Datasheet

September 1993 20
Philips Semiconductors Product specification
Programmable delay timer with oscillator 74HC/HCT5555
APPLICATION INFORMATION
Fig.11 Test set-up for measuring forward
transconductance g
fs
= di
o
/dv
i
at v
o
is
constant (see Fig.12) and MR = LOW.
handbook, halfpage
MGA645
A
output
100 F
V
CC
input
0.47 F
R = 560 kΩ
bias
i
o
(f = 1 kHz)
GND
v
i
µ
µ
Fig.12 Typical forward transconductance g
fs
as a
function of the supply voltage at V
CC
at
T
amb
= 25 °C.
handbook, halfpage
MBA333
14
12
10
8
6
4
2
0123456
g
fs
(mA/V)
CC
V
(V)
max.
min.
typ.
Fig.13 Application information.
C
t
curve at R
t
= 100 kΩ; R2 = 200 kΩ.
R
t
curve at C
t
= 1 nF; R2 = 2 x R
t
.
RC oscillator frequency as a function of R
t
and C
t
at V
CC
= 2 to 6 V; T
amb
= 25 °C.
handbook, halfpage
10
3
MGA647
10
4
10
5
10
6
10
10
5
10
3
10
4
10
2
f
osc
(Hz)
R ( )
t
C ( F)
t
10
–4
10
–3
10
–2
10
–1
R
t
C
t
Ω
µ
Fig.14 Example of an RC oscillator.
Typical formula for oscillator frequency:
f
osc
1
2.5 R
t
C
t
××
--------------------------------
=
handbook, halfpage
MGA646
2
RS1
MR (from logic)
R
TC
C
TC
3
R
t
C
t
C2 R2