CD00001237 datasheet(75/105 Pages) STMICROELECTRONICS

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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 RNET value, the

accuracy of the frequency is about 20%, so it may not be suitable for some applications.

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. RNET must have a positive temperature coefficient (ppm/°C), carbon resistors should therefore not be used.

Figure 51. Typical Application with RC Oscillator

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fOSC

RC oscillator frequency 1)

RNET=22 kΩ

RNET=47 kΩ

RNET=100 kΩ

RNET=220 kΩ

RNET=470 kΩ

7.2

5.1

3.2

1.8

0.9

8.6

5.7

3.4

1.9

0.95

6.5

3.8

1.1

MHz

RNET=22 kΩ

RNET=47 kΩ

RNET=100 kΩ

RNET=220 kΩ

RNET=470 kΩ

3.7

2.8

1.8

0.5

4.3

1.9

1.1

0.55

4.9

3.3

1.2

0.6

RNET

RC Oscillator external resistor 2)

see Figure 52 & Figure 53

870

OSCIN

OSCOUT

RNET

EXTERNAL RC

CEX~9pF DISCHARGE

ST62XX

VDD

fOSC

VDD

MIRROR

CURRENT

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