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

9.3.5 Pulse-Width Modulation (PWM)

The comparator also provides modulation control of the output pulse width. For this, the ramp voltage across timing capacitor CT is compared to the control signal present at the output of the error amplifiers. The timing capacitor input incorporates a series diode that is omitted from the control signal input. This requires the control signal (error amplifier output) to be ∼0.7 V greater than the voltage across CT to inhibit the output logic, and ensures maximum duty cycle operation without requiring the control voltage to sink to a true ground potential. The output pulse width varies from 97% of the period to 0 as the voltage present at the error amplifier output varies from 0.5 V to 3.5 V, respectively.