st72324bk STMicroelectronics, st72324bk Datasheet - Page 124

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

Electrical characteristics
11.5.1
124/167
Figure 64. Typical application with an external clock source
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 resonator 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 stabilization time. Refer to the crystal/ceramic resonator
manufacturer for more details (frequency, package, accuracy...).
Table 70.
1. The oscillator selection can be optimized in terms of supply current using an high quality resonator with
2. Data based on characterization results, not tested in production. The relatively low value of the RF resistor,
3. For C
f
R
C
C
i
V
V
2
OSC
Symbol
F
L1
L2
OSC1H
OSC1L
small RS value. Refer to crystal/ceramic resonator manufacturer for more details.
offers a good protection against issues resulting from use in a humid environment, due to the induced
leakage and the bias condition change. However, it is recommended to take this point into account if the
µC is used in tough humidity conditions.
designed for high-frequency applications and selected to match the requirements of the crystal or
resonator. C
capacitance which is the series combination of C
included when sizing C
capacitance).
External
clock source
L1
and C
Oscillator frequency
Feedback resistor
Recommended load capacitance
versus equivalent serial resistance of
the crystal or ceramic resonator (R
OSC2 driving current
Crystal and ceramic resonator oscillators
L1
L2
and C
it is recommended to use high-quality ceramic capacitors in the 5-pF to 25-pF range (typ.)
t
r(OSC1)
L2
, are usually the same size. The crystal manufacturer typically specifies a load
L1
and C
Parameter
(2)
L2
(1)
t
f(OSC1)
(10 pF can be used as a rough estimate of the combined pin and board
OSC2
OSC1
90%
10%
S
L1
)
(3)
and C
f
f
f
f
V
f
f
f
f
t
Not connected internally
OSC
OSC
OSC
OSC
OSC
OSC
OSC
OSC
w(OSC1H)
L2
IN
. PCB and MCU pin capacitance must be
Conditions
= V
= 1 to 2 MHz
= 2 to 4 MHz
= 4 to 8 MHz
= 8 to 16 MHz
= 2 to 4 MHz
= 4 to 8 MHz
= 1 to 2 MHz
= 8 to 16 MHz
SS
I
L
t
w(OSC1L)
f
OSC
Min
160
310
610
20
20
20
15
15
80
1
ST72XXX
ST72323 ST72323L
Max
150
250
460
910
16
40
60
50
35
35
MHz
Unit
kΩ
µA
pF