second control signal & The falling edge_beer edge and the rising edge (the g produces the first pulse age SMP1 and the second pulse signal SMP2, respectively. Fig. 7 shows the circuit of the vibrator 25〇 of the pulse width modulation circuit 2〇〇 of the present invention. Schematically, a current source 251 is connected to the capacitor through the -switch 253 for charging the capacitor. - The current source 2S2 is connected to the capacitor through the -switch 2M for discharging the capacitor 255. - With - - The trigger point (8) P-p〇int) voltage comparator 261 is connected to the capacitor condition for generating a charge signal when the voltage of the capacitor H 255 is lower than the first trigger point voltage %. - Comparator 26 having a first - trigger point voltage % is coupled to capacitor 255 for generating a -discharge signal once the voltage of capacitor 255 is about the second trigger point voltage V2. A plurality of anti-gate π: and an add-drain latch circuit (RS-latch) are respectively connected to the charging signal and the discharging signal. Thus, the output of the gate 262 is reversed to produce a second control signal S2. Through the inverter, the second control signal is connected to a pulse generating M296 567 for generating the first pulse signal 8?41>1. The second control signal is phantomly coupled to a pulse generator 280 for generating a second pulse signal SMp2. The second control signal heart and the output of the inverter are connected "for control of switches 254 and 253, respectively. A ramp signal RAMp is generated at capacitor 255. Figure 8 is a circuit diagram of the sampling circuit 3, wherein a plurality of operational amplifiers 3i, 32, and 305, 306, 307, 308, 31 312 form a first differential circuit (differential Circmt) 301. Resistors 305 and 306 form a voltage divider that is coupled from the sense terminal of control circuit 1 to the input of sense amplifier 310 for detecting the LED voltage. The resistors 3〇7 and 3〇8_ form a further voltage divider connected from the output terminal 〇υτ of the control circuit hall to the input terminal of the operational amplifier 32A. The operational amplifier 320 operates as a buffer. The operational amplifier 31 is connected to resistors 311 and 312 and operates as a differential amplifier. Therefore, the operational amplifier 31 outputs the signal difference between the detection ^ vs and the output 'OUT. The above difference represents the light-emitting diode voltage. A switch and capacitor 326 form a -sampling circuit. A switch 327 and a capacitor 328 form a second sampling circuit 1 and the switches 325 and 327 are controlled by the first pulse signal SMP1 and the second pulse signal SMp2, respectively. The output of the operational amplifier 310 is coupled to a first sampling circuit and a second sampling circuit. Therefore, according to the first pulse signal, the first sampling circuit samples the first light-emitting diode forward voltage V! of the light-emitting diode voltage. According to the second pulse signal SMp2, the second sampling circuit samples the second light-emitting diode forward voltage ^ of the light-emitting diode voltage. A plurality of operational amplifiers 33(), 34A, transistors 34, 342, 343 and resistors 335, 345 form a second differential circuit 〇2 connected to the first sampling circuit and the second sampling circuit for The difference between the first illuminator forward s % and the second illuminator forward voltage v2 produces a _ differential signal. Capacitor 328 and switch 327 are coupled to the input of the operational amplifier 340. The operational amplifier 34 is used as a buffer. Capacitor 326 and switch 3 are coupled to the input of the differentiated state 330. The operational amplifiers 33A, 34A, resistor 335 and transistor M296567 341 generate a current 1341. Transistors 342 and 343 form a first current mirror coupled to current 1341 for generating a current 1343. Current 1343 and resistor 345 generate a differential signal. An operational amplifier 350 and a plurality of transistors 35, 352, 353, 354, 367, 368 form a voltage to current converter. The input of the differential amplifier 350 receives the differential signal. The other input terminal of the operational amplifier 35A is connected to the second resistor 59 through the RI terminal of the control circuit 1GG. Therefore, the voltage-to-current converter generates the adjustment signal Ia based on the differential signal and the resistance value of the second resistor 59. A resistor 37 is coupled from the transistor 351 through the RI terminal to the second resistor 59 for protecting the voltage to current converter from shorting the second resistor 59 through the RI terminal. Fig. 9 shows the modulation circuit 4 of the control circuit 1 of the present creation. An operational amplifier 41 〇 and - transistor 411 form a current generator. A reference voltage Vr is connected to the input of the operational amplifier 41A. The other input terminal of the operational amplifier 410 is coupled to the first resistor 57 through an input terminal 控制 of the control circuit 1 , for generating a reference current 1411 based on the reference voltage Vr and the resistance value of the first resistor 57. A resistor 47A is connected from the transistor 411 to the first resistor 57 for protecting the current generator from being short-circuited with the first resistor 57. The plurality of transistors 412 to 418 form a second current mirror circuit ♦ 480 for generating a modulation number based on the reference current and the adjustment signal u. The transistors, 413 and 414 form a second current mirror for generating the electrodes il 1413 and 1414 based on the reference current 1411 and the adjustment signal Ia. Transistors 415 and 416 form a third current mirror for generating a current 1416 based on current 1413. Transistors 417 and 418 form a fourth current mirror for generating a current 1418 based on current dithering. A t-modulation signal IM is generated based on currents 1416 and 1418. The first control signal S1 is transmitted to a transistor 430 through the inverter 420. The transistor 430 is further coupled to the second current mirror for cutting off the currents I4i3 and 1414 according to the first control 旒5旒S. A transistor 431 is coupled to the third current mirror for cutting the current 1416 according to the second control signal. Therefore, the modulation signal Im is enabled in accordance with the enablement M296567 of the first control signal S1 to generate the first-light-emitting diode current. The modulation signal Im' is further controlled in accordance with the second control signal S2 to produce a second LED current 2. Fig. 10 shows the waveform of the first control signal S!, during which the first control signal & is generated by comparing the control signal VCNT with the ramp signal mmp during the ramp-up ramp period. second

