Datasheet

ST72321Rx ST72321ARx ST72321Jx
147/193
CLOCK AND TIMING CHARACTERISTICS (Cont’d)
12.5.3 Crystal and Ceramic Resonator Oscillators
The ST7 internal clock can be supplied with four
different Crystal/Ceramic resonator oscillators. All
the information given in this paragraph is based on
characterization results with specified typical ex-
ternal components. In the application, the resona-
tor and the load capacitors have to be placed as
close as possible to the oscillator pins in order to
minimize output distortion and start-up stabiliza-
tion time. Refer to the crystal/ceramic resonator
manufacturer for more details (frequency, pack-
age, accuracy...).
Notes:
1. The oscillator selection can be optimized in terms of supply current using an high quality resonator with small R
S
value.
Refer to crystal/ceramic resonator manufacturer for more details.
2. Data based on characterisation results, not tested in production.
Symbol Parameter Conditions Min Max Unit
f
OSC
Oscillator Frequency
1)
LP: Low power oscillator
MP: Medium power oscillator
MS: Medium speed oscillator
HS: High speed oscillator
1
>2
>4
>8
2
4
8
16
MHz
R
F
Feedback resistor
2)
20 40 kΩ
C
L1
C
L2
Recommended load capacitance ver-
sus equivalent serial resistance of the
crystal or ceramic resonator (R
S
)
R
S
=200Ω LP oscillator
R
S
=200Ω MP oscillator
R
S
=200Ω MS oscillator
R
S
=100Ω HS oscillator
22
22
18
15
56
46
33
33
pF
Symbol Parameter Conditions Typ Max Unit
i
2
OSC2 driving current
V
DD
=5V LP oscillator
V
IN
=V
SS
MP oscillator
MS oscillator
HS oscillator
80
160
310
610
150
250
460
910
μA