Constant-current LED power supply circuit capable of limiting power supply output power and no-load voltage

Abstract

The invention relates to a constant-current LED power supply circuit capable of limiting power supply output power and no-load voltage, which comprises a constant-voltage power supply module (1) and a DC-DC step-down module (2) arranged at the rear end of the constant-voltage power supply module (1), the circuit further comprises an adjusting module (3) which is respectively connected with the constant current output end of the circuit and the DC-DC voltage reduction module (2) and is used for dynamically adjusting the output current by controlling the DC-DC voltage reduction module (2) when the circuit is in a no-load state and maintaining the output current to a set value through shunting so as to limit the output power of the power supply and the no-load voltage. The method is stable and reliable, and the product performance is improved.

Description

technical field [0001] The invention relates to the technical field of lamp production, in particular to a constant-current LED power supply circuit capable of limiting power supply output power and no-load voltage. Background technique [0002] Based on the characteristics of simple structure, high cost performance and high efficiency, the constant current LED power supply circuit composed of a single-stage constant voltage circuit in the front stage and a DC-DC step-down circuit in the rear stage is widely used in the market. However, the DC output ripple of the single-stage constant voltage circuit is relatively large, which will affect the stability of the circuit. In order to reduce the current ripple output by the LED power supply, the output voltage of the previous stage power supply is usually increased. Due to the input and output of the DC-DC line There is a large voltage difference (the voltage difference is generally above 5V), which will cause the input and outp...

AI Technical Summary

Problems solved by technology

However, the DC output ripple of the single-stage constant voltage circuit is relatively large, which will affect the stability of the circuit. In order to reduce the current ripple output by the LED power supply, the output voltage of the previous stage power supply is usually increased. Due to the input and output of the DC-DC line There is a large voltage difference (the voltage difference is generally above 5V), which will cause the input and output voltage difference of the DC-DC line to reach about 8V while increasing the output voltage of the previous stage power supply.

[0003] However, the increase in the input and output pressure difference of the DC-DC line will cause many problems.

First of all, the LED power supply requires the load power to be increased to the maximum when performing an abnormal test, that is, an overload test. In this case, the output power of the LED power supply will greatly exceed the rated power, and the temperature rise of the components of the LED power supply will rise a lot, and exceed the standard. The maximum temperature value required, causing the LED power supply overload test to fail

[0004] Secondly, increasing the output voltage of the pre-stage power supply will cause the output voltage of the circuit to increase accordingly. If the rated output voltage of the circuit is greater than 35V, the no-load output voltage will increase due to the increase in the input-output voltage difference of the DC-DC line. greater than 42.5V, which is not SELV compliant

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