The control signal S2 is generated during the falling period of the ramp signal RAMP. The modulation signal IM is disabled (low level) according to the failure (high level) of the control signal & The modulation money IM is controlled according to the enablement (low level) of the first control signal §1 to generate the first light emitting diode current ^, and according to the enablement (high level) of the second control signal s2, the chirp is generated. The second illuminating diode current l2. In the first light-emitting diode current period of 1 丨, the vibration in 250 generates a first pulse signal SMp, and the first light-emitting body forward voltage V1 is sampled. In the second light-emitting diode current l2 period process, the vibrator (4) generates a second pulse signal SMP2 to sample the second light-emitting diode forward voltage. Therefore, the first light-emitting diode current direction can be defined according to the first-light diode current 1] and the second county diode current l2 ’

Voltage % 'and confirm the second illuminating diode forward voltage %, where the current 1 core 2 can be known by the following formula: AU = \〇xevllVT ........ —(5) ~(6) ...( 7) \2 = \〇xeV2/VT ....... VT = kx Temp q and Temp is where k疋 Boltzmann constant (B〇itzmann, s , q is the absolute temperature of the electron charge. (8)

Temp Κ Ιηώ 12 From the above equation, it can be seen that the temperature of the light-emitting diode can be accurately detected from the light-emitting diode voltage by 11 M296567 degrees. Therefore, the temperature of the light-emitting diode is further used to adjust the light-emitting diode current to compensate for the chromaticity and brightness of the light-emitting diode.

As mentioned above, it is only a detailed description and drawing of the specific embodiment of one of the best creations of the present invention, and any one who is familiar with the skill of the artist in the field of the present invention has the patent scope of the present invention. The change or modification that can be easily thought of can be covered by 12 M296567 [Simple description of the drawing] Fig. 1 is a schematic circuit diagram of a conventional LED driving circuit. FIG. 2 is a schematic circuit diagram of a conventional dual-light-emitting diode driving circuit. Figure 3 is a first preferred embodiment of the present invention. Figure 4 is a second preferred embodiment of the creation. Figure 5 is a schematic circuit diagram of the control circuit of the present invention. Figure 6 is a circuit diagram of the pulse width modulation circuit in the control circuit of the present invention. Lu P diagram is a circuit diagram of the oscillator of the pulse width modulation circuit in the control circuit of the creation. Figure 8 is a circuit diagram of the sampling circuit in the control circuit of the present invention. Figure 9 is a circuit diagram of the modulation circuit in the control circuit of the present invention. Figure 10 is a schematic diagram of the signal waveform of the control circuit of the present invention. [Main component symbol description] Adjust voltage supply 10 Current Ili: D Current source 35

