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Use sheet of mixture signal tall voltage piece step-down of machine implementati
From;    Author:Stand originally

LED cultural background

In recent years, LED becomes a kind of feasible burgeoning light source gradually, they had used as merely no longer of electronic equipment " condition indicator light " . Technical progress makes the glow efficiency of LED can amount to incandescent lamp normally 3 times much, in addition, LED is very durable still, life exceeds on 10 thousand hours.

The high-power LED that is aimed at illume application should introduce drive of constant current source, electric current of drive of a few standards often is used in the product of business of different LED production, among them, 350mA and 700mA are most common. The basis strings together the type of coupling and amount, of two end of LED to pressure fall to differ possibly. The high-power LED product of a lot of manufacturers is many more compositive in individual module knot.

A kind of of drive LED simple method is to use series connection resistor to restrict electric current. Linear manostat or operation amplifierAlso can join Cheng Heng sheds configuration. However, the power that this kind of linear method cannot need in place provides enough efficiency below the level.

Switch power source (SMPS) offerred the solution with taller efficiency for LED drive, it can rise input tension / fall to proper n, provide the LED electricity of a need thereby. Limits of systematic input voltage and need LED to pressure fall decided to attack to SMPS develop structural choice.

Step-down - step up converter

When prep above of power supply voltage or the output voltage under need, use step-down - structure of step up converter. To batteries application, step-down - step up converter is very useful. Step-down - step up structure still is called stimulate type instead (Fly-back) transformer or inversion manostat.

Step-down - step up converter can press a plan the means of 1 comes true. This kind of advantage that implements plan is to be able to use simple low end MOSFET driver circuit, its develop attacks photograph of structural general generation is pressed to inputting the positive electricity of voltage course, this one step-down - the defect of plan of step up implementation is load was with circuit ground fiducial.

The circuit that uses PIC16HV785 implements plan

Graph the 2 simple design plan that showed LED drive circuit, used tall tension of a mixture signal among them 8 sheet piece machine, be like PIC16HV785. The output of this circuit is opposite at batteries voltage, potential of ground of and rather than. The output of inverter receives the positive pole of LED repeatedly, the voltage of generation is worth prep above to input voltage.

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