The LM3644 is a dual
LED flash driver that provides a high level of adjustability within a small solution size. The
LM3644 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 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 LM3644
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.
For all available packages, see the
orderable addendum at the end of the data sheet.
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