SLUS458G July   2000  – January 2017 UCC28C40 , UCC28C41 , UCC28C42 , UCC28C43 , UCC28C44 , UCC28C45 , UCC38C40 , UCC38C41 , UCC38C42 , UCC38C43 , UCC38C44 , UCC38C45

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Table
  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  Detailed Pin Description
        1. 8.3.1.1 COMP
        2. 8.3.1.2 FB
        3. 8.3.1.3 CS
        4. 8.3.1.4 RT/CT
        5. 8.3.1.5 GND
        6. 8.3.1.6 OUT
        7. 8.3.1.7 VDD
        8. 8.3.1.8 VREF
      2. 8.3.2  Undervoltage Lockout
      3. 8.3.3  ±1% Internal Reference Voltage
      4. 8.3.4  Current Sense and Overcurrent Limit
      5. 8.3.5  Reduced-Discharge Current Variation
      6. 8.3.6  Oscillator Synchronization
      7. 8.3.7  Soft Start
      8. 8.3.8  Enable and Disable
      9. 8.3.9  Slope Compensation
      10. 8.3.10 Voltage Mode
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation
      2. 8.4.2 UVLO Mode
  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. 9.2.2.1  Input Bulk Capacitor and Minimum Bulk Voltage
        2. 9.2.2.2  Transformer Turns Ratio and Maximum Duty Cycle
        3. 9.2.2.3  Transformer Inductance and Peak Currents
        4. 9.2.2.4  Output Capacitor
        5. 9.2.2.5  Current Sensing Network
        6. 9.2.2.6  Gate Drive Resistor
        7. 9.2.2.7  VREF Capacitor
        8. 9.2.2.8  RT/CT
        9. 9.2.2.9  Start-Up Circuit
        10. 9.2.2.10 Voltage Feedback Compensation
          1. 9.2.2.10.1 Power Stage Poles and Zeroes
          2. 9.2.2.10.2 Slope Compensation
          3. 9.2.2.10.3 Open-Loop Gain
          4. 9.2.2.10.4 Compensation Loop
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Precautions
      2. 11.1.2 Feedback Traces
      3. 11.1.3 Bypass Capacitors
      4. 11.1.4 Compensation Components
      5. 11.1.5 Traces and Ground Planes
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

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

Features

  • Enhanced Replacement for UCx84x and UCx84xA Family With Pin-to-Pin Compatibility
  • 1-MHz Operation
  • 50-µA Standby Current, 100-µA Maximum
  • Low Operating Current of 2.3 mA at 52 kHz
  • Fast 35-ns Cycle-by-Cycle Over-Current Limiting
  • ±1-A Peak Output Current
  • Rail-to-Rail Output Swings with 25-ns Rise and 20-ns Fall Times
  • ±1% Initial Trimmed 2.5-V Error Amplifier Reference
  • Trimmed Oscillator Discharge Current
  • New Undervoltage Lockout Versions
  • VSSOP-8 Package Minimizes Board Space

Applications

  • Switch-Mode Power Supplies
  • General Purpose DC-DC or Off-Line Isolated Power Converters
  • Board Mount Power Modules

Description

UCCx8C4x family are high-performance, current-mode PWM controllers. The UCCx8C4x is an enhanced BiCMOS version with pin-for-pin compatibility to the industry standard UCx84xA family and UCx84x family of PWM controllers. The BiCMOS technology offers lower power consumption to improve efficiency as well as faster current sense and oscillator frequency. In addition, lower startup voltage versions of 7 V are offered as UCCx8C40 and UCCx8C41 for use in battery systems. The UCC28C4x series is specified for operation from –40°C to 105°C, and the UCC38C4x series is specified for operation from 0°C to 70°C.

Providing necessary features to control fixed frequency, peak current-mode power supplies, this family offers the following performance advantages. The device offers high-frequency operation up to 1 MHz, suitable for high speed applications. The trimmed discharge current enables more precise programming of the maximum duty cycle and dead-time limit when compared to the UCx84x family. Reduced start-up and operating currents minimizes start-up loss and low operating power consumption for improved efficiency. The device also features a fast current-sense-to-output delay time of 35 ns for superior overload protection at the power switch, and a ±1-A peak output current capability with improved rise and fall times for driving large external MOSFETs directly.

The UCC38C4x family is offered in 8-pin VSSOP (DGK), 8-pin SOIC (D), and 8-pin PDIP (P) packages.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
UCC28C4x, UCC38C4x SOIC (8) 3.91 mm × 4.90 mm
PDIP (8) 6.35 mm × 9.81 mm
VSSOP (8) 3.00 mm × 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

UCC28C40 UCC28C41 UCC28C42 UCC28C43 UCC28C44 UCC28C45 UCC38C40 UCC38C41 UCC38C42 UCC38C43 UCC38C44 UCC38C45 simplified_app_slus458.gif