CD00001237 Datasheet, PDF (75/105 Pages) STMicroelectronics – 8-bit MCUs with A/D converter

ST6215C ST6225C
CLOCK AND TIMING CHARACTERISTICS (Cont’d)
11.5.4 RC Oscillator
The ST6 internal clock can be supplied with an external RC oscillator. Depending on the R_NET value, the
accuracy of the frequency is about 20%, so it may not be suitable for some applications.
Symbol
Parameter
Conditions
Min Typ Max Unit
f_OSC
RC oscillator frequency ¹⁾
R_NET
RC Oscillator external resistor ²⁾
R_NET=22 kΩ
7.2
R_NET=47 kΩ
5.1
R_NET=100 kΩ
3.2
R_NET=220 kΩ
1.8
R_NET=470 kΩ
0.9
R_NET=22 kΩ
3.7
R_NET=47 kΩ
2.8
R_NET=100 kΩ
1.8
R_NET=220 kΩ
1
R_NET=470 kΩ
0.5
see Figure 52 & Figure 53 22
8.6
5.7
3.4
1.9
0.95
4.3
3
1.9
1.1
0.55
10
6.5
3.8
2
1.1
MHz
4.9
3.3
2
1.2
0.6
870 kΩ
Notes:
1. Data based on characterization results, not tested in production. These measurements were done with the OSCin pin
unconnected (only soldered on the PCB).
2. R_NET must have a positive temperature coefficient (ppm/°C), carbon resistors should therefore not be used.
Figure 51. Typical Application with RC Oscillator
EXTERNAL RC
OSC_OUT
R_NET
OSC_IN
NC
f_OSC
V_DD
V_DD
V_DD
MIRROR
CURRENT
C_EX~9pF DISCHARGE
ST62XX
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