Luminous element drive circuit and method thereof

Abstract

A luminous element drive circuit and a method thereof are disclosed. One end of the luminous element is coupled to a power voltage and the cathode of a diode by an inductor, and the other end thereof is coupled to the anode of the diode. The luminous element drive circuit comprises a switch, a current sensing circuit and a switch control circuit. The current sensing circuit is coupled to the anode of the diode by the switch and used for deciding whether to generate closing control signals according to the breakover current value of the switch. The switch control circuit is used for controlling the breakover and closing of the switch and can close the switch according to the closing control signals. In addition, the switch control circuit is also used for comparing the breakover current value of the switch with a reference current value, so as to generate comparison result to dynamically adjust the time length for closing the switch.

Description

technical field [0001] The present invention relates to a driving circuit and its method, and in particular to a light-emitting element driving circuit and its method. Background technique [0002] figure 1 A conventional LED driving circuit of a buck type with current sensing performed at the source of a MOS transistor and its coupling are shown. The light emitting diode (light emitting diode, LED) driving circuit is composed of a timing generating circuit 202, a positive-edge triggered SR latch 204, an AND gate 206, a switch 208 realized by an NMOS (N-type metal oxide semiconductor) transistor, and a current sense The detection circuit 210 is used to drive the LED string 212 composed of a plurality of LEDs. Of course, the switch 208 may also be composed of PMOS (P-type metal oxide semiconductor) transistors or bipolar junction transistors (bipolar junction transistors, BJT) . . . and other types of transistors. exist figure 1 Among them, one end of the LED string 212 i...

AI Technical Summary

Problems solved by technology

[0005] However, since the timing generation circuit 202 depends on the timing control signal EXCS to change the timing of the conduction control signal TS, when the variation range of the inductor current IL exceeds the maximum current value I MAX with minimum current value I MIN When it is necessary to change the timing of the conduction control signal TS within the defined range, the user must modify the circuit that provides the timing control signal EXCS to change the timing control signal EXCS, otherwise the inductance value of the inductor 214 must be changed, or the The number of light-emitting diodes in the light-emitting diode string 212 can only be reached, causing inconvenience to users

And if the LED driving circuit is made into a circuit chip, there must be an extra pin (pin) to couple with the external circuit that provides the timing control signal EXCS, which also causes design troubles.

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