ZHCSMS9J September 1973 – February 2025 NA555 , NE555 , SA555 , SE555
PRODUCTION DATA
- 1
- 1 特性
- 2 應(yīng)用
- 3 說明
- 4 Pin Configuration and Functions
- 5 Specifications
- 6 Detailed Description
- 7 Applications and Implementation
- 8 Device and Documentation Support
- 9 Revision History
- 10Mechanical, Packaging, and Orderable Information
封裝選項
請參考 PDF 數(shù)據(jù)表獲取器件具體的封裝圖。
機械數(shù)據(jù) (封裝 | 引腳)
- D|8
- P|8
- PS|8
- PW|8
散熱焊盤機械數(shù)據(jù) (封裝 | 引腳)
- PS|8
訂購信息
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.
Figure 6-5 Circuit for Astable Operation
Figure 6-6 Typical Astable WaveformsThis 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:
Other useful relationships for period, frequency, and driver-referred and waveform-referred duty cycle are calculated as follows:
Figure 6-7 Free-Running Frequency