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NE555 Timer IC: Pinout, Circuit, Application [FAQ]

Author: Iggy Date: 7 Apr 2021  78

The NE555 timer IC is an integrated circuit (chip) used in a variety of timer, delay, pulse generation, and oscillator applications.

This blog provides you with a basic overview of the NE555 Timer IC, including its pin descriptions, functions and specifications, alternative products, etc., to help you quickly understand what NE555 is. We will be glad to find that this blog can be useful for people loving electronic components 😊

How a 555 Timer IC Works?

Catalog

NE555 Pinout

NE555 Features

NE555 Advantage

NE555 Circuit

NE555 Parameters

NE555 Package

NE555 CAD/CAE symbols

NE555 Manufacturer

Component Datasheet

FAQ


NE555 Pinout

NE555 Pinout

The pinout of the 8-pin NE555 timer and 14-pin 556 dual timer are shown in the following table. Since the 556 is conceptually two 555 timers that share power pins, the pin numbers for each half is split across two columns.

In the following table, longer pin names are used, because manufacturers never standardized the abbreviated pin names across all datasheets.

Pin No.

Pin Name

Pin Direction

Pin Description

1

GND

Power

Ground supply: this pin is the ground reference voltage (zero volts).

2

TRIGGER

Input

Trigger: when the voltage at this pin falls below ​1⁄2 of the voltage of CONTROL (​1⁄3 VCC, except when CONTROL is driven by an external signal), the OUTPUT goes to the high state and a timing interval starts. As long as this pin continues to be kept at a low voltage, the OUTPUT will remain in the high state.

3

OUTPUT

Output

Output: this pin is a push-pull (P.P.) output that is driven to either a low state (GND) or a high state (for bipolar timers, VCC minus approximately 1.7 volts) (for CMOS timers, VCC). For bipolar timers, this pin can drive up to 200 mA, but CMOS timers are able to drive less (varies by chip). For bipolar timers, if this pin drives an edge-sensitive input of a digital logic chip, a 100 to 1000 pF decoupling capacitor (between this pin and GND) may need to be added to prevent double triggering.

4

RESET

Input

Reset: a timing interval may be reset by driving this pin to GND, but the timing does not begin again until this pin rises above approximately 0.7 volts. This pin overrides TRIGGER, which in turn overrides THRESHOLD. If this pin is not used, it should be connected to VCC to prevent electrical noise accidentally causing a reset.

5

CONTROL

Input

Control: this pin provides access to the internal voltage divider (​2⁄3 VCC by default). By applying a voltage to this pin, the timing characteristics can be changed. In astable mode, this pin can be used to frequency-modulate the OUTPUT state. If this pin is not used, it should be connected to a 10 nF decoupling capacitor (between this pin and GND) to ensure electrical noise doesn't affect the internal voltage divider.

6

THRESHOLD

Input

Threshold: when the voltage at this pin is greater than the voltage at CONTROL (​2⁄3 VCC except when CONTROL is driven by an external signal), then the OUTPUT high state timing interval ends, causing the OUTPUT to go to the low state.

7

DISCHARGE

Output

Discharge: For bipolar timers, this pin is an open-collector (O.C.) output, CMOS timers are open-drain (O.D.). This pin can be used to discharge a capacitor between intervals, in phase with the OUTPUT. In bistable mode and schmitt trigger mode, this pin is unused, which allows it to be used as an alternate output.

8

VCC

Power

Positive supply: For bipolar timers, the voltage range is typically 4.5 to 16 volts, some are spec'ed for up to 18 volts, though most will operate as low as 3 volts. For CMOS timers, the voltage range is typically 2 to 15 volts, some are spec'ed for up to 18 volts, and some are spec'ed as low as 1 volt. See the supply min and max columns in the derivatives table in this article. Decoupling capacitor(s) are generally applied (between this pin and GND) as a good practice.


NE555 Features

  • Timing From Microseconds to Hours
  • Astable or Monostable Operation
  • Adjustable Duty Cycle
  • TTL-Compatible Output Can Sink or Source Up to 200 mA
  • On Products Compliant to MIL-PRF-38535, All Parameters Are Tested Unless Otherwise Noted. On All Other Products, Production Processing Does Not Necessarily Include Testing of All Parameters.

NE555 Advantage

NE555 Timer IC

NE555 Timer IC

These devices are precision timing circuits capable of producing accurate time delays or oscillation. In the time-delay or mono-stable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the a-stable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor.

The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. These levels can be altered by use of the control-voltage terminal. When the trigger input falls below the trigger level, the flip-flop is set, and the output goes high. If the trigger input is above the trigger level and the threshold input is above the threshold level, the flip-flop is reset and the output is low. The reset (RESET) input can override all other inputs and can be used to initiate a new timing cycle. When RESET goes low, the flip-flop is reset, and the output goes low. When the output is low, a low-impedance path is provided between discharge (DISCH) and ground.

The output circuit is capable of sinking or sourcing current up to 200 mA. Operation is specified for supplies of 5 V to 15 V. With a 5-V supply, output levels are compatible with TTL inputs.


