National Semiconductor has introduced new light-emitting diode (LED) driver that enables dual LED operation for the camera flash function in portable, battery-powered multimedia devices.
The LM3554, a member of the company’s PowerWise product family, reportedly drives one or two high-current LEDs for flash applications in handheld devices, such as, mobile phones, smartphones and portable scanners.
According to the company, traditional LED flash drivers sink current from a single high-current LED back into the driver resulting in heat dissipation into the driver IC. The LM3554’s dual LED sources regulate current into two LEDs with cathodes connected to the ground. This ground connection is claimed to provide thermal dissipation while minimising routing complexity.
The company claimed that the dual LED architecture consumes less power for the same light output as a single LED. The LM3554 flash LED driver is a fixed-frequency, step-up DC-DC converter with two regulated current sources capable of driving loads up to 1.2A from a single-cell Li-Ion battery.
It also features an adjustable switch current limit for the use of small inductors with low saturation currents. The voltage mode offers a 5V rail which can be used for backlight LEDs and audio amplifier supplies.
The company said that one or more high-current LEDs can be driven either in a high-power flash mode or a lower-power torch mode controlled by either an internal register or the strobe and TX pins. A GPIO pin adds a separate hardware control resource to the system. The hardware reset pin offers control over the device in case of I2C communication failure.
