Atmel Xplained Pro Evaluation Kit ATSAMD20-XPRO ATSAMD20-XPRO Scheda Tecnica

586

Atmel | SMART SAM D20 [DATASHEET]

Atmel-42129K–SAM-D20_datasheet–06/2014

The following table describes the characteristics for the oscillator when a digital clock is applied on XIN.

The following table describes the characteristics for the oscillator when a crystal is connected between XIN and XOUT as 
shown in 

C

L 

is within the range 

given in the table. The exact value of C

L

 can be found in the crystal datasheet. The capacitance of the external capacitors 

(C

LEXT

) can then be computed as follows:

where C

STRAY

 is the capacitance of the pins and PCB, 

C

SHUNT

 is the shunt capacitance of the crystal.

f

CPXIN

XIN clock frequency

I

-

-

32

MHz

f

OUT

Crystal oscillator frequency

I

0.4

-

32

MHz

ESR

Crystal Equivalent Series 
Resistance
Safety Factor = 3

The AGC doesn’t have any 
noticeable impact on these 
measurements.

f = 0.455MHz, C

L

 = 100pF

XOSC.GAIN = 0

-

-

5.6K

Ω

f = 2MHz, C

L

 = 20pF

XOSC.GAIN = 0

-

-

416

f = 4MHz, C

L

 = 20pF

XOSC.GAIN = 1

-

-

243

f = 8MHz, C

L

 = 20pF

XOSC.GAIN = 2

-

-

138

f = 16MHz, C

L

 = 20pF

XOSC.GAIN = 3

-

-

66

f = 32MHz, C

L

 = 18pF

XOSC.GAIN = 4

-

-

56

C

XIN

Parasitic capacitor load

I

-

5.9

-

pF

C

XOUT

Parasitic capacitor load

-

3.2

-

pF

C

LEXT

2 C

L

C

STRAY

C

SHUNT

–

–

(

)

=