BETAPIN 1 · Ground
Supply returnGND
Function
Common reference for the timer.
How to connect
Connect to circuit ground.
Low-power CMOS timer
TLC555 Pinout
Explore TLC555 pins, signal names, electrical functions and connection guidance for each package.
Package view
8Physical pins
TLC555CPPDIP-8
Manufacturer-referencedTexas Instruments
Pin diagram
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TLC555CPPDIP-8Top view
TLC555CDRSOIC-8Top view
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PIN 2 · Timing inputs
Trigger inputTRIG
Function
Below approximately one-third VDD sets the latch when RESET is inactive.
How to connect
Join THRES6 at the timing capacitor node.
Electrical note
A sustained LOW trigger can hold the output HIGH.
PIN 3 · Output and discharge
CMOS outputOUT
Function
Push-pull timing output.
How to connect
Drive an LED through 4.7 kΩ to ground.
Electrical note
Output voltage depends on load. Source capability is lower than sink capability.
PIN 4 · Reset and control
Active-LOW resetRESET
Function
Overrides the comparators, forcing OUT LOW and DISCH conducting.
How to connect
Tie to VDD for continuous oscillation.
Electrical note
Never leave RESET floating.
PIN 5 · Reset and control
Comparator referenceCONT
Function
Approximately two-thirds VDD with no external drive.
How to connect
Bypass to ground with 10 nF.
Electrical note
Changing CONT changes timing thresholds and equations.
PIN 6 · Timing inputs
Threshold inputTHRES
Function
Above CONT resets the latch when TRIG is above its lower threshold.
How to connect
Join TRIG2 at the timing capacitor node.
PIN 7 · Output and discharge
Discharge switchDISCH
Function
Provides a low-impedance path to ground while OUT is LOW.
How to connect
Connect to the RA/RB junction.
Electrical note
Not a second push-pull output.
PIN 8 · Supply
Positive supplyVDD
Function
Power for the CMOS timer.
How to connect
Apply +5 V; bypass to GND1 locally with 100 nF.
Electrical note
Selected TLC555C grade: recommended 2–15 V, 0–70°C.