SLVS074J January   1983  – September 2026 TL494

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics, Reference Section
    6. 5.6  Electrical Characteristics, Oscillator Section
    7. 5.7  Electrical Characteristics, Error-Amplifier Section
    8. 5.8  Electrical Characteristics, Output Section
    9. 5.9  Electrical Characteristics, Dead-Time Control Section
    10. 5.10 Electrical Characteristics, PWM Comparator Section
    11. 5.11 Electrical Characteristics, Total Device
    12. 5.12 Switching Characteristics
    13. 5.13 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 5V Reference Regulator
      2. 7.3.2 Oscillator
      3. 7.3.3 Dead-time Control
      4. 7.3.4 Comparator
      5. 7.3.5 Pulse-Width Modulation (PWM)
      6. 7.3.6 Error Amplifiers
      7. 7.3.7 Output-Control Input
      8. 7.3.8 Output Transistors
    4. 7.4 Device Functional Modes
  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
        1. 8.2.2.1 Input Power Source
        2. 8.2.2.2 Control Circuits
          1. 8.2.2.2.1 Oscillator
          2. 8.2.2.2.2 Error Amplifier
          3. 8.2.2.2.3 Current-Limiting Amplifier
          4. 8.2.2.2.4 Soft Start and Dead Time
        3. 8.2.2.3 Inductor Calculations
        4. 8.2.2.4 Output Capacitance Calculations
        5. 8.2.2.5 Transistor Power-Switch Calculations
      3. 8.2.3 Application Curves for Output Characteristics
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Feedback Traces
        2. 8.4.1.2 Input/Output Capacitors
        3. 8.4.1.3 Compensation Components
        4. 8.4.1.4 Traces and Ground Planes
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Documentation Support
      1. 9.3.1 Related Documentation
    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

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

8.2.2.4 Output Capacitance Calculations

After calculating the filter inductor, calculate the value of the output filter capacitor to meet the output ripple requirements. Model an electrolytic capacitor as a series connection of an inductance, a resistance, and a capacitance. To provide good filtering, the ripple frequency must be far below the frequencies at which the series inductance becomes important. So, the two components of interest are the capacitance and the effective series resistance (ESR). Calculate the maximum ESR according to the relation between the specified peak-to-peak ripple voltage and the peak-to-peak ripple current.

Equation 19. E S R m a x = Δ V O r i p p l e Δ I L = V 1.5 A ≅ 0.067 Ω

Use Equation 20 to calculate the minimum capacitance of C3 necessary to maintain the VO ripple voltage at less than the 100mV design objective.

Equation 20. C 3 = Δ I L 8 f Δ V O = 1.5 A 8 × 20 × 10 3 × 0.1 V = 94 μ F

A 220mF, 60V capacitor is selected because the 60V capacitor has a maximum ESR of 0.074Ω and a maximum ripple current of 2.8A.