| 摘要 |
A light-emitting element drive device capable of expanding a dimming range of a light-emitting element, enabling a constant minimum dimmed luminance to be obtained irrespective of individual differences between devices. A burst signal generating circuit 12 generates a burst signal Vburst which is a PWM dimming signal generated based on a dimming analogue voltage Vbr indicating a dimming level. This circuit 12 includes an oscillating circuit 24 for generating a triangle wave signal Tri ref, a differentiating circuit 28 for detecting a peak of the triangle wave signal Tri ref, the one-shot timer 30 for generating a signal S2 having pulse width of the duration τ (tau), starting point of which is a peak of the triangle wave signal Tri ref, corresponding to the minimum dimmed luminance of the LED 10, and a NAND circuit 32 for generating the burst signal Vburst based on the comparative result between the voltage level at the triangle wave signal Tri ref and the analogue voltage Vbr when the analogue voltage Vbr does not exceed a predetermined voltage or the burst signal Vburst having pulse width of the duration τ (tau) based on the signal S2 when the analogue voltage Vbr exceeds a predetermined voltage. |
