SNVSA52E August   2014  – September 2016 LM3644

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Flash Mode
      2. 8.3.2 Torch Mode
      3. 8.3.3 IR Mode
    4. 8.4 Device Functioning Modes
      1. 8.4.1 Start-Up (Enabling The Device)
      2. 8.4.2 Pass Mode
      3. 8.4.3 Power Amplifier Synchronization (TX)
      4. 8.4.4 Input Voltage Flash Monitor (IVFM)
      5. 8.4.5 Fault/Protections
        1. 8.4.5.1 Fault Operation
        2. 8.4.5.2 Flash Time-Out
        3. 8.4.5.3 Overvoltage Protection (OVP)
        4. 8.4.5.4 Current Limit
        5. 8.4.5.5 NTC Thermistor Input (Torch/Temp)
        6. 8.4.5.6 Undervoltage Lockout (UVLO)
        7. 8.4.5.7 Thermal Shutdown (TSD)
        8. 8.4.5.8 LED and/or VOUT Short Fault
    5. 8.5 Programming
      1. 8.5.1 Control Truth Table
      2. 8.5.2 I2C-Compatible Interface
        1. 8.5.2.1 Data Validity
        2. 8.5.2.2 Start and Stop Conditions
        3. 8.5.2.3 Transferring Data
        4. 8.5.2.4 I2C-Compatible Chip Address
    6. 8.6 Register Descriptions
      1. 8.6.1  Enable Register (0x01)
      2. 8.6.2  IVFM Register (0x02)
      3. 8.6.3  LED1 Flash Brightness Register (0x03)
      4. 8.6.4  LED2 Flash Brightness Register (0x04)
      5. 8.6.5  LED1 Torch Brightness Register (0x05)
      6. 8.6.6  LED2 Torch Brightness Register (0x06)
      7. 8.6.7  Boost Configuration Register (0x07)
      8. 8.6.8  Timing Configuration Register (0x08)
      9. 8.6.9  TEMP Register (0x09)
      10. 8.6.10 Flags1 Register (0x0A)
      11. 8.6.11 Flags2 Register (0x0B)
      12. 8.6.12 Device ID Register (0x0C)
      13. 8.6.13 Last Flash Register (0x0D)
  9. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Output Capacitor Selection
        2. 9.2.2.2 Input Capacitor Selection
        3. 9.2.2.3 Inductor Selection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Documentation
      1. 12.2.1 Related Links
      2. 12.2.2 Receiving Notification of Documentation Updates
      3. 12.2.3 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

6 Pin Configuration and Functions

YFF Package
12-Pin DSBGA
LM3644 LM3644TT 30171802.gif

Pin Functions

PIN TYPE DESCRIPTION
NUMBER NAME
A1 GND Ground Ground
A2 IN Power Input voltage connection. Connect IN to the input supply and bypass to GND with a 10-µF or larger ceramic capacitor.
A3 SDA I/O Serial data input/output in the I2C Mode on LM3644.
B1 SW Power Drain Connection for Internal NMOS and Synchronous PMOS Switches.
B2 STROBE I/O Active high hardware flash enable. Drive STROBE high to turn on Flash pulse. Internal pulldown resistor of 300 kΩ between STROBE and GND.
B3 SCL I/O Serial clock input for LM3644.
C1 OUT Power Step-up DC-DC converter output. Connect a 10-µF ceramic capacitor between this pin and GND.
C2 HWEN I/O Active high enable pin. High = Standby, Low = Shutdown/Reset. Internal pulldown resistor of 300 kΩ between HWEN and GND.
C3 TORCH/TEMP I/O Torch terminal input or threshold detector for NTC temperature sensing and current scale back.
D1 LED2 Power High-side current source output for flash LED.
D2 TX I/O Configurable dual polarity power amplifier synchronization input. Internal pulldown resistor of 300 kΩ between TX and GND.
D3 LED1 Power High-side current source output for flash LED.