SCASE79A April   2025  – September 2025 TPUL2T323

PRODUCTION DATA  

  1.   1
  2.   2
  3. 1 Features
  4. 2 Applications
  5. 3 Description
  6. 4 Pin Configuration and Functions
  7. 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
    6. 5.6 Timing Characteristics
    7.     14
    8. 5.7 Switching Characteristics
    9. 5.8 Typical Characteristics
  8. 6 Parameter Measurement Information
  9. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Naming Convention
      2. 7.3.2 Retriggerable One-Shot
      3. 7.3.3 Extended RC Timed One-Shot
      4. 7.3.4 Balanced CMOS Push-Pull Outputs
      5. 7.3.5 CMOS Schmitt-Trigger Inputs
      6. 7.3.6 Latching Logic with Known Power-Up State
      7. 7.3.7 Partial Power Down (Ioff)
      8. 7.3.8 Reduced Input Threshold Voltages
      9. 7.3.9 Clamp Diode Structure
    4. 7.4 Device Functional Modes
      1. 7.4.1 Off-State Operation
      2. 7.4.2 Startup Operation
      3. 7.4.3 On-State Operation
  10. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application - Edge Detector
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Timing Components
        2. 8.2.1.2 Input Considerations
        3. 8.2.1.3 Output Considerations
        4. 8.2.1.4 Power Considerations
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Typical Application - Delayed Pulse Generator
      1. 8.3.1 Application Curves
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  11. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  12. 10Revision History
  13. 11Mechanical, Packaging, and Orderable Information

7.3.3 Extended RC Timed One-Shot

The output pulse width (two) is controlled by the selection of external timing components Rext and Cext. The TPUL2T323 has been designed to target a typical output pulse width of two ≅ 1000 × Rext × Cext, however the actual pulse width changes with multiple variables, and thus a nonlinearity correction factor, K, is added to provide the system designer with a more accurate pulse width estimation. Equation 1 is used to most accurately predict the output pulse width.

Equation 1. t wo = K × 1024 × R e x t × C e x t

The output pulse width is dependent on multiple variables:

  • External timing components (Rext, Cext)
  • Voltage
  • Temperature
  • Manufacturing and design
  • Digital state machine operation

The external timing component values directly control the output pulse width, and any variations in component values due to manufacturing, voltage, or temperature will directly impact the output pulse width.

Most resistors maintain very consistent values during operation, and thus tend to have little impact on accuracy.

Most capacitors have a wide variation of manufacturing values, and additionally can vary due to temperature and operating voltage. Typically, the timing capacitor is the largest single source of error for RC timed monostable multivibrators.

There is also some error introduced by the TPUL2T323. This error is provided as Δtwo in the Switching Characteristics section and includes variations due to digital state machine operation, design, manufacturing, and temperature. There is additionally some randomness inherent to the pulse width even with all other factors held constant which is typically less than 1% and is accounted for in the Δtwo specification.

Estimating the percent error of the output pulse width (eΔtwo) requires multiple inputs. Equation 2 provides the best method to estimate total pulse width error due to tolerance of components, with eR being the error introduced by the timing resistor, eC being the error introduced by the timing capacitor, and Δtwo being the error introduced by the TPUL2T323.

Equation 2. e Δ t w o = e R + e C + e R e C + Δ t w o 1 + e R + e C + e R e C

For a quick estimate, the sum of the error values can be used (eΔtwo ≅ eR + eC + Δtwo). For example, a typical TPUL2T323 application circuit using an X7R capacitor (5% manufacturing tolerance + 15% temperature variation), 0.1% resistor, and Δtwo of 5% would have a quickly estimated maximum error of 25.1%. With the more accurate equation, the maximum error is actually 26.126%.