The AL3644 is a dual LED flash driver that provides a high level of adjustability within a small solution size. The AL3644 utilizes a 2MHz or 4MHz fixed frequency synchronous boost converter to provide power to the dual 1.5A constant current LED sources. The dual 128 level current sources provide the flexibility to adjust the current ratios between LED1 and LED2. An adaptive regulation method ensures the current sources remain in regulation and maximizes efficiency.
Features of the AL3644 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 2MHz or 4MHz switching frequency options, overvoltage protection (OVP), and adjustable current limit allow for the use of tiny, low-profile inductors and (10μF) ceramic capacitors. The device operates over a –40°C to +85°C ambient temperature range.
Camera Phone White LED Flash
Dual Independent 1.5A LED Current Source Programmability
Accurate and Programmable LED Current Range from 1.4mA to 1.5A
Torch Currents up to 360mA (AL3644TT)
Flash Timeout Values up to 1.6 seconds (AL3644TT)
Optimized Flash LED Current During Low Battery Conditions (Input Voltage Flash Monitor)
> 85% Efficiency in Torch Mode (at 100mA) and Flash Mode (at 1A to 1.5A)
Grounded Cathode LED Operation for Improved Thermal Management
Small Solution Size: < 16mm2
Hardware Strobe Enable (STROBE)
Synchronization Input for RF Power Amplifier Pulse Events (TX)