In order to ensure the illumination level white light led not only obtains the good application, but also obtains the high use efficiency, first is needs to make it satisfies certain application condition, White Light Illuminator secondly is needs to adopt the suitable driving circuit to satisfy the Lde work parameter match request.
A. Drive circuit is a special power supply for the LED, White Light Illuminator to have a simple circuit structure, small footprint, and high conversion efficiency.
B. The output electrical parameters of the driving circuit (current, voltage) to be matched with the technical parameters of the LED, to meet the requirements of the LED, and has a high precision constant current control, White Light Illuminator the appropriate pressure-limiting function. When multiple outputs are output, White Light Illuminator each output can be individually controlled.
C. Has a better linearity of dimming function to meet the different application occasions on the LED luminous brightness regulation requirements.
D. In abnormal state (led open-circuit, short-circuit, White Light Illuminator drive circuit failure), the circuit can be the circuit itself, led and users have a corresponding protective role.
E. Driving circuit work, the normal work of other circuits less interference to meet the relevant electromagnetic compatibility requirements.
Linear drive application is one of the simplest and most direct driving methods. White Light Illuminator In the illumination level white light LED application, although has the low efficiency, the adjustment poor question, but because its circuit is simple, the volume is small, can satisfy the general request, therefore in some special occasions application more.
A. Voltage stabilizer vdd+ Town Flow resistance R mode for the voltage regulator Power + Town flow resistance drive mode, the advantages of the circuit is simple structure, low cost. White Light Illuminator The additional loss on the resistor in series with the LED is larger, and the power consumption of the linear regulator is VDD itself, so the two superimposed together to get the overall efficiency is very low (<50%), and led current control accuracy is low, brightness is not adjustable, so generally only for small power, White Light Illuminator short time lighting occasions, such as LED flashlight, emergency lighting.
B. Steady-current power supply vdd+ Town flow resistance intermolecular electronic switch s way: its advantages not only improve the control precision of LED current, and the brightness of LED can be adjusted by changing the on-off ratio of the electronic switch s. However, because of the high additional losses of the series resistor and the linear steady-current power supply, the overall efficiency is still very low, White Light Illuminator and the specific application range is limited.
The main principle of the circuit is to use the electronic switch s, which is broken according to the requirement, to get the chopping current, to be able to meet the requirements of the LED work, White Light Illuminator the current LF value, through the current negative action (by R0 current sampling) so that the flow through the LED current if stable in a certain range, at the same time can have a certain dimming function. White Light Illuminator The inductance L in the figure is the continuation of the function of storing energy and s turn-off after s opening to reduce the fluctuation of the flow of the LED current.