SNVS797B March   2012  – October 2015 LM3492HC , LM3492HC-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Switching Frequency
      2. 8.3.2  LDO Regulator
      3. 8.3.3  Enable and Disable
      4. 8.3.4  Current Limit
      5. 8.3.5  Thermal Protection
      6. 8.3.6  Dynamic Headroom Control, Over-Ride, and Soft-Start
      7. 8.3.7  Current Regulator
      8. 8.3.8  Output Voltage Feedback
      9. 8.3.9  Overvoltage Protection
      10. 8.3.10 Bidirectional Communication Pin
        1. 8.3.10.1 Power-Good Indication
        2. 8.3.10.2 Overtemperature Indication
        3. 8.3.10.3 Output Current Undervoltage Indication
        4. 8.3.10.4 Switching Frequency Tuning
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
      1. 8.5.1 Output Current Overvoltage Indication
      2. 8.5.2 COMM Pin Bit Pattern
      3. 8.5.3 Channel 1 Disable
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
        1. 9.2.1.1 RFB1, RFB2, and CFB
        2. 9.2.1.2 L1
        3. 9.2.1.3 D1
        4. 9.2.1.4 CIN and COUT
        5. 9.2.1.5 CVCC
        6. 9.2.1.6 CCDHC
        7. 9.2.1.7 RRT and RIREF
        8. 9.2.1.8 RCOMM
      2. 9.2.2 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Boost Converter
    • Automotive Grade Product, Q100 Grade-1 Qualified
    • Very Wide Input Voltage Range: 4.5 V to 65 V
    • Programmable Soft-Start Period
    • No Loop Compensation Required
    • Stable with Ceramic and Other Low ESR Capacitors with No Audible Noise
    • Nearly Constant Switching Frequency Programmable from 200 kHz to 1 MHz
  • Current Regulator
    • Programmable LED Current: 50 mA to 250 mA
    • 10000:1 Contrast Ratio, 300-ns Minimum Pulse Width
    • Two Individual Dimmable LED Strings up to 65 V, Total 15 W (Typically 28 LEDs at 150 mA)
    • Dynamic Headroom Control Maximizes Efficiency
    • Over-Power Protection
    • ±3% Current Accuracy
  • Supervisory Functions
    • Precision Enable
    • COMM I/O Pin for Diagnostic and Commands
    • Thermal Shutdown Protection
    • Thermally Enhanced PWP, 20-Pin Package

2 Applications

  • Ultra-High Contrast Ratio 6.5” to 10” LCD Display Backlight up to 28 LEDs
  • Automotive or Marine GPS Display

3 Description

The LM3492HC/-Q1 device integrates a boost converter and a two-channel current regulator to implement a highly efficient and cost effective LED driver. This device drives two individually dimmable LED strings with a maximum power of 15 W and an output voltage of up to 65 V. The boost converter employs a proprietary projected-on-time control method to give a fast transient response with no compensation required. The nearly constant switching frequency can be set to a level from 200 kHz to 1 MHz. Ceramic capacitors stabilize the application circuit and produce no audible noise on dimming. The programmable peak current limit and soft-start features reduce current surges at start-up. An integrated, 190-mΩ, 3.9-A, N-Channel MOSFET switch minimizes the solution size. The fast slew rate current regulator allows high frequency and narrow pulse width dimming signals to achieve a very high contrast ratio of 10000:1. The LED current can be set from 50 mA to 250 mA by a single resistor.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM3492HC PWP (20) 6.50 mm × 4.40 mm
LM3492HC-Q1
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Application

LM3492HC-Q1 LM3492HC simp_app_snvs797.gif