Self-excited oscillation driving circuit

Abstract

The invention discloses a self-excited oscillation driving circuit which comprises a filtering device, a driving device, a switching device, a sampling device connected with the switching device, and a transformer. The transformer at least comprises a self-excited driving winding. The driving device controls on/off of the switching device. The driving device, the self-excited driving winding, the switching device and the sampling device form a loop. The self-excited oscillation driving circuit is characterized in that the self-excited oscillation driving circuit further comprises a current control device connected into the loop formed by the driving device, the self-excited driving winding, the switching device and the sampling device to further control the switching device.

Description

【Technical field】 [0001] The invention relates to a driving circuit, in particular to a driving circuit of a light emitting diode. 【Background technique】 [0002] With the wide application of light-emitting diode (LED) technology and products, the demand for matching LED drive power is also increasing. In order to reduce the design and production costs of LED drive power, thereby reducing the price of LED lamps, self-excited oscillation circuits are also used. Gaining importance. Such as figure 1 As shown, a non-isolated step-down circuit type self-excited oscillation drive circuit 200 includes a drive power supply 201, a fuse F2, a rectifier bridge 202, a filtering device 203, a starting device 204, a driving device 205, a transformer 206, a switching device 207, and a sampling device 208 . The self-excited oscillation drive circuit 200 of the non-isolated step-down circuit type is used for driving an LED load. The transformer 206 has a self-excited drive winding 209 . ...

AI Technical Summary

Problems solved by technology

However, although the cost of the self-excited oscillation circuit in the prior art is low, since there is no closed-loop feedback of the output current in the self-excited oscillation circuit, and there is no high-precision voltage reference signal similar to the inside of the integrated control chip in the self-excited oscillation circuit, The open-loop control makes the output current change greatly when the input voltage changes and the output load changes

From the actual test results, a figure 2 The product of the step-down circuit self-excited oscillation driving circuit shown in , when the input voltage changes by plus or minus 20%, the output current changes by plus or minus 17% and minus 26%; while the output voltage changes by plus or minus 13% Under normal circumstances, the output current changes by plus or minus 8%. Such a large output current range change will cause a large change in the light output of the LED lamp, which will affect the actual use effect of the lamp, and also affect the heat dissipation design of the lamp and the life of the LED lamp bead. will also have some impact

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