NE555 Circuit

  • Missing-Pulse Detector

NE555 Application: Missing-Pulse Detector

  • Pulse-Width Modulation

NE555 Application: Pulse-Width Modulation

  • Pulse-Position Modulation

NE555 Application: Pulse-Position Modulation

  • Sequential Timer

NE555 Application: Sequential Timer


NE555 Parameters

VCC (Min) (V)

4.5

VCC (Max) (V)

16

Iq (Typ) (uA)

2000

Rating

Catalog

Operating temperature range (C)

0 to 70


NE555 Package

Package

Pins

Size

PDIP (P)

8

93 mm² 9.81 x 9.43

SOIC (D)

8

19 mm² 3.91 x 4.9

SOIC (D)

8

19 mm² 4.9 x 3.9

SOP (PS)

8

48 mm² 6.2 x 7.8

TSSOP (PW)

8

19 mm² 3 x 6.4


NE555 CAD/CAE symbols

Package

Pins

Download

PDIP (P)

8

View options

SO (PS)

8

View options

SOIC (D)

8

View options

TSSOP (PW)

8

View options


NE555 Manufacturer

TI Logo

Texas Instruments Inc. (TI)  is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.


Component Datasheet

NE555 Datasheet


FAQ

  • What does a 555 timer do?

The 555 timer IC is a very cheap, popular and useful precision timing device which can act as either a simple timer to generate single pulses or long time delays, or as a relaxation oscillator producing a string of stabilised waveforms of varying duty cycles from 50 to 100%.

  • How do I know if my IC is ne555?

How to Check the 555 Timer IC? First of all, insert the IC in socket (if used) very carefully so that no pin of 555 timer gets damage. Now to see the result, switch on the power supply. If your 555 timer is working properly, then both the LEDs (Red LEDs in my case) will glow alternately.

  • Are all 555 timers the same?

Overall, most bipolar 555 chips are either identical or very closely related to each other, though some have minor design differences. There is more variations between the CMOS 555 chips, because of the push towards redesigns that work at lower operating voltage and lower standby current.

  • How do you trigger a 555?

Usually the timer IC 555 is triggered by applying a negative going pulse to its trigger pin 2. This timer is triggered through a positive pulse in its reset pin. In the monostable mode IC 555 starts timing cycle when a negative pulse is applied to its trigger pin 2.

  • How do you use a 555 chip?

Use jumper wire to connect pins 4 and 8 to each other (red) and pins 2 and 6 to each other (yellow). Attach the positive lead of a speaker to pin 3 of the 555 and connect the negative lead to ground (pin 1). Low values of RA should be avoided because they prevent the 555 timer from discharging the capacitor C normally.

  • How do you use a 555 timer?

With a 555 timer, we can produce clock signals of varying frequencies based on the values of the external resistors and capacitor that we choose. We can produce clock signals of any frequency needed. A 1Hz clock signal will cycle once every second. A 2Hz clock signal will cycle every 0.5 seconds.

 

Ordering & Quality

Photo Mfr. Part # Company Description Package PDF Qty Pricing
(USD)
NE555DG4 NE555DG4 Company:Texas Instruments Remark:IC OSC SGL TIMER 100KHZ 8-SOIC Package:8-SOIC (0.154", 3.90mm Width)
DataSheet
In Stock:1489
Inquiry
Price:
1+: $0.41000
10+: $0.32900
25+: $0.30120
100+: $0.22400
250+: $0.20300
500+: $0.16800
1000+: $0.12600
2500+: $0.11550
5000+: $0.10850
Inquiry
NE555DR NE555DR Company:Texas Instruments Remark:IC OSC SGL TIMER 100KHZ 8-SOIC Package:8-SOIC (0.154", 3.90mm Width)
DataSheet
In Stock:45000
Inquiry
Price:
2500+: $0.08100
5000+: $0.07650
12500+: $0.06975
25000+: $0.06525
62500+: $0.05850
Inquiry
NE555N NE555N Company:STMicroelectronics Remark:IC OSC SINGLE TIMER 500KHZ 8-DIP Package:8-DIP (0.300", 7.62mm)
DataSheet
In Stock:On Order
Inquiry
Price:
8000+: $0.10075
Inquiry
NE555P NE555P Company:Texas Instruments Remark:IC OSC SINGLE TIMER 100KHZ 8-DIP Package:8-DIP (0.300", 7.62mm)
DataSheet
In Stock:51134
Inquiry
Price:
1+: $0.45000
10+: $0.34200
25+: $0.30800
100+: $0.21280
250+: $0.17920
500+: $0.14560
1000+: $0.11200
2500+: $0.10080
5000+: $0.09520
Inquiry
NE555PWR NE555PWR Company:Texas Instruments Remark:555 Type, Timer/Oscillator (Single) IC 100kHz 8-TSSOP Package:8-TSSOP (0.173"", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.41000
10+: $0.30500
25+: $0.27520
100+: $0.19000
250+: $0.16000
500+: $0.13000
1000+: $0.10000
2000+: $0.09000
6000+: $0.08500
10000+: $0.07750
50000+: $0.06500
Inquiry

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