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  • LM3648 Synchronous Boost LED Flash Driver with 1.5-A High-Side Current Source

    • SNVSA68D October   2014  – November 2016 LM3648

      PRODUCTION DATA.  

  • CONTENTS
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  • LM3648 Synchronous Boost LED Flash Driver with 1.5-A High-Side Current Source
  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
  13. IMPORTANT NOTICE

Package Options

Mechanical Data (Package|Pins)
  • YFF|12
    • MXBG343
Thermal pad, mechanical data (Package|Pins)
Orderable Information
  • snvsa68d_oa
  • snvsa68d_pm
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DATA SHEET

LM3648 Synchronous Boost LED Flash Driver with 1.5-A High-Side Current Source

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

4 Revision History

Changes from C Revision (September 2016) to D Revision

  • Changed "(Default)" from "011111 = 748.75 mA" to "111111 = 1.5 A" in LED Flash Brightness RegisterGo

Changes from B Revision (September 2015) to C Revision

  • Added several additional Applications Go

Changes from A Revision (August 2015) to B Revision

  • Added "or 0x04 for LM3648TT" to Device ID Register row, Register Descriptions tableGo
  • Changed "'011'" to "'000'" in Device Register Bits 5-3 descriptionGo

Changes from * Revision (October 2014) to A Revision

  • Added Torch Currents up to 500 mA (LM3648TT)Go
  • Added Flash Timeout Values up to 1.6 seconds (LM3648TT) Go
  • Changed Handling Ratings to ESD Ratings; moved storage temperature to Abs MaxGo
  • Added ILED row for LM3648TT option Go
  • Added VHR row for LM3648TT option Go
  • Added several new graphs related to LM3648TT option performance Go
  • Added to 1.6 s on LM3648TT in Flash Time-OutGo
  • Added new eq. and LM3648TT values in LED Torch Brightness Reg.; added NOTE below LED Torch Brightness Reg. description Go
  • Added LM3648TT values for Timing Config. Reg.; added NOTE below Timing Config. Reg. description Go
  • Added "or '100'" for LM3648TT in Device ID Register Bits 2-0 descriptionGo
  • Added Application curves for LM3648TT performance Go

5 Pin Configuration and Functions

YFF Package
12-Pin DSBGA
LM3648 LM3648TT 30171802.gif

Pin Functions

PIN TYPE(1) DESCRIPTION
NUMBER NAME
A1 GND G Ground
A2 IN P 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 LM3648.
B1 SW P Drain connection for Internal NMOS and synchronous PMOS Switches.
B2 STROBE I 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 Serial clock input for LM3648.
C1 OUT P Step-up DC-DC converter output. Connect a 10-µF ceramic capacitor between this terminal and GND.
C2 HWEN I Active high enable pin. High = Standby, Low = Shutdown/Reset. Internal pulldown resistor of 300 kΩ between HWEN and GND.
C3 TORCH/TEMP I/P Torch terminal input or threshold detector for NTC temperature sensing and current scale back.
D1 LED P High-side current source output for flash LED. Connect pin D1 to D3 externally.
D2 TX I Configurable dual polarity power amplifier synchronization input. Internal pulldown resistor of 300 kΩ between TX and GND.
D3 LED P High-side current source output for flash LED. Connect pin D1 to D3 externally.
(1) A: Analog Pin, G: Ground Pin, P: Power Pin, I: Digital Input Pin

 
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