Features • Accurate and Programmable LED Current up to 1.2A in 128 Steps • Total Solution Size < 30mm 2 • 90% Peak Efficiency • Drives 2 LEDs in Series with 1.2A from 5V Input • Drives 2 LEDs in Series with 600mA from 3.0V Input • Drives 1 LED with 1.2A from 3.0V Input • Adjustable Over-Voltage Protection Allows for Single or Series LED Operation • Four Operating Modes: Torch, Flash, Indicator, and Voltage Mode (4.98V) • Programmable Flash Pulse Safety Timer in 16 Steps • TX Input Ensures Synchronization with RF Power Amplifier Pulse or Prevents LED from Overheating • LED Disconnect During Shutdown • Flash/Imager Synchronization via FEN Pin • Active Low Hardware Reset • Multi-Function Pin ( ^RESET and GPIO) • Low Profile 12-pin LLP Package (SDF12A: 3mm x 3mm x 0.8mm, 0.4mm pitch) Description The LM3553 is a fixed frequency, current mode step-up DC/DC converter with two regulated current sinks. The device is capable of driving loads up to 1.2A from a single-cell Li-Ion battery. One or more high current flash LEDs can be driven in series either in a high power Flash mode or a lower power Torch mode controlled by either an internal register or the FEN pin. Additionally a low current (20mA) indicator mode and a fixed output voltage mode are also available. The LM3553 has 128 current levels and 16 flash safety timer durations that are user adjustable via an I 2C compatible interface. Internal soft-start eliminates large inrush currents at start-up. Over-voltage protection circuitry and 1.2MHz switching frequency allow for the use of small, low-cost output capacitors with lower voltage ratings. The LM3553 includes a TX pin that forces Torch mode during a flash event allowing for synchronization between the RF power amplifier and Flash/Torch modes. It also includes a multi-function pin (M/F) that can serve as a GPIO and a hardware RESET pin. The LM3553 is available in National's 3mm by 3mm LLP12 package. Applications • Camera Phone LED Flash • Smartphone and PDA Flash • LED Backlight

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Datasheet

Title		Size	Date	Other Language
	LM3553 1.2A Dual Flash LED Driver System with I 2 C Compatible Interface	397 Kbytes	6-Mar-08

Featured Application Notes

Title		Size	Date	Other Language
	AN-1780: Application Note 1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface	1427 Kbytes	12-Mar-08

More Application Notes

Title		Size	Date	Other Language
	AN-1495: Application Note 1495 LM3552 White LED Flash Driver Evaluation Board	626 Kbytes	27-Sep-06	中文

Design Tools

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Article - The multiple challenges involved in flash LED driver selection--and how to solve them