SLUSBQ5D November   2013  – July 2016 UCC28180


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Description (Continued)
  6. Pin Configuration and Functions
  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. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Soft Start
      2. 8.3.2  System Protection
      3. 8.3.3  VCC Undervoltage LockOut (UVLO)
      4. 8.3.4  Output Overvoltage Protection (OVP)
      5. 8.3.5  Open Loop Protection/Standby (OLP/Standby)
      6. 8.3.6  ISENSE Open-Pin Protection (ISOP)
      7. 8.3.7  ICOMP Open-Pin Protection (ICOMPP)
      8. 8.3.8  FAULT Protection
      9. 8.3.9  Output Overvoltage Detection (OVD), Undervoltage Detection (UVD) and Enhanced Dynamic Response (EDR)
      10. 8.3.10 Overcurrent Protection
      11. 8.3.11 Soft Overcurrent (SOC)
      12. 8.3.12 Peak Current Limit (PCL)
      13. 8.3.13 Current Sense Resistor, RISENSE
      14. 8.3.14 ISENSE Pin
      15. 8.3.15 Gate Driver
      16. 8.3.16 Current Loop
      17. 8.3.17 ISENSE and ICOMP Functions
      18. 8.3.18 Pulse Width Modulator
      19. 8.3.19 Control Logic
      20. 8.3.20 Voltage Loop
      21. 8.3.21 Output Sensing
      22. 8.3.22 Voltage Error Amplifier
      23. 8.3.23 Non-Linear Gain Generation
    4. 8.4 Device Functional Modes
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1.  Current Calculations
        2.  Switching Frequency
        3.  Bridge Rectifier
        4.  Inductor Ripple Current
        5.  Input Capacitor
        6.  Boost Inductor
        7.  Boost Diode
        8.  Switching Element
        9.  Sense Resistor
        10. Output Capacitor
        11. Output Voltage Set Point
        12. Loop Compensation
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 Bias Supply
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support . .
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

10 Power Supply Recommendations

10.1 Bias Supply

The UCC28180 operates from an external bias supply. It is recommended that the device be powered from a regulated auxiliary supply. (This device is not intended to be used from a bootstrap bias supply. A bootstrap bias supply is fed from the input high voltage through a resistor with sufficient capacitance on VCC to hold up the voltage on VCC until current can be supplied from a bias winding on the boost inductor. For that reason, the minimal hysteresis on VCC would require an unreasonable value of hold-up capacitance.)

During normal operation, when the output is regulated, current drawn by the device includes the nominal run current plus the current supplied to the gate of the external boost switch. Decoupling of the bias supply must take switching current into account in order to keep ripple voltage on VCC to a minimum. A ceramic capacitor of 0.1-µF minimum value from VCC to GND with short, wide traces is recommended.

UCC28180 supplystate_lusbq5.gif Figure 40. Device Supply States

The device's bias operates in several states. During startup, VCC Under-Voltage LockOut (UVLO) sets the minimum operational DC input voltage of the controller. There are two UVLO thresholds. When the UVLO turn-on threshold is exceeded, the PFC controller turns ON. If the VCC voltage falls below the UVLO turn-off threshold, the PFC controller turns off. During UVLO, current drawn by the device is minimal. After the device turns on, Soft Start (SS) is initiated and the boost inductor current is ramped up in a controlled manner to reduce the stress on the external components and avoids output voltage overshoot. During soft start and after the output is in regulation, the device draws its normal run current. If any of several fault conditions are encountered or if the device is put in standby with an external signal, the device draws a reduced standby current.