White LED drive circuit composed of TL499A

Published:2011/6/13 6:16:00 Author:Lucas | Keyword: White LED, drive circuit | From:SeekIC

Figure 2-12 shows the white LED drive circuit which is composed of the TM499A. The white LED driver voltage is about 3.6 V. If it uses an ordinary battery to supply power, you need the step-up circuit, and it uses the boost circuit composed of the TL499A. TL499A is an integrated regulator with adjustable output voltage, and when it boosts, it needs switching regulator mode, and when it bucks, it needs the linear regulator mode. The two working modes can change automatically according to the input voltage. Input voltage range is 1.1 10V (switching work), and the maximum voltage is 35V (linear regulator work); the output voltage range is 2.9 to 30V, the maximum output current is 100mA. In the figure, the working power supply is supplied by 1- 2 batteries which are connected in series, and Ip is the controlling peak switch current of pin 4 in TL499A, and when Rl is 5OOΩ, Ip is about 2OOmA.



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