SNVS682D November   2010  – December 2015 LM3444

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 Theory of Operation
      2. 7.3.2 Valley-Fill Circuit
      3. 7.3.3 Valley-Fill Operation
      4. 7.3.4 Buck Converter
      5. 7.3.5 Overview Of Constant Off-Time Control
      6. 7.3.6 Thermal Shutdown
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Determining Duty-Cycle (D)
      2. 8.1.2  Calculating Off-Time
      3. 8.1.3  Setting the Switching Frequency
      4. 8.1.4  Inductor Selection
      5. 8.1.5  Setting the LED Current
      6. 8.1.6  Valley Fill Capacitors
      7. 8.1.7  Determining the Capacitance Value of the Valley-Fill Capacitors
      8. 8.1.8  Determining Maximum Number of Series Connected LEDs Allowed
      9. 8.1.9  Output Capacitor
      10. 8.1.10 Switching MOSFET
      11. 8.1.11 Recirculating Diode
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
  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 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary

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订购信息

5 Pin Configuration and Functions

DGS Package
10-Pin VSSOP
Top View
LM3444 30127573.gif
D Package
8-Lead SOIC
Top View
LM3444 30127503.gif

Pin Functions

PIN I/O DESCRIPTION
NAME VSSOP SOIC
COFF 4 8 I OFF time setting pin. A user set current and capacitor connected from the output to this pin sets the constant OFF time of the switching controller.
FILTER 5 2 I Filter input. A low pass filter tied to this pin can filter a PWM dimming signal to supply a DC voltage to control the LED current. Can also be used as an analog dimming input. If not used for dimming connect a 0.1-µF capacitor from this pin to ground.
GATE 8 5 O Power MOSFET driver pin. This output provides the gate drive for the power switching MOSFET of the buck controller.
GND 6 3 — Circuit ground connection
ISNS 7 4 I LED current sense pin. Connect a resistor from main switching MOSFET source, ISNS to GND to set the maximum LED current.
NC 1, 2, 3, 10 1, 7 — No internal connection. Leave this pin open.
VCC 9 6 O Input voltage pin. This pin provides the power for the internal control circuitry and gate driver.