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Precision Timer. NE555 Datasheet |
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NE555
PRECISION TIMER
Description
These devices are precision timing circuits capable of producing
accurate time delays or oscillation. In the time-delay or monostable
mode of operation, the timed interval is controlled by a single external
resistor and capacitor network. In the astable 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.
Pin Assignments
GND
TRIG
OUT
RESET
(Top View)
SO-8
The output circuit is capable of sinking or sourcing current up to
200mA. Operation is specified for supplies of 5V to 15V. With a 5-V
supply, output levels are compatible with TTL inputs.
VCC
DISCH
THRES
CONT
Features
• Timing from microseconds to hours
• Astable or monostable operation
• Adjustable duty cycle
• TTL compatible output can source or sink up to 200mA
• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
• Halogen- and Antimony-Free. “Green” Device (Note 3)
• For automotive applications requiring specific change
control (i.e. parts qualified to AEC-Q100/101/200, PPAP
capable, and manufactured in IATF 16949 certified
facilities), please contact us or your local Diodes
representative.
https://www.diodes.com/quality/product-definitions/
Notes:
1. No purposely added lead. FullyEU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3).compliant.
2. See https://www.diodes.com/quality/lead-free/ formore information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl)
and <1000ppm antimony compounds.
NE555/SA555/NA555
Document number: DS35112 Rev. 5 - 2
1 of 14
www.diodes.com
February 2021
© Diodes Incorporated
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Pin Descriptions
Pin Name
GND
TRIG
OUT
RESET
CONT
THRES
DISCH
VCC
Pin Number
1
2
3
4
5
6
7
8
Description
Ground
Trigger set 1/3VCC
Timer output
Reset active low
External adjustment of internal threshold and trigger voltages
Threshold set to 2/3 VCC
Low impedance discharge path
Chip supply voltage
NE555
Functional Block Diagram
VCC CONT
8
5
THRES 6
RESET
4
R1
R2
O
S
3 OUT
2
TRIG
1
GND
7 DISCH
RESET can override TRIG, which can override THRESH
Functional Table
RESET
Low
High
High
High
Nominal Trigger
Voltage
Irrelevant
<1/3VCC
>1/3VCC
>1/3VCC
Threshold
Voltage
Irrelevant
Irrelevant
>2/3VCC
<2/3VCC
Output
Discharge
Switch
Low
On
High
Off
Low
On
As previously established
NE555/SA555/NA555
Document number: DS35112 Rev. 5 - 2
2 of 14
www.diodes.com
February 2021
© Diodes Incorporated
|
NE555
Absolute Maximum Ratings (Note 4) @ TA = 25°C unless otherwise stated
Symbol
Parameter
Rating
Unit
VCC
VI
IO
θJA
θJC
TJ
TSTG
Supply voltage (Note 5)
Input voltage
CONT, RESET, THRES, TRIG
Output current
Package thermal resistance Junction-to-Ambient (Note 6)
Package thermal resistance Junction-to-Case (Note 7)
Junction temperature
Storage temperature
18
VCC
±225
130
15
150
-65 to 150
V
V
mA
°C/W
°C/W
°C
°C
Notes:
4. Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratings only.
Functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
5. All voltage values are with respect ground.
6. Maximum power dissipation is a function of TJ(max), θJA, and TA. The maximum allowable power dissipation at any allowable ambient temperature is
PD = (TJ(max) – TA)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability.
7. Maximum power dissipation is a function of TJ(max), θJC, and TA. The maximum allowable power dissipation at any allowable ambient temperature is
PD = (TJ(max) – TC)/θJA. Operating at the absolute maximum TJ of 150°C can affect reliability.
Recommended Operating Conditions (TA = 25°C)
Symbol
VCC
VI
IO
TA
Parameter
Supply voltage
Input voltage
CONT, RESET, THRES, TRIG
Output current
NE555
Operating Ambient Temperature
SA555
NA555
Min
Max
Unit
4.5
16
V
—
VCC
V
—
±200
mA
0
70
-40
85
°C
-40
105
Electrical Characteristics (VCC = 5V to 15V, TA = 25°C unless otherwise stated)
Symbol
Parameter
Test conditions
Min Typ. Max Unit
VTH
Threshold voltage level
ITH
Threshold current (Note 8)
VCC = 15V
VCC = 5V
—
8.8
10
11.2
V
2.4
3.3
4.2
—
30
250
nA
VTR
Trigger voltage level
VCC = 15V
VCC = 5V
4.5
5
5.6
V
1.1
1.67
2.2
ITR
Trigger current
TRIG at 0V
—
0.5
2
µA
VRST
RESET voltage level
—
0.3
0.7
1
V
IRST
RESET current
RESET at VCC
RESET at 0V
—
0.1
0.4
mA
—
-0.4
-1.5
IDIS
DISCH switch off-state current
—
—
20
100
nA
VDIS
DISCH saturation voltage with output VCC = 15V, IDIS = 15mA
low (Note 9)
VCC = 5V, IDIS = 4.5mA
—
180
480
mV
—
80
200
VCON
CONT voltage (open circuit)
VCC = 15V
VCC = 5V
9
10
11
V
2.6
3.3
4
Notes:
8. This parameter influences the maximum value of the timing resistors RA and RB in the circuit of Figure 12. For example, when VCC = 5 V, the
maximum value is R = RA + RB ≉ 3.4MΩ, and for VCC = 15 V, the maximum value is 10MΩ.
9. No protection against excessive pin 7 current is necessary providing package dissipation rating is not exceeded
NE555/SA555/NA555
Document number: DS35112 Rev. 5 - 2
3 of 14
www.diodes.com
February 2021
© Diodes Incorporated
|
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