CN111901934B

CN111901934B - Multi-path LED constant current driving circuit with same color

Info

Publication number: CN111901934B
Application number: CN201910374168.1A
Authority: CN
Inventors: 刘建华; 江炯同; 张昭荣
Original assignee: Guangzhou Caiyi Light Co Ltd
Current assignee: Guangzhou Caiyi Light Co Ltd
Priority date: 2019-05-06
Filing date: 2019-05-06
Publication date: 2023-02-03
Anticipated expiration: 2039-05-06
Also published as: CN111901934A

Abstract

The invention discloses a multi-path same-color LED constant current driving circuit, wherein the multi-path same-color LEDs are connected in parallel, and the constant current driving circuit comprises: the LED constant current driving IC comprises a control unit, a constant current driving unit and an LED brightness detection and feedback unit, wherein in a parallel same-color LED lamp bead group or a white light module, feedback voltage is amplified through a comparator and then sent to a CPU, and then the CPU judges whether the parallel same-color LED lamp bead group or the white light module has a certain path of lamp bead group which is not bright, so that an input PWM signal of the LED constant current driving IC is adjusted, and corresponding driving currents of the multiple paths of lamp bead groups are matched.

Description

Multi-path LED constant current driving circuit with same color

Technical Field

The invention relates to the field of LED control, in particular to a driving circuit for brightness detection, feedback and current regulation of an LED lamp bead group or a white light module with the same color.

Background

In the prior PAR lamp and strip lamp series products, the LED lamp bead groups with the same color all use independent LED constant current driving circuits. There are also companies that use "parallel LED constant current driving circuits", such as a scheme of high performance fixed frequency current mode control IC UC3843 with NMOS transistor IRFZ44N or a scheme of PWM constant current driving IC SMD802 with NMOS transistor LR 024N.

The parallel LED constant current driving circuit schemes have higher precision on the NMOS tube and the current-limiting resistance of the source electrode of the NMOS tube to the ground, but cannot judge whether the LED lamp bead groups with the same color in parallel connection or the white light module have the phenomenon that a certain path of LED lamp bead group is not bright or not. The current of the 'multi-path lamp bead group' can be adjusted only by the load capacity of the 'NMOS tube source electrode', namely the less the load of the NMOS tube is, the less the current of the 'multi-path lamp bead group', sometimes the current of the 'multi-path lamp bead group' can not be increased any more, and uncertainty exists, particularly the 'multi-path red lamp bead group'.

Disclosure of Invention

The invention aims to solve the problems that the control cost of a plurality of paths of LEDs with the same color is high and whether a single lamp bead is on or not can not be judged to a certain extent, at least provides a commercial application,

therefore, in order to overcome the defects of the prior art, the invention adopts the following technical scheme that a plurality of paths of LEDs with the same color are connected in parallel, and the constant current driving circuit comprises:

the control unit comprises a control chip; the control unit outputs a PWM signal required by the LED constant current driving circuit according to the brightness of the LED;

the signal output end of the constant current driving unit is connected with the anodes of the multiple paths of LEDs with the same color, and constant current is provided for the LEDs according to the corresponding PWM signals;

and the LED brightness detection and feedback unit is connected with the cathodes of the multiple paths of LEDs with the same color and feeds back the brightness of the LEDs to the control chip.

Further, the LED brightness detection and feedback unit comprises a comparator U9, the non-inverting input end of the comparator U9 is connected with the cathodes of the LEDs connected in parallel in the multiple paths, and the inverting input end of the comparator U9 is connected with the AD port of the control chip after being connected with the output end.

Further, the LED aluminum substrate temperature detection circuit further comprises a thermistor detection circuit, and the thermistor detection circuit feeds back temperature information of the LED aluminum substrate to the chip.

Furthermore, the device also comprises a voltage stabilizing circuit.

Furthermore, the device also comprises an anti-creeping circuit.

The LED constant current driving IC has the advantages that in the LED lamp bead group with the same color in parallel or the white light module, the feedback voltage is amplified through the comparator and then is sent to the CPU, and then the CPU judges whether the LED lamp bead group with the same color in parallel or the white light module has the problem that a certain lamp bead group is not bright, so that the input PWM signal of the LED constant current driving IC is adjusted, and the corresponding driving current of the multi-path lamp bead group is matched.

Drawings

Fig. 1 shows a red LED constant current driving circuit.

