Datasheet

ST72334J/N, ST72314J/N, ST72124J
117/153
CLOCK AND TIMING CHARACTERISTICS (Cont’d)
16.5.3 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
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...).
16.5.3.1 Typical Crystal Resonators
Figure 68. Application with a Crystal Resonator
Notes:
1. Resonator characteristics given by the crystal manufacturer.
2. t
SU(OSC)
is the typical oscillator start-up time measured between V
DD
=2.8V and the fetch of the first instruction (with a
quick V
DD
ramp-up from 0 to 5V (<50µs).
3. The oscillator selection can be optimized in terms of supply current using an high quality resonator with small R
S
value.
Refer to crystal manufacturer for more details.
Symbol Parameter Conditions Min Max Unit
f
OSC
Oscillator Frequency
3)
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 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
38
32
18
15
56
46
26
21
pF
i
2
OSC2 driving current
V
DD
=5V LP oscillator
V
IN
=V
SS
MP oscillator
MS oscillator
HS oscillator
40
110
180
400
100
190
360
700
µA
Option
Byte
Config.
Reference Freq. Characteristic
1)
C
L1
[pF]
C
L2
[pF]
t
SU(osc)
[ms]
2)
LP
JAUCH
S-200-30-30/50
2MHz
∆f
OSC
=[±30ppm
25°C
,±30ppm
∆Ta
], Typ. R
S
=200Ω 33 34 10~15
MP SS3-400-30-30/30
4MHz
∆f
OSC
=[±30ppm
25°C
,±30ppm
∆Ta
], Typ. R
S
=60Ω 33 34 7~10
MS SS3-800-30-30/30
8MHz
∆f
OSC
=[±30ppm
25°C
,±30ppm
∆Ta
], Typ. R
S
=25Ω 33 34 2.5~3
HS SS3-1600-30-30/30
16MHz
∆f
OSC
=[±30ppm
25°C
,±30ppm
∆Ta
], Typ. R
S
=15Ω 33 34 1~1.5
OSC2
OSC1
f
OSC
C
L1
C
L2
i
2
R
F
ST72XXX
RESONATOR