National Semiconductor Corporation announced the industry's first high-end LED driver featuring dual-LED camera flash, especially for battery-powered portable multimedia electronics. The LM3554 driver is National's PowerWise®; the latest in an energy-efficient chip family that can drive one or two high-current LEDs, making it ideal for camera-enabled handheld electronics such as mobile phones and smart phones. Mobile phones and portable scanners. Conventional flash LED drivers use current recovery to drive current recovery from high current LEDs. That is, all current is returned to the driver, causing the drive to generate a large amount of thermal energy, which in turn affects the reliability of the system. The LM3554 uses a dual LED high-side current drive architecture to provide a stable drive current for the two LEDs, but the cathode of the LED is directly connected to the ground. This grounding cable design not only enhances heat dissipation, but also simplifies wiring and protects the sensitivity of the circuit. Since the LED light output has a nonlinear relationship with the LED current, even with the same amount of light output, the power consumption of the dual LED architecture is still lower than that of the one LED. In addition, this chip is equipped with a monitoring pin, which can detect whether other circuits of the system are consuming a large amount of current, and flexibly adjust the LED current when needed to avoid the system being faulty or affected by the excessive power consumption of the battery. damage.
The LM3554 is available in a 16-pin micro SMD package. The entire LED flash boost converter solution using National's LM3554 chip is very compact and does not exceed 23mm2;
National Semiconductor's LM3554 LED Driver: Specifications and Features National's LM3554 Flash LED Driver is a fixed-frequency step-up DC/DC converter featuring two stable current sources that can utilize a single Lithium The battery drives loads up to 1.2A. The LM3554 chip can be used in a high-power flash mode to support camera functions. In addition, the drive can also use a low-power flashlight mode to support the video function. System designers can use the I2C-compatible interface to set the drive configuration, adjust the amount of flash current and timer time. In addition, the LM3554 chip also has a built-in timeout protection function to avoid damage to the flash LED due to overheating.
National's LM3554 chip features an adjustable switching current limit function that allows the system to use small inductors with low saturation current. In addition, the chip's 5V power supply can drive LED backlights and power the audio amplifier. The chip features a high-power flash mode and a low-power flashlight mode. When using the flash mode, it can drive two high-current LEDs; in the low-power mode, it can drive a high-current LED, and the built-in register or strobe circuit and TX pin are responsible for switching the control mode. In addition, the system can independently control the associated hardware through the general-purpose input/output (GPIO) pins, so that the hardware reset pin can fully control the operation of the chip once communication problems occur on the I2C interface. The chip also has an internal soft-start feature that suppresses large inrush currents during startup or high frequency switching. The internal soft-start feature also allows the system to use small external components.
The LM3554 is available in a 16-pin micro SMD package. The entire LED flash boost converter solution using National's LM3554 chip is very compact and does not exceed 23mm2;
National Semiconductor's LM3554 LED Driver: Specifications and Features National's LM3554 Flash LED Driver is a fixed-frequency step-up DC/DC converter featuring two stable current sources that can utilize a single Lithium The battery drives loads up to 1.2A. The LM3554 chip can be used in a high-power flash mode to support camera functions. In addition, the drive can also use a low-power flashlight mode to support the video function. System designers can use the I2C-compatible interface to set the drive configuration, adjust the amount of flash current and timer time. In addition, the LM3554 chip also has a built-in timeout protection function to avoid damage to the flash LED due to overheating.
National's LM3554 chip features an adjustable switching current limit function that allows the system to use small inductors with low saturation current. In addition, the chip's 5V power supply can drive LED backlights and power the audio amplifier. The chip features a high-power flash mode and a low-power flashlight mode. When using the flash mode, it can drive two high-current LEDs; in the low-power mode, it can drive a high-current LED, and the built-in register or strobe circuit and TX pin are responsible for switching the control mode. In addition, the system can independently control the associated hardware through the general-purpose input/output (GPIO) pins, so that the hardware reset pin can fully control the operation of the chip once communication problems occur on the I2C interface. The chip also has an internal soft-start feature that suppresses large inrush currents during startup or high frequency switching. The internal soft-start feature also allows the system to use small external components.
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