FIG. 2 is a red LED brightness detection and feedback circuit.

FIG. 3 shows a chip and a peripheral circuit.

Fig. 4 is a wiring diagram of an LED output socket.

FIG. 5 is a thermistor detection circuit.

Fig. 6 shows a DMX512 conversion circuit.

FIG. 7 shows a 5V 3V voltage regulator circuit and a 3V3 voltage regulator circuit and a leakage prevention circuit.

Detailed Description

The circuit and the operation principle of the present invention will be described in detail with reference to the accompanying drawings.

In the embodiment, a circuit and a working principle are introduced on the basis of two red LED control circuits (green, blue and white LEDs adopt the same circuit), and the scheme of the multi-path LED constant current driving circuit with the same color mainly adopts a constant current driving IC LM3409HV of TI company as a main device, and a brightness detection and feedback circuit which takes an LM358 comparator as a main device, an STM32F103RCT6 chip of ST company and peripheral circuits are matched and used.

As the LED constant current driving unit shown in fig. 1, U5 is a constant current driving IC LM3409HV manufactured by TI corporation as a master of the LED constant current driving unit. U1 is a Schmitt trigger produced by TI company, the input end of the Schmitt trigger is connected with a PWM signal end of a control chip, and PWM5 is a pulse width signal of a red lamp bead group as shown in figure 1; the output end of the PWM pulse width signal is connected with the IADJ end and the EN end of the U5, and the PWM pulse width signal sent by the CPU is output. R1 is a pull-down resistor, and prevents the lamp from being electrified and flashing at the moment of lamp bead flashing. R26 and R30 are the locked LM3409HV minimum input voltage. R14, R18 and C12 function to simulate LED current regulation. C16 and R22 are the switching frequencies that set LM3409 HV. Q1 is external PMOS pipe, and Q1 ' S the G utmost point is connected with U5 ' S PGATE end, and the S utmost point is connected with U5 ' S CSN end, CSP end, and Q1 outputs the driving voltage of "red lamp pearl group", and D1 is schottky diode, and the afterflow effect, L1 are the inductance, and the steady output waveform. R34 is a current limiting resistor, and the maximum output current of LM3409HV is set. C20 is the reference capacitance for linearly correcting the output voltage. RF1 is a fuse, CIN1 is a filter capacitor of a power supply input, and D5 is a reverse breakdown diode.

As shown in fig. 2, an LED brightness detection and feedback unit;

u9 is a comparator integrated with a "dual op-amp". And a current-limiting resistor (R78 or R76) is connected to the ground at the negative electrode (R1-or R2-) of each red lamp bead group, and the voltage is detected by the current-limiting resistor. When the feedback voltage is detected, the feedback voltage is input into a comparator and amplified, wherein the indicator light D9 or D10 is turned on or off along with the change of the amplified voltage value, and ZD1 and ZD2 prevent the amplified voltage from exceeding 3.3V and protect the AD port of the CPU. Finally, the voltage signal is input into an AD pin of the CPU, and the CPU converts the voltage value into a brightness value according to the changed voltage value. Because different LED dimming curves are designed in the software program, the LED brightness values corresponding to the DMX values are different.

For example, the full power output of two paths of red lamp bead groups needs 1.4A current, namely the maximum value of PWM numerical output, so that the LM3409HV can drive an external PMOS tube to output 1.4A current. If one of the red lamp bead groups has no feedback of detection voltage (namely the red lamp bead group is not bright) and the other red lamp bead group has full-power output, the full-power output of the red lamp bead group only needs 0.7A current, and the CPU needs to adjust PWM numerical output, so that the LM3409HV can drive an external PMOS tube to output the matched 0.7A current.

In the LED constant current driving circuit, the voltage at two ends of a lamp bead group changes according to the change of an input PWM value of a constant current driving IC, and the current of the lamp bead group changes along with the change of the voltage at two ends of the lamp bead group. When the PWM value is stabilized at a certain value, the voltage at two ends of the lamp bead group is stabilized at a corresponding value, and the current of the lamp bead group is constant at a corresponding value.

As shown in fig. 3, a chip and a peripheral circuit.

U14 is the 32 bit machine chips STM32F103RCT6 of STM32 series, and it outputs the required PWM signal of LED constant current drive circuit, and wherein PWM5 is the pulse width signal of "red lamp pearl group", PWM6 is the pulse width signal of "green lamp pearl group", PWM7 is the pulse width signal of "blue lamp pearl group", and PWM8 is the pulse width signal of "white lamp pearl group".

