A constant current output circuit and method of a LED drive power supply

Abstract

The present invention detects the peak voltage formed by the inductance current on the external precise resistance through the envelope detection technology, compares it with an internally generated precise reference voltage, and obtains a control voltage, and then uses the control voltage to generate a voltage corresponding to the external inductance current. The changing threshold voltage forces the inductance current to make an opposite change to achieve the purpose of outputting a constant current from the LED drive power supply. This method has a simple structure and is easy to implement. Compared with the conventional open-loop control, it has the following three advantages: 1. It is not sensitive to input voltage fluctuations (open-loop control, no feedback, caused by system delay); 2. It is not sensitive to the inductance value deviation of mass production. Sensitive (open-loop control output current changes with the inductance value); 3, insensitive to LED load voltage changes (open-loop control changes with the load voltage).

Description

technical field [0001] The invention relates to the field of integrated circuit design, in particular to a constant current output circuit of an LED driving power supply. Background technique [0002] LED power supply is a kind of power supply. It is a device that provides power to electronic equipment, also known as a power supply. It is deployed as a different power input on the device connected to an independent circuit device with two or three power inputs. (Light-emitting diodes) dry batteries, etc. are also called power supplies; devices that convert alternating current into direct current through transformers and rectifiers are called rectified power supplies. An electronic device that can provide a signal is called a signal source. The crystal triode can amplify the signal sent from the front and transmit the amplified signal to the subsequent circuit. The transistor can also be regarded as a signal source for the following circuit. Rectified power supply and sign...

AI Technical Summary

Problems solved by technology

[0004] However, the current constant current output of LED power supply generally has fluctuations. For example, input voltage instability, load change, and inductance value deviation will cause fluctuations in the output of LED power supply. Therefore, the existing LED power supply belongs to open-loop output, so it is difficult to realize. True constant current output

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