AN2353

Oscillator

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The minimal gain of the amplifier also implicitly sets the on-chip oscillator start-up time.

The oscillation stability mainly depends on external parameters so only the

measurement at the application level.

1.2

Start-up time

Ceramic resonators have a much shorter start-up time than crystals (about 100 times faster)

but have a lower accuracy on the frequency (initial tolerance, temperature variations and

drift).

Depending on applications requirements and possibilities, users can choose between short

oscillator start-up time and frequency accuracy.

From an ST10 perspective, the worst case condition / environment for the oscillator start-up

time is high temperature and low voltage.

Table 1.

Symbol

Parameter

Version

Conditions

Value

Unit

Min

Typ

Max

Oscillator transconductance

Wide-swing

8

17

35

mA/V

Low-power

0.7

2.5

6

32 kHz

Start-up

20

31

50

µ

A/V

Normal run

8

17

30

gm

min

Rs

C

2

×ω

2

×

Rs

C

2

×

2

π

×

f

×

()

2

×

==