And feedback voltages ADR1 and ADR2 of two red lamp bead groups, feedback voltages ADG1 and ADG2 of two green lamp bead groups, feedback voltages ADB1 and ADB2 of two blue lamp bead groups, and feedback voltages ADW1 and ADW2 of two white lamp bead groups.

AN1 and AN2 are detection ports of thermistors, LEDS1 and LEDS2 are detection ports of two signal indicating lamps, and TX, RX and RE are transmission, receiving and enabling ports of a DMX512 conversion circuit.

As shown in fig. 4, an LED output socket; as shown in figure 5 is a thermistor sensing circuit,

j1 is an LED output socket which connects two paths of red lamp bead groups and two paths of green lamp bead groups, wherein R + is the parallel end of the two paths of red lamp bead groups, and R1-and R2-are the cathodes of the one path of red lamp bead groups respectively; g + is the parallel end of two paths of green lamp bead groups, and G1-and G2-are the negative electrodes of one path of green lamp bead groups respectively.

J2 is an LED output socket which connects two paths of blue lamp bead groups and two paths of white lamp bead groups, wherein B + is the parallel connection end of the two paths of blue lamp bead groups, and B1-and B2-are the cathodes of the one path of blue lamp bead groups respectively; w + is the parallel connection end of two paths of white lamp bead groups, and W1-and W2-are the negative electrodes of one path of white lamp bead groups respectively.

As shown in fig. 5, HR1 and HR2 are interfaces of two thermistors, and detect the temperature of the lamp bead aluminum substrate through the thermistors, and appropriately adjust the PWM value according to the temperature value fed back, thereby adjusting the current of the "lamp bead group" to achieve the thermal balance of the lamp temperature.

As shown in FIG. 6, the DMX512 conversion circuit, U13 is the master of the DMX512 signal conversion circuit

As shown in FIG. 7, FIG. 7B shows a 5V and 3V3 regulator circuit, U15 is the main device of the 5V regulator circuit, U16 is the main device of the 3V3 regulator circuit, and FIG. 7A shows the anti-leakage circuit composed of RT1 and CAP 1.

Claims

1. The utility model provides a multichannel looks identity colour LED constant current drive circuit which characterized in that, multichannel looks identity colour LED parallel connection, constant current drive circuit includes:

the LED brightness detection and feedback unit is connected with the cathodes of the multiple paths of LEDs with the same color and feeds the brightness of the LEDs back to the control chip;

the constant current drive unit comprises a constant current drive chip U5, a Schmitt trigger U1 and an external PMOS tube Q1, wherein:

the input end of the Schmitt trigger U1 is electrically connected with the PWM signal end of the control chip, the output end of the Schmitt trigger U1 is electrically connected with the IADJ end and the EN end of the constant current driving chip U5, the G electrode of the external PMOS tube Q1 is electrically connected with the PGATE end of the constant current driving chip U5, the S electrode of the external PMOS tube Q1 is electrically connected with the CSN end of the constant current driving chip U5 and the CSP end of the constant current driving chip U5, and the D electrode of the external PMOS tube Q1 is electrically connected with the positive electrodes of the LEDs with the same color in the multiple paths;

the Schmitt trigger U1 is used for outputting PWM signals sent by the control chip to the constant current driving chip U5, and the external PMOS tube Q1 is used for outputting driving voltage to the multiple paths of LEDs with the same color.

2. The constant current driving circuit for the multiple paths of LEDs with the same color as the LED driving circuit of claim 1, wherein the LED brightness detection and feedback unit comprises a comparator U9, the non-inverting input end of the comparator U9 is connected with the negative electrodes of the multiple paths of LEDs connected in parallel, and the inverting input end of the comparator U9 is connected with the AD port of the control chip after being connected with the output end.

3. The multi-path LED constant current driving circuit with the same color as the LED driving circuit of claim 1 or 2, further comprising a thermistor detection circuit, wherein the thermistor detection circuit feeds back temperature information of the LED aluminum substrate to the control chip.

4. The constant current driving circuit for the multiple LEDs with the same color as in claim 1 or 2, further comprising a voltage stabilizing circuit.

5. The multi-path same-color LED constant-current driving circuit according to claim 1 or 2, further comprising an anti-leakage circuit.