SLVS074I January   1983  – July 2022 TL494

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Simplified Block Diagram
  5. 5 Revision History
  6. 6 Pin Configuration and Functions
  7. 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, Reference Section
    6. 7.6  Electrical Characteristics, Oscillator Section
    7. 7.7  Electrical Characteristics, Error-Amplifier Section
    8. 7.8  Electrical Characteristics, Output Section
    9. 7.9  Electrical Characteristics, Dead-Time Control Section
    10. 7.10 Electrical Characteristics, PWM Comparator Section
    11. 7.11 Electrical Characteristics, Total Device
    12. 7.12 Switching Characteristics
    13. 7.13 Typical Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 5-V Reference Regulator
      2. 9.3.2 Oscillator
      3. 9.3.3 Dead-time Control
      4. 9.3.4 Comparator
      5. 9.3.5 Pulse-Width Modulation (PWM)
      6. 9.3.6 Error Amplifiers
      7. 9.3.7 Output-Control Input
      8. 9.3.8 Output Transistors
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Input Power Source
        2. 10.2.2.2 Control Circuits
          1. 10.2.2.2.1 Oscillator
          2. 10.2.2.2.2 Error Amplifier
          3. 10.2.2.2.3 Current-Limiting Amplifier
          4. 10.2.2.2.4 Soft Start and Dead Time
        3. 10.2.2.3 Inductor Calculations
        4. 10.2.2.4 Output Capacitance Calculations
        5. 10.2.2.5 Transistor Power-Switch Calculations
      3. 10.2.3 Application Curves for Output Characteristics
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 Feedback Traces
      2. 12.1.2 Input/Output Capacitors
      3. 12.1.3 Compensation Components
      4. 12.1.4 Traces and Ground Planes
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Trademarks
    2. 13.2 Electrostatic Discharge Caution
    3. 13.3 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

The error amplifier compares a sample of the 5-V output to the reference and adjusts the PWM to maintain a constant output current (see Figure 10-3).

GUID-ED7C7FAF-153B-4800-8D18-E266DD289FF1-low.gifFigure 10-3 Error-Amplifier Section

The TL494 internal 5-V reference is divided to 2.5 V by R3 and R4. The output-voltage error signal also is divided to 2.5 V by R8 and R9. If the output must be regulated to exactly 5.0 V, a 10-kΩ potentiometer can be used in place of R8 to provide an adjustment.

To increase the stability of the error-amplifier circuit, the output of the error amplifier is fed back to the inverting input through RT, reducing the gain to 101.