A non-isolated LED constant current drive chip, circuit and method

Abstract

The invention provides a non-isolated LED constant-current driver circuit employing a BUCK framework. The non-isolated LED constant-current driver circuit comprises a high-voltage power supply module for generating DC voltage, a floating current sampling module for sampling current flowing through a power switch tube, and a constant-current driver module for controlling the power switch tube according to the current flowing through the power switch tube to achieve constant-current control on an LED lamp string. By a high-voltage power supply technology, a constant DC power supply is directly generated from a drain end of the power switch tube to provide a chip with electricity, a resisting resistor is omitted, meanwhile, a VCC capacitor can be changed into a low-voltage capacitor with lower cost, the cost of a system is reduced and the complexity of the system is reduced. By a floating sampling technology, a special current sampling pin CS is removed, the driver chip only comprises three pins and cheap encapsulation can be adopted, so that the cost of the chip is greatly reduced. Open circuit protection setting is integrated into the chip, so that the problem of LED twinkling due to the fact that a high-resistance pin ROVP is easily disturbed is solved and the performance is effectively improved.

Description

technical field [0001] The invention relates to the field of integrated circuit design, in particular to a non-isolated LED constant current drive chip, circuit and method. Background technique [0002] LED (Light Emitting Diode, Light Emitting Diode) is a typical current-mode device, and its ideal driving mode is constant current driving, which requires high stability of working current. The non-isolated constant current LED drive circuit is favored by the market due to its simple peripheral circuit and simple control method. [0003] Such as figure 1 Shown is a traditional non-isolated LED constant current drive circuit. The input AC voltage (voltage range is 85-264Vrms) passes through the rectifier bridge and capacitor C0 to obtain a high-voltage DC voltage Vin (called bus voltage), and the bus voltage Vin passes through the starting resistor Rstart The charging current is provided to the capacitor C2 of the chip power supply terminal VCC, and the voltage of the power s...

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Problems solved by technology

[0006] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a non-isolated LED constant current drive chip, circuit and method, which are used to solve the problem of the high complexity of traditional non-isolated LED constant current drive circuits in the prior art. High BOM cost, high-impedance pins are susceptible to interference and cause LED flickering and other problems

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