SNVS699I February   2011  – May 2026 LM5045

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  High-Voltage Start-Up Regulator
      2. 6.3.2  Line Undervoltage Detector
      3. 6.3.3  Overvoltage Protection
      4. 6.3.4  Reference
      5. 6.3.5  Oscillator, Sync Input
      6. 6.3.6  Cycle-by-Cycle Current Limit
      7. 6.3.7  Hiccup Mode
      8. 6.3.8  PWM Comparator
      9. 6.3.9  Ramp Pin
      10. 6.3.10 Slope Pin
      11. 6.3.11 Soft-Start
      12. 6.3.12 Gate Driver Outputs
      13. 6.3.13 Synchronous Rectifier Control Outputs (SR1 and SR2)
      14. 6.3.14 Soft-Start of the Synchronous Rectifiers
      15. 6.3.15 Prebias Startup
      16. 6.3.16 Soft-Stop
      17. 6.3.17 Soft-Stop Off
      18. 6.3.18 Thermal Protection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Control Method Selection
      2. 6.4.2 Voltage Mode Control Using the LM5045
      3. 6.4.3 Current Mode Control Using the LM5045
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 VIN and VCC
        2. 7.2.2.2 For Applications With > 100 VIN
        3. 7.2.2.3 UVLO and OVP Voltage Divider Selection
        4. 7.2.2.4 Current Sense
        5. 7.2.2.5 Hiccup Mode Current Limit Restart
        6. 7.2.2.6 Augmenting the Gate Drive Strength
      3. 7.2.3 Application Curve
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.17 Soft-Stop Off

The Soft-Start Off (SSOFF) pin gives additional flexibility by allowing the power converter to be configured for hard-stop during line UVLO and hiccup mode condition. If the SS OFF pin is pulled up to the 5-V REF pin, the power converter hard-stops in any fault condition. Hard-stop drives each control output to a low state immediately. Refer to Table 6-1 for more details.

LM5045 Stop-Stop Waveforms During a UVLO EventFigure 6-7 Stop-Stop Waveforms During a UVLO Event
Table 6-1 Soft-Stop in Fault Conditions
FAULT CONDITION(1)SSSR
UVLO
(UVLO<1.25V)		Soft-Stop
3x the charging rate
OVP
(OVP>1.25V)		Hard-Stop
Hiccup
(CS>0.75 and RES>1V)		Soft-Stop
6x the charging rate
VCC/VREF UVHard-Stop
Internal Thermal LimitHard-Stop
(1) Note: All the above conditions are valid with SSOFF pin tied to GND. If SSOFF=5V, the LM5045 hard-stops in all the conditions. The SS pin remains high in all the conditions until the SSSR pin reaches 1V.