BETAPIN 1 · Ground
GroundGND
Function
Circuit reference.
How to connect
Connect to supply return.
Bipolar timer
NE555 Pinout
Explore NE555 pins, signal names, electrical functions and connection guidance for each package.
Package view
8Physical pins
NE555PPDIP-8
Manufacturer-referencedTexas Instruments
Pin diagram
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NE555PPDIP-8Top view
NE555DSOIC-8Top view · dot marks pin 1
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PIN 2 · Timing inputs
InputTRIG
Function
Starts a timing cycle below roughly VCC/3.
How to connect
For astable operation, join TRIG to THRES at the capacitor node.
PIN 3 · Outputs
OutputOUT
Function
Timer output.
How to connect
Drive the LED through a current-limiting resistor.
Electrical note
Output is not rail-to-rail; check loading and dissipation.
PIN 4 · Control & reset
InputRESET
Function
Active-low reset overrides the timing cycle.
How to connect
Tie to VCC when reset is unused.
PIN 5 · Control & reset
ControlCONT
Function
Adjusts comparator reference levels.
How to connect
A small bypass capacitor to ground reduces noise when control is unused.
PIN 6 · Timing inputs
InputTHRES
Function
Ends the high interval above roughly 2VCC/3.
How to connect
Connect to the timing capacitor node.
PIN 7 · Outputs
Open collectorDISCH
Function
Discharges the timing capacitor during the low interval.
How to connect
Connect to the junction of the astable timing resistors.
PIN 8 · Supply
PowerVCC
Function
Positive supply.
How to connect
Use 4.5–16 V, with local supply decoupling.