SLLS654E April   2005  – November 2025 MC33063A-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     Pin 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 Oscillator Characteristics
    6. 5.6 Output Switch Characteristics
    7. 5.7 Comparator Characteristics
    8. 5.8 Total Device Characteristics
    9. 5.9 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Reference Voltage
      2. 6.3.2 Current Limit
      3. 6.3.3 Current Limit of Typical Operation Waveforms
    4. 6.4 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Step-Up Converter
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Curve
      2. 7.2.2 Step-Down Converter
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curves
      3. 7.2.3 Voltage Inverter Converter
        1. 7.2.3.1 Design Requirements
        2. 7.2.3.2 Detailed Design Procedure
        3. 7.2.3.3 Application Curves
      4. 7.2.4 12V Battery Based Automotive Supply
        1. 7.2.4.1 Design Requirements
        2. 7.2.4.2 Detailed Design Procedure
        3. 7.2.4.3 Application Curve
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Trademarks
    2. 10.2 Electrostatic Discharge Caution
    3. 10.3 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.2 Current Limit

Current limit is accomplished by monitoring the voltage drop across an external sense resistor located in series with VCC and the output switch. The voltage drop developed across the sense resistor is monitored by the current-sense pin, Ipk. When the voltage drop across the sense resistor becomes greater than the preset value of 330mV, the current-limit circuitry provides an additional current path to charge the timing capacitor (CT) rapidly, to reach the upper oscillator threshold and, thus, limiting the amount of energy stored in the inductor. The minimum sense resistor is 0.2W. Figure 6-2 shows the timing capacitor charge current versus current-limit sense voltage. To set the peak current, Ipk = 330mV/Rsense.

MC33063A-Q1 Timing Capacitor Charge Current vs Current-Limit Sense VoltageFigure 6-2 Timing Capacitor Charge Current vs Current-Limit Sense Voltage