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Description

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.

Application

  • Camera Phone White LED Flash

Features

  • 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)
  • Hardware Torch Enable (TORCH/TEMP)
  • Remote NTC Monitoring (TORCH/TEMP)
  • 400kHz I2C-Compatible Interface
    • AL3644 (I2C Address = 0x63)
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)

Product Specifications

Product Parameters

Minimum Input Voltage (V) 2.5
Maximum Input Voltage (V) 5
Maximum Output Voltage (V) N/A
Number of Regulated Output Channels 2
Maximum Output Current per Channel 1500
Typical Over-Current Protection Current N/A
Switching Frequency (MHz) 4
Efficiency (%) 85
Quiescent Current (mA) 0.3
Standby Quiescent Current (?A) 2.5
SW RDS(ON) (?) 65
Dimming I2C
OVP Yes
Soft Start Yes
VFB N/A
Operating Temperature Range -40 to 125

Related Content

Packages
U-WLB1713-12

Applications

Technical Documents

Recommended Soldering Techniques

RoHS CofC

Orderable Part Number Authorized Distributor Quantity Inventory Date Buy Online Region
AL3644CH12-7 Digi-Key Electronics 2990 12/10/2019 Buy Now United States
AL3644CH12-7 Mouser Electronics Inc. 3000 12/10/2019 Buy Now United States
AL3644TTCH12-7 Digi-Key Electronics 3000 12/10/2019 Buy Now United States
AL3644TTCH12-7 Mouser Electronics Inc. 3000 12/10/2019 Buy Now United States

FAQs

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