SNVS796D August   2011  – October 2015 LM3556

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 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 Power-Amplifier Synchronization (TX)
      2. 7.3.2 Input Voltage Flash Monitor (IVFM)
      3. 7.3.3 Fault Protections
        1. 7.3.3.1 Fault Operation
        2. 7.3.3.2 Flash Time-Out
        3. 7.3.3.3 Overvoltage Protection (OVP)
        4. 7.3.3.4 Current Limit
        5. 7.3.3.5 NTC Thermistor Input (TEMP)
        6. 7.3.3.6 Undervoltage Lockout (UVLO)
        7. 7.3.3.7 Thermal Shutdown (TSD)
        8. 7.3.3.8 LED and/or VOUT Fault
    4. 7.4 Device Functional Modes
      1. 7.4.1 Start-Up (Enabling The Device)
      2. 7.4.2 Pass Mode
      3. 7.4.3 Flash Mode
      4. 7.4.4 Torch Mode
      5. 7.4.5 Indicator Mode
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Interface
        1. 7.5.1.1 Data Validity
        2. 7.5.1.2 Start and Stop Conditions
        3. 7.5.1.3 Transferring Data
        4. 7.5.1.4 I2C-Compatible Chip Address
        5. 7.5.1.5 Transferring Data
    6. 7.6 Register Maps
      1. 7.6.1 Register Descriptions
        1. 7.6.1.1  Silicon Revision and Filter Time Register (0x00)
        2. 7.6.1.2  Input Voltage Flash Monitor (IVFM) Mode Register (0x01)
        3. 7.6.1.3  NTC Settings Register (0x02)
        4. 7.6.1.4  Indicator Ramp Time Indicator (0x03)
        5. 7.6.1.5  Indicator Blinking Register (0x04)
        6. 7.6.1.6  Indicator Period Count Register (0x05)
        7. 7.6.1.7  Torch Ramp Time Register (0x06)
        8. 7.6.1.8  Configuration Register (0x07)
        9. 7.6.1.9  Flash Features Register (0x08)
        10. 7.6.1.10 Current Control Register (0x09)
        11. 7.6.1.11 Enable Register (0x0A)
          1. 7.6.1.11.1 Enable Register Mode Bits
          2. 7.6.1.11.2 Control Logic Delays
        12. 7.6.1.12 Flags Register (0x0B)
  8. 8 Application 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
        4. 8.2.2.4 NTC Thermistor 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
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, And Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

1 Features

  • Grounded Cathode LED Operation for Improved Thermal Management
  • 1.5-A High-Side Current Source for Single LED
  • Accurate and Programmable LED Current from 46.9 mA to 1.5 A
  • > 85% Efficiency in Torch Mode (at 100 mA) and Flash Mode (at 1 A to 1.5 A)
  • Small Solution Size: < 20 mm2
  • LED Thermal Sensing and Current Scale-Back
  • Soft-Start Operation for Battery Protection
  • Hardware Enable Pin
  • Hardware Torch Enable
  • Hardware Strobe Enable
  • Synchronization Input for RF Power Amplifier Pulse Events
  • VIN Flash Monitor Optimization
  • 400-kHz I2C-Compatible Interface
  • I2C-Compatible Programmable NTC Trip Point
  • 0.4-mm Pitch, 16-Pin DSBGA Package

2 Applications

    Camera Phone LED Flash

3 Description

The LM3556 is a 4-MHz fixed-frequency synchronous boost converter plus 1.5-A constant current driver for a high-current white LED. The high-side current source allows for grounded cathode LED operation providing flash current up to 1.5 A. An adaptive regulation method ensures the current source remains in regulation and maximizes efficiency.

The LM3556 is controlled via an I2C-compatible interface. Features include: a hardware flash enable (STROBE) allowing a logic input to trigger the flash pulse, a hardware torch enable (TORCH) for Movie Mode or flashlight functions, a TX input which forces the flash pulse into a low-current Torch Mode allowing for synchronization to RF power amplifier events or other high-current conditions, and an integrated comparator designed to monitor an NTC thermistor and provide an interrupt to the LED current. With a fast 1-μs transition from 0 mA to
46.9 mA, the TORCH input pin can be used to develop custom LED current waveforms.

The 4-MHz switching frequency, overvoltage protection and adjustable current limit allow for the use of tiny, low-profile inductors and 10-µF ceramic capacitors. The device is operates over a −40°C to +85°C temperature range.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3556 DSBGA (16) 1.69 mm × 1.64 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application Circuit

LM3556 30171801.gif