SLUS646K November   2005  – August 2015 UCC28600


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 Terminal Components
    3. 7.3 Feature Description
      1. 7.3.1 Oscillator
      2. 7.3.2 Status
      3. 7.3.3 Fault Logic
      4. 7.3.4 Protection Features
      5. 7.3.5 Overtemperature
      6. 7.3.6 Cycle-by-Cycle Power Limit
      7. 7.3.7 Primary Current Protection
      8. 7.3.8 Over-Voltage Protection
      9. 7.3.9 Undervoltage Lockout
    4. 7.4 Device Functional Modes
      1. 7.4.1 Quasi-Resonant and DCM Control
      2. 7.4.2 Frequency Foldback Mode Control
      3. 7.4.3 Green-Mode Control
      4. 7.4.4 Operating Mode Programming
  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. Input Bulk Capacitor and Minimum Bulk Voltage
        2. Transformer Turns Ratio and Primary Inductance
        3. Non-Ideal Current Sense Value
        4. Snubber Damping
        5. Open Loop Test Circuit
      3. 8.2.3 Application Curves
    3. 8.3 Do's and Don'ts
  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 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
      2. 11.2.2 Related Products
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, 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

5 Pin Configuration and Functions

D Package
8-Pin SOIC
Top View
UCC28600 pin_lus646.gif

Pin Functions

CS 3 I Current sense input. Also programs power limit, and used to control modulation and activate overcurrent protection. The CS voltage input originates across a current sense resistor and ground. Power limit is programmed with an effective series resistance between this pin and the current sense resistor.
FB 2 I Feedback input or control input from the optocoupler to the PWM comparator used to control the peak current in the power MOSFET. An internal 20-kΩ resistor is between this pin and the internal 5-V regulated voltage. Connect the collector of the photo-transistor of the feedback optocoupler directly to this pin; connect the emitter of the photo-transistor to GND. The voltage of this pin controls the mode of operation in one of the three modes: quasi resonant (QR), frequency foldback mode (FFM) and green mode (GM).
GND 4 Ground for internal circuitry. Connect a ceramic 0.1-μF bypass capacitor between VDD and GND, with the capacitor as close to these two pins as possible.
OUT 5 O 1-A sink (TrueDrive™ ) and 0.75-A source gate drive output. This output drives the power MOSFET and switches between GND and the lower of VDD or the 13-V internal output clamp.
OVP 7 I Over voltage protection (OVP) input senses line-OVP, load-OVP and the resonant trough for QR turn-on. Detect line, load and resonant conditions using the primary bias winding of the transformer, adjust sensitivity with resistors connected to this pin.
SS 1 I Soft-start programming pin. Program the soft-start rate with a capacitor to ground; the rate is determined by the capacitance and the internal soft-start charge current. The soft-start capacitor should be placed as close as possible to the SS pin and GND, keeping trace length to a minimum. All faults discharge the SS pin to GND through an internal MOSFET with an RDS(on) of approximately 100 Ω. The internal modulator comparator reacts to the lowest of the SS voltage, the internal FB voltage and the peak current limit.
STATUS 8 O ACTIVE HIGH open drain signal that indicates the device has entered standby mode. This pin can be used to disable the PFC control circuit (high impedance = green mode). STATUS pin is high during UVLO, (VDD < start-up threshold), and softstart, (SS < FB).
VDD 6 I Provides power to the device. Use a ceramic 0.1-μF by-pass capacitor for high-frequency filtering of the VDD pin, as described in the GND pin description. Operating energy is usually delivered from auxiliary winding. To prevent hiccup operation during start-up, a larger energy storage cap is also needed between VDD and GND.