SNVS553C January   2008  – November 2016 LM3407

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 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 Floating Buck Switching Converter
      2. 7.3.2 Pulse Level Modulation (PLM)
      3. 7.3.3 Internal VCC Regulator
      4. 7.3.4 Clock Generator
      5. 7.3.5 PWM Dimming of LED String
      6. 7.3.6 Input Under-Voltage Lock-Out (UVLO)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Low-Power Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Switching Frequency Selection
      2. 8.1.2 LED Current Setting
      3. 8.1.3 Input and Output Capacitors
      4. 8.1.4 Selection of Inductor
      5. 8.1.5 Free-Wheeling Diode
    2. 8.2 Typical Applications
      1. 8.2.1 LM3407 Design Example
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Calculate RISNS
          2. 8.2.1.2.2 Calculate RFS
          3. 8.2.1.2.3 Choose L
          4. 8.2.1.2.4 Choose CIN and CVCC
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Typical Application for Driving 6 LEDs
      3. 8.2.3 Typical Application for Driving 1 LED
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    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

5 Pin Configuration and Functions

DGN Package
8-Pin MSOP
Top View
LM3407 30046602.gif

Pin Functions

PIN I/O DESCRIPTION
NO. NAME
1 ISNS I Connect resistor RISNS from this pin to ground for LED current sensing. The current sensing resistor should be placed close to this pin.
2 DIM I PWM Dimming Control Pin. Applying a logic level PWM signal to this pin controls the intended brightness of the LED string.
3 EN I Applying logic high to this pin or leaving it open enables the switcher. When pulled low the switcher is disabled and will enter low power shutdown mode.
4 FS I Switching Frequency Setting Pin. Connect resistor RFS from this pin to ground to set the switching frequency.
5 VIN I Input Voltage Pin. The input voltage should be in the range of 4.5 V to 30 V
6 VCC O Internal Regulator Output Pin. This pin should be bypassed to ground by a ceramic capacitor with a minimum value of 1 µF.
7 GND — This pin should be connected to the system ground.
8 LX O Drain of N-MOSFET Switch. Connect this pin to the output inductor and anode of the Schottky diode.
EP EP — Thermal Pad (Power Ground). Used to dissipate heat from the package during operation. Must be electrically connected to GND external to the package.