Light-emitting diode (20, 21···25) Control circuit 100 Output terminal OUT Control signal VCNT First resistor 57 First light-emitting diode current I: Resistor 15

Diode (2〇, 21···25) Forward 1: Pressure vF2. ~Vf25 voltage source vIN voltage source control terminal IN detection terminal Vs second resistor 59 second light emitting diode current L 13 second light emitting diode forward voltage V2 first control signal Si adjustment signal IA modulation signal IM, operation Amplifier 310, 320, 330, 340, 350, 410 Ramp signal RAMP First pulse signal SMP1 Control k number ν 〇ΝΤ First reset signal RSI1 Second comparator 215 Forward 235 Inverter 230, 264, 420 Current Source 251, 252 capacitors 255, 326, 328 comparators 260, 261 opposite gates 262 and 263 first current mirror circuit 500 currents 1341, 1343, 1413, 1414, 1416, 1418 M296567 first light-emitting diode forward voltage v , pulse width modulation circuit 200 sampling circuit 300 modulation circuit 400 transistors 71, 72, 74, 75, 80, 34 342 343, 35 352, 353, 354, 367, 368 411 ~ 418, 430 • oscillator 250 Second control signal S2 Second pulse signal SMP First comparator 210 Critical signal Vth Second reset signal RST2 Reverse or gate 236 Call gate 23 232 Switch 253, 254 First trigger point voltage 乂! Second trigger point voltage V2 pulse generator 270, 280 resistor 305, 306, 307, 308, 3U, 312, 370, 470 14 M296567 switch 325, 327 second differential circuit 302 reference voltage VR reference current 1411

Resistor 335, 345 first differential circuit 301 input terminal RI second current mirror circuit 480

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Claims (1)

