Isolated primary feedback LED (light-emitting diode) driving circuit with PFC (power factor correction) and controller of driving circuit

Abstract

The invention provides an isolated primary feedback LED (light-emitting diode) driving circuit with PFC (power factor correction) and a controller of the driving circuit. The controller comprises a secondary diode conduction time detection module, a first multiplier, an error amplifier, a negative voltage to positive voltage module, a sampling and holding circuit, a second multiplier, a current sensing comparator, a follower, a zero-crossing detection module and a trigger, an input end of the negative voltage to positive voltage module is connected with a feedback port, an input end of the sampling and holding circuit is connected with an output end of the negative voltage to positive voltage module, an output end of the sampling and holding circuit outputs multiplied signals, a first input end of the second multiplier is connected with an output end of the error amplifier, a second input end of the second multiplier receives the multiplied signals, a first input end of the current sensing comparator receives sampled signals, a second input end of the current sensing comparator is connected with an output end of the second multiplier, the follower follows current reference signals, the zero-crossing detection module is used for generating zero-crossing detection signals, and the trigger generates driving signals according to output signals of the current sensing comparator and the zero-crossing detection signals. The complexity and the cost of a system scheme can be reduced, and efficiency can be improved.

Description

technical field [0001] The invention relates to the field of LED drive circuits, in particular to an isolated primary side feedback LED drive circuit controller with PFC. Background technique [0002] At present, many isolated power supplies, such as mobile phone chargers and high-power LED drivers, usually require the circuit to have the function of outputting constant current due to application requirements. In addition, in order to reduce the harmfulness of power pollution and meet the harmonic standards IEEE555-2 and IEC1000-3-2 of the International Electrotechnical Commission, the above-mentioned isolated power supply must also have a power factor correction (PFC) function. [0003] The commonly used single-stage power factor correction scheme in the prior art is as follows: by detecting the output current of the secondary side of the transformer, after constant current control is performed on the secondary side, it is fed back to the PFC control circuit of the primary ...

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Problems solved by technology

[0021] but, image 3 The LED drive circuit shown also has obvious disadvantages, that is, it is necessary to add the multiplied signal input port VAC and the first resistor divider network 22 in the peripheral main circuit to detect the input voltage Vin, which will increase the complexity and complexity of the system solution. cost, and will result in reduced efficiency

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