st72f321r STMicroelectronics, st72f321r Datasheet - Page 148

• Manufacturer Part Number: st72f321r
• Description: 64/44-pin 8-bit Mcu With 32 To 60k Flash/rom, Adc, Five Timers, Spi, Sci, I2c Interface
• Manufacturer: STMicroelectronics

ST72321
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 are based
on characterization results with specified typical
external components. In the application, the reso-
nator and the load capacitors have to be placed as
Figure 78. Typical Application with a Crystal or Ceramic Resonator
Notes:
1. The oscillator selection can be optimized in terms of supply current using an high quality resonator with small R
Refer to crystal/ceramic resonator manufacturer for more details.
2. Data based on characterisation results, not tested in production.
148/189
f
R
C
C
i
2
OSC
Symbol
Symbol
F
L1
L2
WHEN RESONATOR WITH
INTEGRATED CAPACITORS
Oscillator Frequency
Feedback resistor
Recommended load capacitance ver-
sus equivalent serial resistance of the
crystal or ceramic resonator (R
OSC2 driving current
C
L2
Parameter
Parameter
C
L1
2)
1)
RESONATOR
S
)
LP: Low power oscillator
MP: Medium power oscillator
MS: Medium speed oscillator
HS: High speed oscillator
R
R
R
R
V
V
OSC1
OSC2
DD
IN
S
S
S
S
=200
=200
=200
=100
=V
=5V
SS
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...).
Conditions
Conditions
R
F
LP oscillator
MP oscillator
MS oscillator
HS oscillator
LP oscillator
MP oscillator
MS oscillator
HS oscillator
i
2
Min
Typ
160
310
610
>2
>4
>8
20
22
22
18
15
80
1
ST72XXX
f
OSC
Max
Max
150
250
460
910
16
40
56
46
33
33
2
4
8
S
MHz
Unit
Unit
k
pF
value.
A