NS launched the industry's first high-end dual LED flash drive LM3554

National Semiconductor Corporation Ns (National Semiconductor Corporation) announced the launch of the industry's first high-end LED drive, which can support dual LED camera flash, portable multimedia electronic products especially suitable for use in battery powered. This model LM3554 drive is the national semiconductor PowerWise chip? High efficiency series of the latest models, can drive 1 to 2 large current LED, very suitable for handheld electronic products equipped with camera function, such as mobile phone, intelligent mobile phone and portable scanner.

The traditional flash LED driver adopts current recovery mode, which drives the current recovery of high current LED. That is to say, all the current flows back to the driver, so that the driver generates a lot of heat, thereby affecting the reliability of the system. LM3554 chip using dual LED high current drive architecture, can provide stable driving current for two LED, but the LED cathode is directly connected to the ground wire. The design of the grounding wire can not only enhance the cooling capacity, but also simplify the difficulty of wiring, while protecting the sensitivity of the circuit. Due to the LED light output and the LED current has a non-linear relationship, so even if the same amount of light output, the power consumption of dual LED architecture is still lower than the use of 1 LED architecture. In addition, this chip is equipped with monitoring pins, whether other circuit can detect system is a considerable amount of current, current and when there is a need for flexible adjustment of LED, avoid the battery power consumption is too large, resulting in system failure or damage.

LM3554 chip is packaged in 16 pin micro SMD. National Semiconductor LM3554 chip using the entire LED flash boost converter solution size is very small, no more than 23mm2.

National Semiconductor LM3554 LED drives: technical specifications and characteristics

LM3554 LED flash drive national semiconductor is a fixed frequency boost DC / DC converter, which is equipped with two stable current source, can drive the load up to 1.2A using a lithium battery. LM3554 chip can be used in high-power flash mode, to support the camera function. In addition, the driver can also use a low-power flashlight mode to support video recording function. The system design engineer can use the I2C compatible interface to set the configuration of the driver, adjust the flash current and timer time. In addition, the LM3554 chip is also built-in timeout protection function, to avoid the failure of the flash LED damage due to overheating.

The national semiconductor LM3554 chip features an adjustable switching current limiting feature that allows the system to be able to use a small inductor with low saturation current. In addition, this chip 5V power supply can drive LED backlight, but also for audio amplifier power supply. The chip features a high power flash mode and a low power flashlight mode. Using the flash mode, can drive two high current LED; the low power mode, can drive a high current switching LED, and by the built-in registers or gate circuit and the TX pin for control mode. In addition, the system can also be controlled by the universal input / output (GPIO) pin independent hardware, so that once the I2C interface communication problems, the hardware reset pin can be fully control the operation of the chip. The chip also has an internal soft start function, can be started or when the high frequency switch to suppress a large number of inrush current. Internal soft start function is also convenient for the system to use a small external components.