SLUSC18A September   2014  – March 2015 UCC29950

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1. 5.1 Detailed Pin Descriptions
      1. 5.1.1  VCC
      2. 5.1.2  MD_SEL/PS_ON
      3. 5.1.3  SUFG, SUFS
      4. 5.1.4  GD1, GD2
      5. 5.1.5  GND
      6. 5.1.6  AGND
      7. 5.1.7  LLC_CS
      8. 5.1.8  FB
      9. 5.1.9  PFC_GD
      10. 5.1.10 PFC_CS
      11. 5.1.11 VBULK
      12. 5.1.12 AC1, AC2
      13. 5.1.13 AC_DET
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Storage Conditions
    3. 6.3 ESD Ratings
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical 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  Sense Networks
      2. 7.3.2  Sense Network Fault Detection
      3. 7.3.3  PFC Stage Soft-Start
      4. 7.3.4  AC Line Voltage Sensing
      5. 7.3.5  VBLK Sensing
      6. 7.3.6  AC Input UVLO and Brownout Protection
      7. 7.3.7  Dither
      8. 7.3.8  Active X-Cap Discharge
      9. 7.3.9  LLC Stage Soft Start
      10. 7.3.10 PFC Stage Current Sensing
      11. 7.3.11 Input Power Limit
      12. 7.3.12 PFC Stage Soft Start
      13. 7.3.13 Hybrid PFC Control Loop
      14. 7.3.14 PFC Stage Second Current Limit
      15. 7.3.15 PFC Inductor and Bulk Capacitor Recommendations
      16. 7.3.16 PFC Stage Over Voltage Protection
      17. 7.3.17 LLC Stage Control
      18. 7.3.18 Driver Output Stages and Characteristic
      19. 7.3.19 LLC Stage Dead Time Profile
      20. 7.3.20 LLC Stage Current Sensing
      21. 7.3.21 LLC Three Level Over-Current Protection
      22. 7.3.22 Over-Temperature Protection
      23. 7.3.23 Fault Timer and Control
    4. 7.4 Device Functional Modes
      1. 7.4.1 Mode Selection
      2. 7.4.2 Start-Up in Aux Bias Mode
      3. 7.4.3 Start-Up Operation in Self-Bias Mode
      4. 7.4.4 Bias Rail UVLO
      5. 7.4.5 LLC Stage MOSFET Drive
      6. 7.4.6 Gate Drive Transformer
      7. 7.4.7 Gate Drive Device
      8. 7.4.8 Comparison
  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  LLC Stage
        2. 8.2.2.2  LLC Switching Frequency
        3. 8.2.2.3  LLC Transformer Turns Ratio
        4. 8.2.2.4  LLC Stage Equivalent Load Resistance
        5. 8.2.2.5  LLC Gain Range
        6. 8.2.2.6  Select LN and QE
        7. 8.2.2.7  LLC No-Load Gain
        8. 8.2.2.8  Parameters of the LLC Resonant Circuit
        9. 8.2.2.9  Verify the LLC Resonant Circuit Design
        10. 8.2.2.10 LLC Primary-Side Currents
        11. 8.2.2.11 LLC Secondary-Side Currents
        12. 8.2.2.12 LLC Transformer
        13. 8.2.2.13 LLC Resonant Inductor
        14. 8.2.2.14 Combining the LLC Resonant Inductor and Transformer
        15. 8.2.2.15 LLC Resonant Capacitor
        16. 8.2.2.16 LLC Stage with Split Resonant Capacitor
        17. 8.2.2.17 LLC Primary-Side MOSFETs
        18. 8.2.2.18 LLC Output Rectifier Diodes
        19. 8.2.2.19 LLC Stage Output Capacitors
        20. 8.2.2.20 LLC Stage Over-Current Protection, Current Sense Resistor
        21. 8.2.2.21 Detailed Design Procedure for the PFC stage
        22. 8.2.2.22 PFC Stage Output Current Calculation
        23. 8.2.2.23 Line Current Calculation
        24. 8.2.2.24 Bridge Rectifier
        25. 8.2.2.25 PFC Boost Inductor
        26. 8.2.2.26 PFC Input Capacitor
        27. 8.2.2.27 PFC Stage MOSFET
        28. 8.2.2.28 PFC Boost Diode
        29. 8.2.2.29 Bulk Capacitor
        30. 8.2.2.30 PFC Stage Current Sense Resistor
      3. 8.2.3 Application Curves
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1  GND Pin
      2. 10.1.2  GD1, GD2 Pins
      3. 10.1.3  VCC Pin
      4. 10.1.4  SUFG Pin
      5. 10.1.5  SUFS Pin
      6. 10.1.6  AGND Pin
      7. 10.1.7  MD_SEL/PS_ON Pin
      8. 10.1.8  VBULK Pin
      9. 10.1.9  AC1, AC2 Pins
      10. 10.1.10 LLC_CS
      11. 10.1.11 FB
      12. 10.1.12 PFC_CS
      13. 10.1.13 AC_DET
      14. 10.1.14 PFC_GD
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9 Power Supply Recommendations

The UCC29950 should be operated from a VCC rail which is within the limits given in the VCC Bias Supply section of the Electrical Characteristics table. To avoid the possibility that the device might stop switching, VCC must not be allowed to fall into the UVLO range. In order to minimize power dissipation in the device, VCC should not be unnecessarily high. Keeping VCC at 12 V is a good compromise between these competing constraints. The gate drive outputs from the UCC29950 deliver large current pulses into their loads. This indicates the need for a low ESR decoupling capacitor to be connected as directly as possible between the VCC and PGND terminals. Ceramic capacitors with a stable dielectric characteristic over temperature, such as X7R, are recommended. Avoid capacitors which have a large drop in capacitance with applied DC voltage bias and use a part that has a low voltage co-efficient of capacitance. The recommended decoupling capacitance is 10 µF, X7R, with at least a 25-V rating.

Operation in Self Bias Mode requires an additional, larger, energy storage capacitor. The value required depends on the details of the application but typically this part is between 100 µF and 300 µF. This energy storage capacitor does not require low ESR and it does not need to be placed close to the UCC29950. A 25-V rated aluminum electrolytic capacitor is a good choice.