Specifications

ST72325xx
150/197
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)
116MHz
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
)
3)
f
OSC
= 1 to 2 MHz
f
OSC
= 2 to 4 MHz
f
OSC
= 4 to 8 MHz
f
OSC
= 8 to 16 MHz
20
20
15
15
60
50
35
35
pF
Symbol Parameter Conditions Typ Max Unit
i
2
OSC2 driving current
V
DD
=5V:
f
OSC
= 2MHz, C0 = 6pF, Cl1 = Cl2 = 68pF
f
OSC
= 4MHz, C0 = 6pF, Cl1 = Cl2 = 68pF
f
OSC
= 8MHz, C0 = 6pF, Cl1 = Cl2 = 40pF
f
OSC
= 16MHz, C0 = 7pF, Cl1 = Cl2 = 20pF
426
425
456
660
µA