Light-emitting element driving device with multiple dimming modes and its conversion control circuit

Abstract

The invention provides a light-emitting element driving device with multiple dimming modes and a switching control circuit thereof. The light-emitting element driving device includes: an inductor; a power switch, which is used to switch the inductor to convert the input power to generate an output current to drive the light-emitting element circuit; and a conversion control circuit, including a dimming control circuit. When the dimming signal exceeds the first dimming threshold, the dimming control circuit generates a reference current signal according to the level of the dimming signal to generate a first pulse modulation signal to control the power switch, so that the output current corresponds to the dimming signal level; when the dimming signal does not exceed the first dimming threshold, the reference current signal is clamped so that it corresponds to the level of the first dimming threshold, and the second pulse modulation is generated according to the level of the dimming signal signal, wherein the second pulse modulation signal is used to modulate the first pulse modulation signal to generate a switch control signal to control the power switch.

Description

technical field [0001] The invention relates to a light-emitting element driving device, in particular to a light-emitting element driving device with multiple dimming modes. The present invention also relates to a conversion control circuit used in a light-emitting element driving device with multiple dimming modes. Background technique [0002] Figure 1A and 1B shows a prior art light-emitting element driving device (light-emitting element driving device 1) and its switching control circuit (switching control circuit 15), the light-emitting element driving device 1 uses the switching control circuit 15 to control the power switch SWN to switch the inductance L The input power VDD is converted to generate an output current IOUT for driving the light-emitting device circuit 60 . Figure 1B Among them, the dimming control circuit 50 is used to receive the analog (continuous) dimming signal DIM to generate the reference current signal IREF, and the error amplifier circuit 2...

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Problems solved by technology

[0005] Please also see Figure 4 , which is shown in the figure corresponding to image 3 The schematic diagram of the waveform, image 3 The disadvantage of the prior art shown in is that the ripple of the current ILED of the light-emitting element string 61 is relatively large, especially when the duty ratio of the dimming signal DIM' is low, the current ripple will be more obvious

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