1.2-A Dual Flash LED Driver Keeps Heat In Check

The LM3554 drives one or two high-current LEDs for flash applications in handheld devices such as mobile phones, smartphones, and portable scanners. Traditional LED flash drivers sink current from a single high-current LED back into the driver resulting in significant heat dissipation into the driver IC, which can reduce system reliability. The LM3554’s dual LED, high-side current-drive architecture regulates current into two LEDs with cathodes connected directly to the ground. This ground connection provides more effective thermal dissipation while minimizing routing complexity and protecting sensitive circuitry. Due to nonlinearity of LED light output versus LED current, the dual LED architecture consumes less power for the same light output as a single LED. In addition, monitoring pins enable detection of other high-current demands in the system, adaptively throttling the LED current to avoid drawing excessive battery current, which can cause faults or harm the system. The 1.2-A LM3554 is offered in a 16-pin micro SMD package. A complete LM3554-based boost converter design for LED flash measures less than 23 mm². National’s LM3554 is available now and is priced at $2.32 in 1000-unit quantities. NATIONAL SEMICONDUCTOR CORP., Santa Clara, CA. (408) 721-5000.