NE555 Reference Tables, Pins & Specifications

Selected packagePDIP-8NE555P

Physical connections8 pinsPackage-specific numbering

Reference collection4 tables13 parameters & pin functions

Pin reference

Signal names, electrical functions and connection guidance

PDIP-8

Physical pin numbers8 pins

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NE555 pin functions and connections
Signal	Type	Function & connection
GND	Ground	Circuit reference. Connection guidance Connect to supply return.
TRIG	Input	Starts a timing cycle below roughly VCC/3. Connection guidance For astable operation, join TRIG to THRES at the capacitor node.
OUT	Output	Timer output. Connection guidance Drive the LED through a current-limiting resistor. Output is not rail-to-rail; check loading and dissipation.
RESET	Input	Active-low reset overrides the timing cycle. Connection guidance Tie to VCC when reset is unused.
CONT	Control	Adjusts comparator reference levels. Connection guidance A small bypass capacitor to ground reduces noise when control is unused.
THRES	Input	Ends the high interval above roughly 2VCC/3. Connection guidance Connect to the timing capacitor node.
DISCH	Open collector	Discharges the timing capacitor during the low interval. Connection guidance Connect to the junction of the astable timing resistors.
VCC	Power	Positive supply. Connection guidance Use 4.5–16 V, with local supply decoupling.

Reviewed manufacturer specifications

Manufacturer-referenced values4 parameters

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Parameter	Value	Conditions / notes
Supply	4.5–16 V	Recommended for NE555
Ambient	0–70°C	NE555 grade
Output	Up to ±200 mA	Do not ignore output drop or package dissipation
Supply absolute maximum	18 V	Stress limit, not an operating target

Reviewed manufacturer specifications

Manufacturer-referenced values5 parameters

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Parameter	Value	Conditions / notes
High interval	tH ≈ 0.693 (RA + RB) C	Standard astable circuit
Low interval	tL ≈ 0.693 RB C	Standard astable circuit
Frequency	f ≈ 1.44 / ((RA + 2RB) C)	R in ohms; C in farads
Duty cycle	D ≈ (RA + RB) / (RA + 2RB)	Greater than 50% in this basic circuit
Single pulse	t ≈ 1.1 RC	Monostable circuit

Reviewed manufacturer specifications

Manufacturer-referenced values4 parameters

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Parameter	Value	Conditions / notes
RA / RB / C	10 kΩ / 68 kΩ / 10 µF	Illustrative values
High time	≈0.541 s	Calculated ideal interval
Low time	≈0.471 s	Calculated ideal interval
Frequency	≈0.99 Hz	Approximate; tolerance changes the result