CN2452246Y

CN2452246Y - LED ultragrace voltage driver

Info

Publication number: CN2452246Y
Application number: CN00255776U
Authority: CN
Inventors: 林文献
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-20
Filing date: 2000-10-20
Publication date: 2001-10-03
Anticipated expiration: 2010-10-20

Abstract

The utility model relates to an LED ultra grace voltage driver, which comprises a DC power supply and a load LED. The utility model is characterized in that the driver also comprises a base frequency f0 square-wave generator, a differential circuit, a self selection regulation circuit with pulse-width duty ratio, a field effect tube power push circuit, an inverter, a field effect tube current pulling circuit, a voltage sample circuit, a precise duty ratio PMW regulation circuit and a voltage tracking circuit. The field effect tube power push circuit and the field effect tube current pulling circuit jointly act to cause the load LED to be in high-brightness working state, and maintain normal junction temperature. The utility model can cause the LED to normally run in ultra grace voltage range.

Description

LED voltage driver of super tolerance

The utility model belongs to lighting field, the driver that particularly a kind of LED works under super tolerance voltage.

As everyone knows, existing LED also is a light-emitting diode.Firmly to adopt pulsed drive LED, its luminosity is improved, but the prerequisite necessary condition of the residing working power of LED is voltage stabilizing, secondly, when voltage is higher, the connection in series-parallel of LED all should be taked all to press or the current-sharing measure, brings very big puzzlement and trouble for thus the application of all many-sides, and corresponding maintenance, maintenance work are also complicated.

The purpose of this utility model provides a kind of driver that can effectively make LED normal operation in super tolerance voltage range, need not the particular power source of high-power voltage stabilizing or constant current.

Task of the present utility model is achieved in that a kind of LED voltage driver of super tolerance, comprises direct current power power supply and load LED, it is characterized in that driver is successively by fundamental frequency f ₀Square-wave generator, differential circuit, the free regulating circuit of pulse duty cycle, the field effect transistor power pushing circuit is formed by connecting, the output of field effect transistor power pushing circuit drives load LED, in addition, the free regulating circuit one tunnel of pulse duty cycle is through inverter, field effect transistor draws current circuit to provide load LED to draw stream, again, be connected to a voltage sampling circuit on the load LED, sampled signal is exported a control signal and is given the free regulating circuit of pulse duty cycle after duty ratio is accurately regulated the PMW circuit, the free regulating circuit of pulse duty cycle also is controlled by the voltage-tracing circuit simultaneously, fluctuation according to power power-supply voltage is made adjustment to the pulsewidth of output in good time, field effect transistor power pushing circuit and field effect transistor draw the current circuit acting in conjunction to make load LED be in the high brightness operating state, DC power supply partly comprises power power-supply and micropower stabilized voltage power supply, and the micropower stabilized voltage power supply provides the working power of drive circuit.

The Design Mechanism of its driver is: the luminosity of LED is proportional to current density basically, is very favourable for adopting pulsed drive, and it can be in the acquisition brightness higher than direct current under average current and the situation that direct current equates; Secondly, the voltage of power power-supply is relevant with the increment of driving LED pulse amplitude.When desiring to make the signal pulse of driving LED effective, it is higher that its effective value should conform with supply voltage, and pulsewidth is narrow more.In the predetermined cycle LED being reached should have current value fully luminous, keep normal junction temperature simultaneously; Moreover the PN junction electric capacity of LED has the stored charge effect, and concerns that with external electrical field exponentially rule the utility model utilizes this intrinsic characteristic to take rational technology path just, and LED can be operated under the super tolerance voltage.

The utlity model has reasonable in designly, simplify and the perfect automatically controlled driving equipment of LED, uprising high electric power system is cheap common power, allows the fluctuation of supply voltage; And the application of having expanded LED, making it step into lighting field provides reliably, tightly beats and cheap technical support, can be widely used in such as industries such as traffic, navigation, aviations.

Below in conjunction with concrete legend the utility model is described further:

Fig. 1 the utility model theory diagram

Fig. 2 the utility model circuit diagram

With reference to Fig. 1, a kind of LED voltage driver of super tolerance comprises direct current power power supply and load LED, it is characterized in that driver is successively by fundamental frequency f ₀Square-wave generator, differential circuit, the free regulating circuit of pulse duty cycle, the field effect transistor power pushing circuit is formed, the output of field effect transistor power pushing circuit drives load LED, in addition, the free regulating circuit one tunnel of pulse duty cycle is through inverter, field effect transistor draws current circuit to provide load LED to draw stream, again, be connected to a voltage sampling circuit on the load LED, sampled signal is exported a control signal and is given the free regulating circuit of pulse duty cycle after duty ratio is accurately regulated the PMW circuit, the free regulating circuit of pulse duty cycle also is controlled by the voltage-tracing circuit simultaneously, fluctuation according to power power-supply voltage is made adjustment to the pulsewidth of output in good time, field effect transistor power pushing circuit and field effect transistor draw the current circuit acting in conjunction to make load LED be in the high brightness operating state, DC power supply partly comprises power power-supply and micropower stabilized voltage power supply, and the micropower stabilized voltage power supply provides the working power of drive circuit.In load LED major loop, be provided with short circuit over-current protection circuit; Between power power-supply and the free regulating circuit of pulse duty cycle, also be provided with the voltage-tracing circuit.

