SNVAA36 February   2022 LM36010 , LM3642 , LM3643 , LM3644 , LM3648

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Key Specification of LM3644
    2. 1.2 LM3644 Simplified Block Diagram
  3. 2No Boost Inductor Flash Driving Design with LM3644
    1. 2.1 Why Try to Not Use Boost Inductor Solution?
    2. 2.2 No Boost Inductor Schematic of LM3644 for Two LED
    3. 2.3 No Boost Inductor Schematic of LM3644 for Single LED
    4. 2.4 Real Design Sample for No Boost Inductor Design, Torch Mode, Single LED
  4. 3PCB Layout Tips for LM3644 Without Boost Inductor
  5. 4References

2.1 Why Try to Not Use Boost Inductor Solution?

In most smart-phone applications, the UVP threshold of system is more than 3.6 V, and most of LED forward voltage-drops at 1 A or 1.5 A flash current condition is 3 V around, at this condition, flash driver will work in linear mode or bypass mode, it means boost inductor will not participate, at this point, boost inductor prefers a normal copper wire. For designers, they can remove boost inductor to save more PCB area and solution cost.