SCLS450H December   1999  – January 2025 SN74LV221A

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Description
  4. 3 Pin Configuration and Functions
  5. 4 Specifications
    1. 4.1  Absolute Maximum Ratings
    2. 4.2  ESD Ratings
    3. 4.3  Recommended Operating Conditions
    4. 4.4  Thermal Information
    5. 4.5  Electrical Characteristics
    6. 4.6  Timing Requirements, VCC = 2.5V ± 0.2V
    7. 4.7  Timing Requirements, VCC = 3.3V ± 0.3V
    8. 4.8  Timing Requirements, VCC = 5V ± 0.5V
    9. 4.9  Switching Characteristics, VCC = 2.5V ± 0.2V
    10. 4.10 Switching Characteristics, VCC = 3.3V ± 0.3V
    11. 4.11 Switching Characteristics, VCC = 5V ± 0.5V
    12. 4.12 Operating Characteristics
    13. 4.13 Input/Output Timing Diagram
  6. 5 Parameter Measurement Information
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Device Functional Modes
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Caution in Use
      2. 7.1.2 Power-down Considerations
      3. 7.1.3 Output Pulse Duration
    2. 7.2 Power Supply Recommendations
    3. 7.3 Layout
      1. 7.3.1 Layout Guidelines
      2. 7.3.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

7.1.3 Output Pulse Duration

The output pulse duration, tw, is determined primarily by the values of the external capacitance (CT) and timing resistance (RT). The timing components are connected as shown in Figure 7-1.

SN74LV221A Timing-Component Connections Figure 7-1 Timing-Component Connections

The pulse duration is given by:

tw + K × RT × CT (1)

if CT is ≥ 1000 pF, K = 1.0

or

if CT is < 1000 pF, K can be determined from Figure 7-6

where:

tw = pulse duration in ns

RT = external timing resistance in kΩ

CT = external capacitance in pF

K = multiplier factor

Equation 1 and Figure 7-2 or Figure 7-3 can be used to determine values for pulse duration, external resistance, and external capacitance.

SN74LV221A Output Pulse Duration vs External Timing Capacitance Figure 7-2 Output Pulse Duration vs External Timing Capacitance
SN74LV221A Output Pulse Duration vs External Timing Capacitance Figure 7-3 Output Pulse Duration vs External Timing Capacitance
SN74LV221A Variation in Output Pulse Duration vs Temperature Figure 7-4 Variation in Output Pulse Duration vs Temperature
SN74LV221A External Capacitance vs Multiplier Factor Figure 7-5 External Capacitance vs Multiplier Factor
SN74LV221A Output Pulse Duration Constant vs Supply Voltage Figure 7-6 Output Pulse Duration Constant vs Supply Voltage
SN74LV221A Distribution of Units vs Output Pulse Duration Figure 7-7 Distribution of Units vs Output Pulse Duration