White LED is Powered by One NiMH Cell

Published:2012/9/6 20:42:00 Author:Ecco | Keyword: White LED , Powered , One NiMH Cell | From:SeekIC

There are a lot of white LED driver circuits floating around. A popular circuit called the ?Joule Thief? can drive one white LED from a single 1.2v or 1.5v battery cell. Most of these circuits use one or two transistors to form a voltage boost circuit. Yes, they those circuit do drive a LED but they are not very efficient and they don?t do a good job of controlling the current to the LED. The circuit below uses a tiny LT1932 IC made by Linear Technology. This IC can be configured for a wide variety of LED driver needs. I have shown one simple application. The circuit takes power from one 1.2v NiMH rechargeable battery or a 1.5v disposable battery and drives a single white LED with 15ma of current. With an efficiency of about 70%, the circuit should run for about 40 hours, if a quality 2500ma-hour battery is used. Source: discovercircuits



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