SLUSD37E October   2017  – November 2019 UCC28056


  1. Features
  2. Applications
  3. Description
    1.     No Load Power
      1.      Device Images
        1.       Simplified Application
  4. Revision History
  5. Device Comparison Tables
  6. Pin Configuration and Functions
    1.     Pin 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 CrM/DCM Control Principle
      2. 8.3.2 Line Voltage Feed-Forward
        1. Peak Line Voltage Detection
      3. 8.3.3 Valley Switching and CrM/DCM Hysteresis
        1. Valley Delay Adjustment
      4. 8.3.4 Transconductance Amplifier with Transient Speed-up Function
      5. 8.3.5 Faults and Protections
        1. Supply Undervoltage Lockout
        2. Two Level Over-Current Protection
          1. Cycle-by-Cycle Current Limit Ocp1
          2. Ocp2 Gross Over-Current or CCM Protection
        3. Output Over-Voltage Protection
          1. First Level Output Over-Voltage Protection (Ovp1)
          2. Second Level Over-Voltage Protection (Ovp2)
        4. Thermal Shutdown Protection
        5. Line Under-Voltage or Brown-In
      6. 8.3.6 High-Current Driver
    4. 8.4 Controller Functional Modes
      1. 8.4.1 Burst Mode Operation
      2. 8.4.2 Soft Start
  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. Custom Design With WEBENCH® Tools
        2. Power Stage Design
          1. Boost Inductor Design
          2. Boost Switch Selection
          3. Boost Diode Selection
          4. Output Capacitor Selection
        3. ZCD/CS Pin
          1. Voltage Spikes on the ZCD/CS pin Waveform
        4. VOSNS Pin
        5. Voltage Loop Compensation
          1. Plant Model
          2. Compensator Design
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 VOSNS Pin
      2. 11.1.2 ZCD/CS Pin
      3. 11.1.3 VCC Pin
      4. 11.1.4 GND Pin
      5. 11.1.5 DRV Pin
      6. 11.1.6 COMP Pin
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Custom Design With WEBENCH® Tools
    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

Pin Configuration and Functions

DBV Package
6-Pin SOT-23
Top View
UCC28056 pinout_sot23_slusd37.gif

Pin Functions

COMP 6 I/O Output of the internal transconductance error amplifier and power demand input. To achieve compensation of the voltage loop, connect a suitable RC network from this pin to GND. The error amplifier output is internally limited to VCOClmp. An internal resistor, RCODisch, discharges the external compensation network when the controller is in its Stopb state or when the Ovp2 comparator is tripped. Switching stops, and the controller enters a low-power state (BstOffb), when the voltage on the COMP pin drops below VBSTFall. Switching resumes when the COMP pin voltage exceeds VBSTRise.
DRV 5 I/O GATE connection to drive the main power MOSFET. This output is internally limited to VDRHigh. This is done to reduce power dissipation in the internal driver and allow controller operation from high VCC voltages. An external resistor connected from DRV to GND adjusts the delay between the Drain waveform falling below VIn and the DRV rising edge, allowing the turn on transition to be aligned to the valley minimum accurately over a wide range of idle ring oscillating frequency.
GND 4 G Controller Ground reference pin. Connect to the power stage at the lower terminal of the current sense resistor, RCS, only.
VCC 3 P Positive supply voltage. Switching operation can start once VCC exceeds VCCStart. Switching operation ceases if VCC drops below VCCStop for longer than TUVLOBlk.
ZCD/CS 2 I This pin is fed by a potential divider connected across the Drain & Source pins of the power MOSFET switch. While the DRV pin is high this pin monitors the voltage across the current sense resistor, RCS. This pin implement over-current protection functions. While the DRV pin in low this pin monitors the Drain voltage waveform. Input voltage applied to the power stage can be obtained by filtering the Drain waveform. Input voltage provides Line voltage feed - forward and Line Brown - In features. Drain voltage waveform is also used to provide ZCD detection, valley synchronization and second level output over - voltage protection features.
VOSNS 1 I Voltage error amplifier inverting input. The error amplifier non - inverting input connects to internal reference voltage VOSReg. Error amplifier gain increases with error magnitude to improve transient response without compromising Line current distortion. Output over-voltage protection is implemented on this pin. Switching operation halts if the voltage on this pin exceeds VOvp1Rise and resumes when it drops below VOvp1Fall.