SNVSA68D October   2014  – November 2016 LM3648

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Flash Mode
      2. 7.3.2 Torch Mode
      3. 7.3.3 IR Mode
    4. 7.4 Device Functioning Modes
      1. 7.4.1 Start-Up (Enabling The Device)
      2. 7.4.2 Pass Mode
      3. 7.4.3 Power Amplifier Synchronization (TX)
      4. 7.4.4 Input Voltage Flash Monitor (IVFM)
      5. 7.4.5 Fault/Protections
        1. 7.4.5.1 Fault Operation
        2. 7.4.5.2 Flash Time-Out
        3. 7.4.5.3 Overvoltage Protection (OVP)
        4. 7.4.5.4 Current Limit
        5. 7.4.5.5 NTC Thermistor Input (Torch/Temp)
        6. 7.4.5.6 Undervoltage Lockout (UVLO)
        7. 7.4.5.7 Thermal Shutdown (TSD)
        8. 7.4.5.8 LED and/or VOUT Short Fault
    5. 7.5 Programming
      1. 7.5.1 Control Truth Table
      2. 7.5.2 I2C-Compatible Interface
        1. 7.5.2.1 Data Validity
        2. 7.5.2.2 Start and Stop Conditions
        3. 7.5.2.3 Transferring Data
        4. 7.5.2.4 I2C-Compatible Chip Address
    6. 7.6 Register Descriptions
      1. 7.6.1  Enable Register (0x01)
      2. 7.6.2  IVFM Register (0x02)
      3. 7.6.3  LED Flash Brightness Register (0x03)
      4. 7.6.4  LED Torch Brightness Register (0x05)
      5. 7.6.5  Boost Configuration Register (0x07)
      6. 7.6.6  Timing Configuration Register (0x08)
      7. 7.6.7  TEMP Register (0x09)
      8. 7.6.8  Flags1 Register (0x0A)
      9. 7.6.9  Flags2 Register (0x0B)
      10. 7.6.10 Device ID Register (0x0C)
      11. 7.6.11 Last Flash Register (0x0D)
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Output Capacitor Selection
        2. 8.2.2.2 Input Capacitor Selection
        3. 8.2.2.3 Inductor Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
      2. 11.2.2 Related Links
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

1 Features

  • 1.5-A LED Current Source Programmability
  • Accurate and Programmable LED Current Range from 1.954 mA to 1.5 A
  • Torch Currents up to 500 mA (LM3648TT)
  • Flash Timeout Values up to 1.6 Seconds (LM3648TT)
  • Optimized Flash LED Current During Low Battery Conditions (IVFM)
  • > 85% Efficiency in Torch Mode (at 100 mA) and Flash Mode (at 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
    • LM3648 (I2C Address = 0x63)

2 Applications

  • Camera Phone White-LED Flash
  • Digital Still Cameras
  • Fire-Alarm Notification
  • Emergency Strobe Lighting
  • Intruder Alert Notification
  • Barcode Scanners
  • Handheld Data Terminals

3 Description

The LM3648 is an LED flash driver that provides a high level of adjustability within a small solution size. The LM3648 utilizes a 2-MHz or 4-MHz fixed-frequency synchronous boost converter to provide power to the 1.5-A constant current LED source. An adaptive regulation method ensures the current source remains in regulation and maximizes efficiency.

Features of the LM3648 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 64 programmable currents in Flash and 128 levels in 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.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3648 DSBGA (12) 1.69 mm × 1.31 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

LM3648 LM3648TT 3648typappnew.gif