CN201491339U - LED driving circuit - Google Patents

Abstract

The utility model discloses an LED driving circuit, which comprises a rectifier module, a PWM module, a booster module and an LED actual current detection and feedback module, wherein the output end of the rectifier module is connected with the voltage input end of the PWM module; the switch power supply input end of the PWM module is connected with the LED actual current detection and feedback module; and one end of the booster module is connected with the VCC end of the PWM module, and the other end of the booster module is grounded. The LED driving circuit has the advantages that: the PWM chip controls output; the input voltage is wide; the LED constant current accuracy is high; the circuit efficiency is up to 90 percent; and the circuit calorific power is small; and power is saved.

Description

A kind of led drive circuit

Technical field

The utility model relates to a kind of circuit, especially a kind of LED lighting voltage increase and current constant driving circuit.

Background technology

Existing led drive circuit is in design, for the operating state of the service efficiency that guarantees its power supply and each LED roughly the same, must take all factors into consideration the size of the resistance of the optimum current parameter of each LED and current-limiting resistance, driving DC voltage is low more, the power supply service efficiency is just low more, because the conversion efficiency of reduction voltage circuit generally will be lower than the conversion efficiency of booster circuit; Secondly voltage is low more, the series connection number of LED is just few more, discrete LED parameter error can't adopt the counteracting that adds up of a plurality of series systems, under the constant voltage condition of power supply, for the operating current that guarantees each LED roughly the same, just the resistance of current-limiting resistance be must improve, thereby power supply effective power percentage, inefficiency reduced.

In addition, during constant voltage driving, the LED Devices Characteristics shows as in high temperature and low temperature environment, and its operating current difference is big, because the variation of electric current, the illuminance of light fixture also correspondingly changes, the illuminance instability.

Summary of the invention

The utility model is for solving prior art in use, and the problem of existence provides a kind of stable performance, the led drive circuit of voltage increase and current constant.

The technical scheme that the utility model solves existing issue is: a kind of led drive circuit, described circuit comprises that rectification module, PWM module, boost module, LED actual current detect feedback module, described rectification module output is connected with PWM module voltage input, and described PWM module switch power output end detects feedback module with described LED actual current and is connected; Described boost module one end is connected other end ground connection with PWM module VCC end.

The utility model compared with prior art, its beneficial effect is: by PWM chip controls output, input voltage is wide, LED constant current accuracy height, circuit efficiency is up to 90%; The little economize on electricity of circuit caloric value.

Description of drawings

Fig. 1 is an electrical block diagram of the present utility model.

Embodiment

Referring to Fig. 1, the implementation case comprises: rectification module, PWM module, boost module, Voltage stabilizing module, and described rectification module output is connected with PWM module voltage input, after the rectification module rectification, provides starting resistor by R1 to PWM module chip IC1; Described PWM module switch power output end detects feedback module with described LED actual current and is connected, the field effect transistor Q2 that is connected in the Out end is given in the pulse of PWM module controls chip IC 1 output certain width, the conducting of control field effect transistor Q2 and ending, make inductance produce electromotive force, described boost module one end is connected with the VCC end of PWM module controls chip, other end ground connection, described LED actual current detects feedback module and by resistance R 14 actual current that flows through LED is converted to voltage, sampling R14 voltage and Q2, Q3, R12, R13, C8, R11 constitutes the Vfb end that feedback loop feeds back to IC1, described led circuit also comprises filtration module, filtration module comprises C9 as shown in the figure, C10, C11, four polar capacitors of C12, the electric capacity of inductance and field effect transistor Q2 and filtration module is formed the inductance boost circuit, guarantees the operate as normal of this drive circuit; This drive circuit also is provided with the floating voltage feedback loop in addition, is connected with the Vfb end of chip IC 1 by R9, R10 as shown in the figure, with the restriction floating voltage.

Claims (3)

1. led drive circuit, it is characterized in that: described circuit comprises rectification module, PWM module, boost module, LED current detecting feedback module, described rectification module output is connected with PWM module voltage input, and described PWM module switch power output end is connected with described LED current detecting feedback module; Described boost module one end is connected other end ground connection with the VCC end of PWM module controls chip.

2. led drive circuit as claimed in claim 1 is characterized in that: comprise filtration module, described filtration module is connected between PWM module output and the load.

3. led drive circuit as claimed in claim 1 is characterized in that: described LED current detecting feedback module comprises the loop that resistance (R14) current sample constitutes.

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