With reference to Fig. 1 and Fig. 2, the circuit in its Fig. 1 block diagram is constructed as follows:

1, power power-supply: for DC power supply 6 to 35V.LED is being subjected to surpass normally operation under the tolerance voltages 6 to 35V under this driver control.

2, micropower stabilized voltage power supply: provide LED drive part circuit required power supply, power power-supply E is through resistance R 1 current limliting and do voltage-stabiliser tube DW1 load, and voltage-stabiliser tube DW1 output voltage stabilizing is at 5V, and C1 is a filter capacitor.The lower voltage limit that voltage-stabiliser tube helps power power-supply E is lower.

3, fundamental frequency f0 square-wave generator: form multi-harmonic-oscillations by ic chip 1, resistance R 2, R3, capacitor C 2, the 3 pin output square wave of IC1.Frequency of oscillation f ₀=1.44/ (R2+R3) C2.IC1 selects time-base integrated circuit 555.

4, differential circuit: for the output that guarantees IC1 accurately triggers IC2,2 pin that then require to be added to IC2 are negative pulses.The output of 3 pin of IC1 is added on 2 pin of IC2 behind the differential circuit of resistance R 5 and capacitor C 4 compositions for this reason.Examining the double amplitude value of filtering differential may occur greater than V _DDPip and insert diode D2, guarantee that with this peak amplitude can be greater than V _DD, R5, C4 network were reference with IC2 output pulse width minimum value, and were elected to be the RC network constant less than this value derivative time.

5, the free regulating circuit of pulse duty cycle: the controlled monostable transient circuit of forming by integrated circuit (IC) 2, resistance R 8, capacitor C 7, the pulsewidth of the 3 pin output of IC2 is that the transient state pulsewidth is controlled by two paths of signals: " controlled monostable " process is: triode BG3, resistance R 8, R11 form the image electric current source, add to the base stage of BG3 from potentiometer VR1 tapping point Vmod voltage signal, when Vmod is healed big, image electric current output is also bigger, be that the linear-charging electric current is also bigger, the C7 charging rate is faster.It is faster to cause IC2 transient state to shorten, and pulsewidth narrows down.Vmod is a cogradient variable of following the tracks of the E voltage swing.This is a controlled monostable signal.Another signal is to come from the 5 foot control system voltage ends that " PWM regulates and control output voltage " signal adds to IC2.This end is the dividing point of the inner 2/3VDD of IC2, is the benchmark voltage of two comparators.Change the voltage of 5 pin of IC2, promptly change IC2 internal comparator upset thresholding, thereby change the pulsewidth that IC2 produces.

Free duty ratio and adjusting thereof:

When the RC timing network that accurately calculates IC2, and from the voltage tolerance scope of E and by making Vmod the voltage-tracing circuit, then the IC2 output pulse width is exactly the basic value under this condition, roughly selects out duty ratio.Factors such as it and load variations are irrelevant.The reference circuit schematic diagram has two frame of broken lines among the figure, the one, power supply E, another is the load major loop, VR1, R14 are peripheral element, other be the design's electronic control module.

Vmod is drawn by the VR1 tapping point, and the design removes user's actuarial formality from, and the design allows tapping point indicating graduation value deviation ± 5 volts.Specifically, E6 to 35 volt is divided into 5 grades, and draws high scale, select the corresponding scale of the tap position of VR1 from the actual voltage value of E.The reference value of Here it is Vmod, E voltage is ± 5 volts of this Vmod deviation fluctuations.

6, duty ratio is accurately regulated pwm circuit: be made up of resistance R 15, R17, R6, R7, R16, diode D3, capacitor C 5, C6 triode BG2 and IC3.The flow through size of the pressure drop actual response load current that its produces of sampling resistor R14 in the LED major loop, electric current.For fear of influencing major loop, R14 generally is very little value, and therefore the pressure drop on R14 is also very little.

The in-phase end of sampled voltage signal input IC3, the 6 pin output of IC3 is synchronized with the variation voltage of sampling, through D3 isolation, C5 bypass, by the grid of current limliting R7 input BG2.

