SNVS974B April   2013  – October 2015 LM3630A

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 I2C-Compatible Timing Requirements (SCL, SDA)
    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 Operation
        1. 7.3.1.1  Control Bank Mapping
        2. 7.3.1.2  PWM Input Polaritiy
        3. 7.3.1.3  HWEN Input
        4. 7.3.1.4  SEL Input
        5. 7.3.1.5  INTN Output
        6. 7.3.1.6  Boost Converter
        7. 7.3.1.7  Boost Switching Frequency Select
        8. 7.3.1.8  Adaptive Headroom
        9. 7.3.1.9  Current Sinks
        10. 7.3.1.10 Current String Biasing
        11. 7.3.1.11 Full-Scale LED Current
        12. 7.3.1.12 Brightness Register
        13. 7.3.1.13 Exponential Mapping
        14. 7.3.1.14 Linear Mapping
      2. 7.3.2 Test Features
        1. 7.3.2.1 Open LED String (LED1 And LED2)
        2. 7.3.2.2 Shorted LED String
        3. 7.3.2.3 Overvoltage Protection (Manufacturing Fault Detection and Shutdown)
      3. 7.3.3 Fault Flags/Protection Features
        1. 7.3.3.1 Overvoltage Protection (Inductive Boost Operation)
        2. 7.3.3.2 Current Limit
        3. 7.3.3.3 Thermal Shutdown
      4. 7.3.4 Initialization Timing
        1. 7.3.4.1 Initialization Timing With HWEN Tied to VIN
        2. 7.3.4.2 Initialization Timing With HWEN Driven by GPIO
        3. 7.3.4.3 Initialization After Software Reset
    4. 7.4 Device Functional Modes
      1. 7.4.1 LED Current Ramping
        1. 7.4.1.1 Start-Up/Shutdown Ramp
        2. 7.4.1.2 Run-Time Ramp
      2. 7.4.2 PWM Operation
        1. 7.4.2.1 PWM Input
        2. 7.4.2.2 PWM Input Frequency
        3. 7.4.2.3 Recommended Settings
        4. 7.4.2.4 Adjustments to PWM Sampler
          1. 7.4.2.4.1 Filter Strength, Register 50h Bits [1:0]
          2. 7.4.2.4.2 Hysteresis 1 Bit, Register 05h, Bit 7
          3. 7.4.2.4.3 Lower Bound Disable, Register 05h, Bit 6
        5. 7.4.2.5 Minimum TON Pulse Width
    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
    6. 7.6 Register Maps
      1. 7.6.1 LM3630A I2C Register Map
      2. 7.6.2 Register Descriptions
  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 Inductor Selection
        2. 8.2.2.2 Maximum Power Output
      3. 8.2.3 Application Curves
    3. 8.3 Initialization Setup
      1. 8.3.1 Recommended Initialization Sequence
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Output Capacitor Placement
      2. 10.1.2 Schottky Diode Placement
      3. 10.1.3 Inductor Placement
      4. 10.1.4 Input Capacitor Selection and Placement
    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

Package Options

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

1 Features

  • Drives up to 2 Strings of 10 Series LEDs
  • Wide 2.3-V to 5.5-V Input Voltage Range
  • Up to 87% Efficient
  • 8-bit I2C-Compatible Programmable Exponential or Linear Brightness Control
  • PWM Brightness Control for CABC Operation
  • Independent Current Control per String
  • True Shutdown Isolation for LEDs
  • Internal Soft-Start Limits Inrush Current
  • Adaptive Headroom
  • Programmable 16-V/24-V/32-V/40-V Overvoltage Protection
  • Selectable Boost Frequency of 500 kHz or 1 MHz with Optionally Additional Offset
  • Low Profile 12-Pin DSBGA Package
  • Solution Size 32 mm²

2 Applications

  • Smart-Phone LCD Backlighting
  • LCD and Keypad Lighting

3 Description

The LM3630A is a current-mode boost converter which supplies the power and controls the current in up to two strings of 10 LEDs per string. Programming is done over an I2C-compatible interface. The maximum LED current is adjustable from 5 mA to 28.5 mA. At any given maximum LED current the LED brightness is further adjusted with 256 exponential or linear dimming steps. Additionally, pulsed width modulation (PWM) brightness control can be enabled allowing for LED current adjustment by a logic level PWM signal.

The boost switching frequency is programmable at 500 kHz for low switching loss performance or 1 MHz to allow the use of tiny low-profile inductors. A setting for a 10% offset of these frequencies is available. Overvoltage protection is programmable at 16 V,
24 V, 32 V, or 40 V to accommodate a wide variety of LED configurations and Schottky diode/output capacitor combinations.

The device operates over a 2.3-V to 5.5-V operating voltage range and –40°C to +85°C ambient temperature range. The LM3630A is available in an ultra-small 12-bump DSBGA package.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LM3630A DSBGA (12) 1.94 mm × 1.42 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

LM3630A 30200201.gif