SNVSB14C April   2018  – October 2021 LM5036

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 Switching Characteristics
    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  High-Voltage Start-Up Regulator
      2. 7.3.2  Undervoltage Lockout (UVLO)
      3. 7.3.3  Reference Regulator
      4. 7.3.4  Oscillator, Synchronized Input
      5. 7.3.5  Voltage-Mode Control
      6. 7.3.6  Primary-Side Gate Driver Outputs (LSG and HSG)
      7. 7.3.7  Half-Bridge PWM Scheme
      8. 7.3.8  Maximum Duty Cycle Operation
      9. 7.3.9  Pre-Biased Start-Up Process
        1. 7.3.9.1 Primary FETs Soft-Start Process
        2. 7.3.9.2 Synchronous Rectifier (SR) Soft-Start Process
      10. 7.3.10 Zero Duty Cycle Operation
      11. 7.3.11 Enhanced Cycle-by-Cycle Current Limiting with Pulse Matching
      12. 7.3.12 Reverse Current Protection
      13. 7.3.13 CBC Threshold Accuracy
      14. 7.3.14 Hiccup Mode Protection
      15. 7.3.15 Hiccup Mode Blanking
      16. 7.3.16 Over-Temperature Protection (OTP)
      17. 7.3.17 Over-Voltage / Latch (ON_OFF Pin)
      18. 7.3.18 Auxiliary Constant On-Time Control
      19. 7.3.19 Auxiliary On-Time Generator
      20. 7.3.20 Auxiliary Supply Current Limiting
      21. 7.3.21 Auxiliary Primary Output Capacitor Ripple
      22. 7.3.22 Auxiliary Ripple Configuration and Control
      23. 7.3.23 Asynchronous Mode Operation of Auxiliary Supply
    4. 7.4 Device Functional Modes
  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  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Input Transient Protection
        3. 8.2.2.3  Level-Shift Detection Circuit
        4. 8.2.2.4  Applications with VIN > 100-V
        5. 8.2.2.5  Applications without Pre-Biased Start-Up Requirement
        6. 8.2.2.6  UVLO Voltage Divider Selection
        7. 8.2.2.7  Over Voltage, Latch (ON_OFF Pin) Voltage Divider Selection
        8. 8.2.2.8  SS Capacitor
        9. 8.2.2.9  SSSR Capacitor
        10. 8.2.2.10 Half-Bridge Power Stage Design
        11. 8.2.2.11 Current Limit
        12. 8.2.2.12 Auxiliary Transformer
        13. 8.2.2.13 Auxiliary Feedback Resistors
        14. 8.2.2.14 RON Resistor
        15. 8.2.2.15 VIN Pin Capacitor
        16. 8.2.2.16 Auxiliary Primary Output Capacitor
        17. 8.2.2.17 Auxiliary Secondary Output Capacitor
        18. 8.2.2.18 Auxiliary Feedback Ripple Circuit
        19. 8.2.2.19 Auxiliary Secondary Diode
        20. 8.2.2.20 VCC Diode
        21. 8.2.2.21 Opto-Coupler Interface
        22. 8.2.2.22 Full-Bridge Converter Applications
      3. 8.2.3 Application Curves
  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 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
        1. 11.2.1.1 Receiving Notification of Documentation Updates
    3. 11.3 Support 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

7.3.2 Undervoltage Lockout (UVLO)

The LM5036 controller contains a three-level under-voltage lockout circuit. When the UVLO pin voltage is below VSD (0.38-V typical), the controller is in a low current shutdown mode where the functional circuit blocks are not enabled including VCC startup regulator, auxiliary supply and the main half-bridge control logic and gate drive circuitry, etc.

When UVLO pin voltage is above VSD, the VCC and REF regulators become active.

When the VCC and REF outputs exceed their respective UV thresholds and the input voltage VIN rises above VAUX_UVLO (15-V typical), the auxiliary supply is enabled.

When UVLO pin voltage rises above VUVLO (1.25-V typical) and VCC and REF voltage are above their respective UV thresholds, the control logic of the main half-bridge converter is enabled. The soft-start capacitor is released and normal operation begins. An external set-point voltage divider from VIN to GND can be used to set the minimum operating voltage of the half-bridge converter. The divider must be designed such that the voltage at the UVLO pin is greater than VUVLO when VIN enters the desired operating range. UVLO hysteresis is accomplished with an internal current sink IUVLO (20-µA typical) that is switched on or off into the impedance of the external set-point divider. When the UVLO pin voltage threshold of VUVLO is exceeded, the current sink is deactivated to quickly raise the voltage at the UVLO pin. When the UVLO pin voltage falls below the VUVLO threshold, the current sink is enabled causing the voltage at the UVLO pin to quickly fall. See Table 7-1 for more detail on functional modes of LM5036.