The IC3 output voltage is higher, then heal conducting, i.e. source-drain electrode resistance R of BG2 _SDJust little, on the contrary then bigger.

The charging voltage V of pulsewidth and capacitor C 6 during IC2 output high level _C6With V _DDRatio is relevant, i.e. V _C6Reduce, the charging interval is also just little, and pulsewidth narrows down, otherwise it is big that pulsewidth becomes.

Said process is the effect accurate adjustment IC2 output pulse duty factor of pwm circuit.Power power-supply E fluctuation in a word influences the C7 charging current on the one hand and changes, and on the other hand, cause that load current changes, and the PWM regulating and controlling effect is accurately regulated the IC2 output pulse width, and the suitable current of holding load guarantees reliability service under the normal junction temperature of LED.

7, field effect transistor power pushing circuit: form by diode D5 and triode BG6.

8, field effect transistor is drawn current circuit: be made up of diode D4, triode BG4, BG5 and resistance R 13.

9, inverter: form by diode D4, triode BG4 and resistance R 13.

The power drive of load LED with drawing stream mechanism is: triode BG5 and BG6 are operated under the opposite phase, when IC2 output is high level, and D4, D5 conducting, the BG6 saturation conduction, LED gets.Meanwhile, BG4 is saturation conduction also, and the BG5 grid is low level, BG5 by turn-offing through the collection emitter-base bandgap grading loop of BG4.

Be low level when IC2 exports, D4, D5 end, BG4, BG6 end shutoff, and this moment, the BG5 grid was imported V through R13 _DDBe high level and saturation conduction, the PN junction of LED is in short circuit, and the electron concentration gradient glides rapidly, and the LED major loop disconnects.This process is that drawing of LED flow through journey." drawing stream " is at the influence of the PN junction charge storage effect of eliminating LED, guarantees LED in each pulse period, and PN junction recovers electric neutrality rapidly, thereby keeps normal junction temperature, realizes that LED can normally one of measure of operation in super tolerance voltage range.

10, voltage sampling circuit: for being connected on the resistance R 14 on the load LED major loop.

11, short circuit over-current protection circuit: form by diode D1, voltage-stabiliser tube DW2, triode BG1 and resistance R 4.When occurring short circuit or overcurrent in the major loop, the pressure drop of R14 increases suddenly, and the 4 pin output levels of IC3 are enough to puncture DW2, DW2 is in the snowslide conducting, BG1 is saturation conduction immediately, and 4 pin of IC4 reset terminal by force are low level through the collection emitter-base bandgap grading loop of BG1, and IC1 ends vibration, 3 pin of IC1 are low level, C4 is every directly, and 2 pin of IC2 are high level, and IC2 resets, 3 pin of IC2 are low level, and D4, D5 end.

This moment, the BG6 of major loop ended the shutoff major loop, and load LED has also been protected in the two ends of BG5 conducting short circuit LED, and major loop and power power-supply E disconnect.E also is protected.

12, voltage-tracing circuit: be made up of R12, VR1, R9 and BG3, it is to be connected in parallel on power power-supply E loop, and the size of the Vmod of VR1 tap is synchronized with the variation of E size.Provide the required capacitor C7 charging rate of the monostable transient state of IC2 to change and keep amount synchronously.Be that E voltage increases, the C7 charging rate increases, and the IC2 output pulse width narrows down, otherwise pulsewidth increases.

Claims

1, a kind of LED voltage driver of super tolerance comprises direct current power power supply and load LED, it is characterized in that driver is successively by fundamental frequency f ₀Square-wave generator, differential circuit, the free regulating circuit of pulse duty cycle, the field effect transistor power pushing circuit is formed by connecting, the output of field effect transistor power pushing circuit drives load LED, in addition, the free regulating circuit one tunnel of pulse duty cycle is through inverter, field effect transistor draws current circuit to provide load LED to draw stream, again, be connected to a voltage sampling circuit on the load LED, sampled signal is exported a control signal and is given the free regulating circuit of pulse duty cycle after duty ratio is accurately regulated the PMW circuit, the free regulating circuit of pulse duty cycle also is controlled by the voltage-tracing circuit simultaneously, field effect transistor power pushing circuit and field effect transistor draw the current circuit acting in conjunction to make load LED be in the high brightness operating state, and keep normal junction temperature.

2, LED according to claim 1 voltage driver of super tolerance is characterized in that being provided with short circuit over-current protection circuit in the load LED major loop.

3, LED according to claim 1 voltage driver of super tolerance is characterized in that field effect transistor draws current circuit to be made up of diode D4, triode BG4, BG5 and resistance R 13.