Driving circuit for driving light source, method and controller

Abstract

The invention provides a driving circuit for driving a load, a method and a controller. The driving circuit comprises a convertor, a transformer, a first inductor and a second inductor. The converter receives input voltage and provides regulated voltage; the transformer converts the regulated voltage into output voltage so as to provide power for the load; when a switch works at a first state, first current flowing through the convertor and second current flowing through the transformer flow through the switch; the first inductor which is coupled between the switch and a first reference node provides a first induction signal for indicating the combined current of the first current and the second current; and the second inductor which is coupled between the first reference node and a second reference node provides a second induction signal which only indicates the second current. With the driving circuit, the method and the controller of the invention adopted, an inductor at the secondary side of the driving circuit and an isolator between the primary side and the secondary side of the driving circuit can be omitted, and therefore, the size and cost of the circuit can be reduced; and the power factor of the driving circuit is corrected, and therefore, power supply quality can be improved.

Description

technical field [0001] The invention relates to a driving circuit, in particular to a driving circuit, a method and a controller for driving a light source. Background technique [0002] figure 1 Shown is a block diagram of a conventional light source driving circuit 100 . The driving circuit 100 is used to drive light sources such as LED strings 108 . The power supply 102 provides the input voltage V IN Provide power to the drive circuit 100 . The driving circuit 100 includes a buck converter that provides a converted voltage VOUT to the LED string 108 under the control of the controller 104 . The buck converter includes a diode 114 , an inductor 112 , a capacitor 116 and a switch 106 . Resistor 110 is connected in series with switch 106 . When the switch 106 is on, the resistor 110 is coupled with the inductor 112 and the LED string 108 to generate a feedback signal indicative of the current flowing through the inductor 112 . When the switch 106 is turned off, the r...

AI Technical Summary

Problems solved by technology

However, the average current flowing through the inductor 112 and the LED chain 108 will be affected by the inductance value of the inductor 112, the input voltage V IN and the influence of the voltage VOUT across the LED chain 108, so it is difficult to precisely control the average current flowing through the inductor 112 (that is, the average current flowing through the LED chain 108)

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