Datasheet LM556-MIL (Texas Instruments) - 8

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LM556-MIL
SNAS746 – JUNE 2017
www.ti.com 7 Detailed Description 7.1 Overview
The LM556-MIL dual-timing circuit is a highly stable device for generating accurate time delays or oscillations. The two timers operate independently from one another, only sharing VCC and ground. For each individual timer, additional terminals are provided for triggering or resetting. In the monostable mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable mode operation as an oscillator, the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms and the output circuit can source or sink up to 200 mA.
7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 Operating Characteristics
The LM556-MIL is specified for operation from 4.5 V to 16 V. Many of the specifications apply from 0⁰C to 70⁰C. Parameters that can exhibit significant variance with regard to operating voltage or temperature are presented in the Electrical Characteristics and Typical Characteristics sections.
7.3.2 Timing from Microseconds Through Hours
The LM556-MIL has the ability to have timing parameters from the microseconds range to hours. The time delay of the system can be determined by the time constant of the R and C values used for either the monostable or astable configuration. A nomograph is available for easy determination of R and C values for various time delays.
7.4 Device Functional Modes
The LM556-MIL can operate in both astable and monostable mode depending on the application requirements.
7.4.1 Monostable Mode
The LM556-MIL timer acts as a one-shot pulse generator. The pulse begins when the LM556-MIL timer receives a signal at the trigger input that falls below 1/3 of the voltage supply. The width of the output pulse is determined by the time constant of an RC network. The output pulse ends when the voltage on the capacitor equals 2/3 of the supply voltage. The output pulse width can be extended or shortened depending on the application by adjusting the R and C values. More details are given in the LM555 datasheet (SNAS548). 8 Submit Documentation Feedback Copyright © 2017, Texas Instruments Incorporated Product Folder Links: LM556-MIL Document Outline 1 Features 2 Applications 3 Description Table of Contents 4 Revision History 5 Pin Configuration and Functions 6 Specifications 6.1 Absolute Maximum Ratings 6.2 ESD Ratings 6.3 Recommended Operating Conditions 6.4 Thermal Information 6.5 Electrical Characteristics 6.6 Typical Characteristics 7 Detailed Description 7.1 Overview 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 Operating Characteristics 7.3.2 Timing from Microseconds Through Hours 7.4 Device Functional Modes 7.4.1 Monostable Mode 7.4.2 Astable (Free-Running) Mode 8 Application and Implementation 8.1 Application Information 8.2 Typical Application 8.2.1 Design Requirements 8.2.2 Detailed Design Procedure 8.2.3 Application Curve 9 Power Supply Recommendations 10 Layout 10.1 Layout Guidelines 10.2 Layout Example 11 Device and Documentation Support 11.1 Documentation Support 11.1.1 Related Documentation 11.2 Receiving Notification of Documentation Updates 11.3 Community Resources 11.4 Trademarks 11.5 Electrostatic Discharge Caution 11.6 Glossary 12 Mechanical, Packaging, and Orderable Information