M296567 IX. Patent Application Range·· 1. A light-emitting diode driving circuit, comprising: a control circuit for generating a “light-emitting diode current” of a control light-emitting diode; a third-dimensional resistance port connected to the control a circuit for determining a current value of the light-emitting diode current; a fresh-form for the receiving path to determine a duty cycle of the light-emitting diode current; a detecting end of the circuit Reduction to the light-emitting diode for detecting a light-emitting diode voltage 'where the stray light diodes are tunable to the core-lighting diode current; and _ the first resistor, connected to the control circuit, the secret determines the 1 full slope The adjustment slope of the towel indicates that the change of the 1 -pole current corresponds to the change of the voltage of the LED. 2. The LED driving circuit of claim 2, wherein the LED current comprises a first LED current and a second LED current; the second LED Polar body electric 4 Haidi - hair thin side; _: very fine new - first - forward voltage and one: two axis ", (four) fine - Chen extremely fine no body current respectively generated the first forward voltage and the second Forward voltage. 3. The illuminating diode driving circuit according to the item ii, wherein the control circuit comprises: a pulse width modulation circuit coupled to the control terminal for generating a _ _ photodiode current red a period of time; I 4 to control the sampling private circuit, lightly connected to the detecting end and the second resistor to observe the resistance value of the second resistor to generate an adjustment signal; trending stray diode power, - modulation circuit Up to the first resistor, the pulse width modulation circuit, and the first current mirror circuit coupled to the pulse width modulation circuit by the 16 M296567 according to the first and the lion's And the 亥 调制 modulation circuit is configured to generate the illuminating diode current according to the first control signal and the modulating signal. 4. The illuminating diode driving circuit according to claim 3, wherein the pulse width modulation circuit comprises: - a device, a flipping signal, a second control signal, a - a pulse signal, and a a second pulse signal; - a first comparison buffer, which is generated when the control signal is less than the ramp signal - a first reset signal; - a second comparator for generating a control signal lower than - a critical signal generation a second reset signal; and a latch circuit, which is input to the second control number, and the second control number generates the first control signal; wherein the first control signal is deactivated according to the second control signal The root_first-reset signal and the second reset signal are respectively generated by the money-control succession effect, and the first pulse signal and the first phase are generated respectively according to the falling edge and the rising edge of the second control hall number Two pulse signals. 5. The LED driving circuit of claim 4, wherein the first reset signal or the second reset signal disables the first control signal. 6. The illuminating diode driving circuit of claim 3, wherein the sampling circuit comprises: a first differential circuit coupled to the detecting end for detecting the voltage of the illuminating diode; a sampling circuit for sampling the first forward voltage of the LED voltage according to the first pulse signal; a second sampling circuit 'for illuminating the LED voltage according to the second pulse signal The second forward voltage is sampled; 17 M296567 - a first-difference "path for generating a differential signal based on a difference between the first-axis voltage and the second forward voltage; and a voltage-to-current converter And _to the second electric_, the service generates the adjustment signal according to the differential signal and the resistance value of the second resistor. 7. The illuminating diode circuit of the third embodiment of the present invention, the modulation circuit comprising: - current generating H' for generating a reference according to the reference voltage and the resistance value of the first resistor Current; and __the second recording circuit 'Lin' is capable of testing the current and the signal of the whole button; wherein the enabling of the first control signal enables the modulated signal to generate the first light emitting diode The electromuscular 'and controls the sizing signal according to the second control signal for generating the second illuminating diode current. 8. A light-emitting diode controller, comprising: - a control circuit that converts to generate a light-emitting diode current of the light-emitting diode; and a control terminal of the control circuit for receiving and determining the light-emitting diode a control signal of the body current; and a detecting end of the control circuit coupled to the light emitting diode for detecting a light emitting diode voltage, wherein the light emitting diode voltage is used to adjust the light emitting diode Body current. 9. The illuminating diode controller of claim 8, further comprising: a first resistor coupled to the control circuit for determining a current value of the illuminating diode current; The resistor is consuming to the control circuit for determining an adjustment slope, wherein the adjustment slope indicates that the change of the LED current corresponds to the change of the LED voltage. The illuminating diode controller of claim 8, wherein the illuminating diode current comprises a first illuminating diode current and/or a second illuminating diode current, the second The light emitting diode current is related to the first light emitting diode current' and the light emitting diode voltage includes a first forward voltage and a second forward voltage, wherein the first light emitting diode current and the The second light emitting diode current generates the first forward voltage and the second forward voltage, respectively. 11. The illuminating diode controller of claim 8, wherein the control circuit comprises: a pulse width modulation circuit coupled to the control terminal for generating a first control signal to control the transmission# a working period of the photodiode current; - a sampling circuit, the _ to the syllabus is used to generate an adjustment signal according to the luminosity reduction; a modulation circuit coupled to the pulse width modulation circuit and the sampling circuit to generate a a modulation signal; and a first current mirror circuit for engaging the pulse width modulation circuit and the modulation circuit with a control signal and the modulation signal to generate the LED current. For the purpose of And a second pulse signal; the pulse width modulation circuit comprises: a second control signal, a first pulse signal and a first comparator, a second comparator, configured to generate a second reset-latch circuit coupled to the second control signal when the control signal is less than 'generating a first reset signal; and a threshold signal And generating the 19th M296567 control signal according to the second control signal; wherein the first control signal is enabled according to the second control signal, according to the first reset signal and the second reset signal The first control signal is disabled, and the first pulse signal and the second pulse signal are respectively generated according to the falling edge and the rising edge of the second control signal. 13. The illuminating diode controller of claim 12, wherein the first reset signal or the second reset signal disables the first control signal. 14. The illuminating diode controller of claim 11, wherein the sampling circuit comprises: a first differential circuit coupled to the detecting end for detecting the voltage of the illuminating diode; a first sampling circuit, configured to sample the first forward voltage of the LED voltage according to the first pulse signal; and a sampling circuit for the LED according to the second pulse signal Sampling the second forward voltage of the voltage; a second differential circuit for generating a differential signal according to the difference between the first forward voltage and the second forward voltage; and I-voltage-to-current conversion And generating the adjustment signal according to the differential signal. 15. The illuminating diode controller of claim 11, wherein the modulating circuit comprises: a current generator for generating a reference current according to a reference voltage; and a current mirror circuit 'for The reference current and the adjustment signal generate the modulation signal; wherein the enabling of the control signal is such that the modulation k number is generated to generate the first LED current, and according to the second control signal The modulated signal is controlled for generating the second light emitting diode current. 20