SLFS043K August   1983  – January 2026 TLC555 , TLC555M

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  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: VDD = 2V for TLC555C, VDD = 3V for TLC555I
    6. 5.6 Electrical Characteristics: VDD = 5V
    7. 5.7 Electrical Characteristics: VDD = 15V
    8. 5.8 Timing 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 Monostable Operation
      2. 6.3.2 Astable Operation
      3. 6.3.3 Frequency Divider
    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 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 Curves
      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
      5. 7.2.5 Designing for Improved ESD Performance
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.1 Monostable Operation

For monostable operation, Figure 6-2 shows how any of these timers can be connected. If the output is low, application of a negative-going pulse to the trigger (TRIG) sets the internal latch; the output goes high, and discharge pin (DISCH) becomes open drain. Capacitor C then is charged through RA until the voltage across the capacitor reaches the threshold voltage of the threshold (THRES) input. If TRIG has returned to a high level, the output of the threshold comparator resets the internal latch, the output goes low, the discharge pin goes low, which quickly discharges capacitor C.

TLC555 Circuit for Monostable OperationFigure 6-2 Circuit for Monostable Operation

Monostable operation is initiated when TRIG voltage is less than the trigger threshold. If initiated, the sequence ends only if TRIG is high for at least 1µs before the end of the timing interval. When the trigger is grounded, the comparator storage time can be as long as 1µs, which limits the minimum monostable pulse duration to 1µs. The output pulse duration is approximately tw = 1.1 × RAC. Figure 6-4 is a plot of the time constant for various values of RA and C. The threshold levels and charge rates both are directly proportional to the supply voltage, VDD. The timing interval is, therefore, independent of the supply voltage, so long as the supply voltage is constant during the time interval.

Applying a negative-going trigger pulse simultaneously to RESET and TRIG during the timing interval discharges capacitor C and reinitiates the cycle, commencing on the positive edge of the reset pulse. The output is held low as long as the reset pulse is low. To prevent false triggering, when RESET is not asserted low, RESET must be connected to VDD. If the RESET function is required and the pin is driven by external logic or a microcontroller, use a pullup resistor to VDD (such as 10 kΩ) to prevent the RESET pin from floating. If the RESET function is not required, short the RESET pin directly to the VDD pin.

In monostable applications, set the trip point of the trigger input by a voltage applied to CONT. An input voltage between 10% and 80% of the supply voltage, from a resistor divider with at least 500µA bias, provides good results.

TLC555 Typical Monostable Waveforms
RA = 9.1kΩ CL = 0.01µF See Figure 6-2
Figure 6-3 Typical Monostable Waveforms
TLC555 Output Pulse Duration vs Capacitance
 
Figure 6-4 Output Pulse Duration vs Capacitance