ZAAI Datasheet

Synchronous Boost Dual LED Flash Driver with 1.5-A High-Side Current Sources


The LM3643 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The LM3643 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the dual 1.5-A constant current LED sources. The total LED current the LM3643 boost can deliver is 1.5 A (ILED1 + ILED2 ). The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2 with each driver capable of delivering a maximum of 1.5 A (ex: ILED1 = 1.5 A and ILED2 = 0FF, ILED1 = 0FF and ILED2 = 1.5 A, or a current configuration with a current less than 1.5 A , ILED1 = 950 mA and ILED2 = 250 mA). An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.
Features of the LM3643 are controlled via an I2C-compatible interface. These features include: hardware flash and hardware torch pins (STROBE and TORCH/TEMP), a TX interrupt, and an NTC thermistor monitor. The device offers independently programmable currents in each output leg to drive the LEDs in a Flash or Movie Mode (Torch) condition.
The 2-MHz or 4-MHz switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and (10-µF) ceramic capacitors. The device operates over a –40°C to 85°C ambient temperature range.

• 1.5 A Total Allowed LED Current During Operation
   (ILED1 + ILED2 = 1.5 A)
• Dual Independent LED Current Source
• Accurate and Programmable LED Current Range
   from 1.4 mA to 1.5 A
• Optimized Flash LED Current During Low Battery
   Conditions (IVFM)
• > 85% Efficiency in Torch Mode (@ 100 mA) and
   Flash Mode (@1 A to 1.5 A)
• Grounded Cathode LED Operation for Improved
   Thermal Management
• Small Solution Size: < 16 mm2
• Hardware Strobe Enable (STROBE)
• Synchronization Input for RF Power Amplifier
   Pulse Events (TX)
• Hardware Torch Enable (TORCH/TEMP)
• Remote NTC Monitoring (TORCH/TEMP)
• 400-kHz I2C-Compatible Interface
   – LM3643 (I2C Address = 0x63)
   – LM3643A (I2C Address = 0x67)

   Camera Phone White LED Flash



Manufacturer information


Texas Instruments introduction - Texas Instruments Incorporated (TI) is a global semiconductor design and manufacturing company that develops analog ICs and embedded processors. By employing the world's brightest minds, TI creates innovations that shape the future of technology. TI is helping more than 100,000 customers transform the future, today.

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