SGLS187C September   2003  – August 2025 UCC2808A-1EP , UCC2808A-2EP

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Pin Descriptions
        1. 7.3.1.1 COMP
        2. 7.3.1.2 CS
        3. 7.3.1.3 FB
        4. 7.3.1.4 GND
        5. 7.3.1.5 OUTA and OUTB
        6. 7.3.1.6 RC
        7. 7.3.1.7 VDD
    4. 7.4 Device Functional Modes
      1. 7.4.1 VCC
      2. 7.4.2 Push-Pull or Half-Bridge Function
  9. 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
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • D|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1 Application Information

Figure 8-1 shows a 200kHz push-pull application circuit with a full-wave rectifier. The output, VO, provides 5V at 50W maximum and is electrically isolated from the input. Because the UCC2808A-xEP is a peak-current-mode controller, the 2N2907 emitter following amplifier (buffers the CT waveform) provides slope compensation that is necessary for duty ratios greater than 50%. Capacitor decoupling is very important with a single-ground IC controller. TI recommends using a 1μF capacitor that is placed as close to the IC as possible. The controller supply is a series RC for start-up, paralleled with a bias winding on the output inductor used in steady-state operation.

Isolation is provided by an optocoupler with regulation done on the secondary side using the TL431 adjustable precision shunt regulator. Small-signal compensation with tight voltage regulation is achieved using this part on the secondary side. Many choices exist for the output inductor depending on cost, volume, and mechanical strength. Several design options are iron powder, molypermalloy (MPP), or a ferrite core with an air gap as shown here. The main power transformer has a Magnetics Inc. ER28-size core made of P material for efficient operation at this frequency and temperature. The input voltage ranges from 36Vdc to 72Vdc.