sa555d-dt STMicroelectronics, sa555d-dt Datasheet - Page 14

• Manufacturer Part Number: sa555d-dt
• Description: General Purpose Single Bipolar Timers
• Manufacturer: STMicroelectronics

Application information
4.5
14/20
Figure 20
The time interval is given by:
Figure 20. Linear ramp
50% duty cycle oscillator
For a 50% duty cycle, the resistors R
period for the output high is the same as for astable operation (see
For the output low it is
Thus the frequency of oscillation is:
t1 = 0.693 R
shows the waveforms generator by the linear ramp.
A
C
V
Time:
20µs/DIV
R
R
R
C = 0.01µF
t
2
CC
1
2
E
T =
=
= 100kΩ
+ 47kΩ
= 2.7kΩ
= 5V
[(R. RB)/(RA+RB)].C.Ln
--------------------------------------------------------------- - VBE = 0.6V
(2/3 Vcc RE (R1+R2) C
R1 Vcc - VBE (R1+R2)
A
and R
Top trace: input 3V/DIV
Middle trace: output 5V/DIV
Bottom trace: output 5V/DIV
Bottom trace: capacitor voltage 1V/DIV
f
=
E
---------------- -
t1
can be connected as in figure 19. The time
1
+
t2
RB 2RA
-------------------------- -
2RB RA
–
–
NE555 - SA555 - SE555
Section 4.2 on page
10):