ZHCSMS9J September   1973  – February 2025 NA555 , NE555 , SA555 , SE555

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  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
    6. 5.6 Switching Characteristics
    7. 5.7 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 Monostable Operation
      2. 6.3.2 Astable Operation
      3. 6.3.3 Frequency Divider
    4. 6.4 Device Functional Modes
  8. 7 Applications and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Missing-Pulse Detector
        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 Pulse-Width Modulation
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Curve
      3. 7.2.3 Pulse-Position Modulation
        1. 7.2.3.1 Design Requirements
        2. 7.2.3.2 Detailed Design Procedure
        3. 7.2.3.3 Application Curve
      4. 7.2.4 Sequential Timer
        1. 7.2.4.1 Design Requirements
        2. 7.2.4.2 Detailed Design Procedure
        3. 7.2.4.3 Application Curve
    3. 7.3 Power Supply Recommendations
  9. 8 Device and Documentation Support
    1. 8.1 接收文档更新通知
    2. 8.2 支持资源
    3. 8.3 Trademarks
    4. 8.4 静电放电警告
    5. 8.5 术语表
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

封装选项

请参考 PDF 数据表获取器件具体的封装图。

机械数据 (封装 | 引脚)
  • D|8
  • P|8
  • PS|8
  • PW|8
散热焊盘机械数据 (封装 | 引脚)
订购信息

6.3.2 Astable Operation

Figure 6-5 shows that adding a second resistor, RB, to the circuit of Figure 6-2 and connecting the trigger input to the threshold input causes the timer to self-trigger and run as a multivibrator. Capacitor C charges through RA and RB and then discharges through RB only. Therefore, the duty cycle is controlled by the values of RA and RB.

NA555 NE555 SA555 SE555 Circuit for Astable OperationFigure 6-5 Circuit for Astable Operation
NA555 NE555 SA555 SE555 Typical Astable WaveformsFigure 6-6 Typical Astable Waveforms

This astable connection results in capacitor C charging and discharging between the threshold-voltage level (≅ 0.67 × VCC) and the trigger-voltage level (≅ 0.33 × VCC). As in the mono-stable circuit, charge and discharge times (and, therefore, the frequency and duty cycle) are independent of the supply voltage. To reduce distortion, use at maximum frequency of 100kHz or below. If higher-frequency operation is required, consider using the TLC555 LinCMOS™ Timer instead.

Figure 6-6 shows typical waveforms generated during astable operation. The output high-level duration tH and low-level duration tLare calculated as follows:

Equation 1. t H ≅ 0.693 × R A + R B × C
Equation 2. t L ≅ 0.693 × R B × C

Other useful relationships for period, frequency, and driver-referred and waveform-referred duty cycle are calculated as follows:

Equation 3. T = t H + t L ≅ 0.693 × R A + 2 R B × C
Equation 4. f = 1 T ≅ 1.44 R A + 2 R B × C
Equation 5. O u t p u t   d r i v e r   d u t y   c y c l e = t L T ≅ R B R A + 2 R B
Equation 6. O u t p u t   w a v e f o r m   d u t y   c y c l e = t H T ≅ 1 - R B R A + 2 R B = R A + R B R A + 2 R B
NA555 NE555 SA555 SE555 Free-Running Frequency Figure 6-7 Free-Running Frequency