SA555 Fairchild Semiconductor, SA555 Datasheet - Page 10
SA555
Manufacturer Part Number
SA555
Description
Timers & Support Products
Manufacturer
Fairchild Semiconductor
Type
Standardr
Datasheet
1.SA555.pdf
(14 pages)
Specifications of SA555
Number Of Internal Timers
1
Supply Voltage (max)
16 V
Supply Voltage (min)
4.5 V
Maximum Power Dissipation
600 mW
Maximum Operating Temperature
+ 85 C
Minimum Operating Temperature
- 40 C
Mounting Style
Through Hole
Package / Case
PDIP-8
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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Company
Part Number
Manufacturer
Quantity
Price
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S
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20 000
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Part Number:
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Manufacturer:
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Quantity:
20 000
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Manufacturer:
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S
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LM555/NE555/SA555
When the trigger starts in a timer configured as shown in Figure 13, the current flowing through capacitor C1 becomes a
constant current generated by PNP transistor and resistors.
Hence, the V
follows:
Here the Vp-p is the peak-to-peak voltage.
If the electric charge amount accumulated in the capacitor is divided by the capacitance, the V
V=Q/C
The above equation divided on both sides by T gives us
and may be simplified into the following equation.
S=I/C
In other words, the gradient of the linear ramp function appearing across the capacitor can be obtained by using the constant
current flowing through the capacitor.
If the constant current flow through the capacitor is 0.215mA and the capacitance is 0.02 F, the gradient of the ramp function
at both ends of the capacitor is S = 0.215m/0.022 = 9.77V/ms.
10
10
10
10
S
V
--- -
T
=
=
V p p
----------------
Q T
----------- -
T
–
C
C
is a linear ramp function as shown in Figure 14. The gradient S of the linear ramp function is defined as
14
(15)
(17)
16
C
comes out as follows: