8 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

The LMC555 timer can be used a various configurations, but the most commonly used configuration is in

monostable mode. A typical application for the LMC555 timer in monostable mode is to turn on an LED for a

specific time duration. A pushbutton is used as the trigger to output a high pulse when trigger pin is pulsed low.

This simple application can be modified to fit any application requirement.

8.2 Typical Applications

8.2.1 Flash LED in Monostable Mode

Figure 8-1 shows the schematic of an LMC555 that flashes an LED in monostable mode.

Figure 8-1. Schematic of Monostable Mode to Flash an LED

8.2.1.1 Design Requirements

The main design requirement for this application requires calculating the duration of time that the output stays

high. The duration of time depends on the R and C values (shown in Figure 7-4) and is calculated by the

following equation:

t = 1.1 × R × C seconds

(6)

LMC555

SNAS558N – JANUARY 2000 – REVISED MARCH 2024

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