Datasheet

712
11011B–ATARM–21-Feb-12
SAM3N
35.4.3 32.768 kHz Crystal Oscillator Characteristics
Note: 1. R
S
is the series resistor.
C
LEXT
= 2x(C
CRYSTAL
– C
para
– C
PCB
)
Where
C
PCB
is the capacitance of the printed circuit board (PCB) track layout from the crystal to the SAM3 pin.
35.4.4 32.768 kHz Crystal Characteristics
Table 35-21. 32.768 kHz Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
F
req
Operating Frequency Normal mode with crystal 32.768 KHz
Supply Ripple Voltage (on VDDIO) Rms value, 10 KHz to 10 MHz 30 mV
Duty Cycle 40 50 60 %
Startup Time
Rs < 50KΩ
Rs < 100KΩ
(1)
C
crystal
= 12.5pF
C
crystal
= 6pF
C
crystal
= 12.5pF
C
crystal
= 6pF
900
300
1200
500
ms
Current consumption
Rs < 50KΩ
Rs < 100KΩ
(1)
C
crystal
= 12.5pF
C
crystal
= 6pF
C
crystal
= 12.5pF
C
crystal
= 6pF
650
450
900
650
1400
1200
1600
1400
nA
P
ON
Drive level 0.1 µW
R
f
Internal resistor between XIN32 and XOUT32 10 MΩ
C
LEXT
Maximum external capacitor
on XIN32 and XOUT32
20 pF
C
para
Internal Parasitic Capacitance 0.8 1 1.2 pF
XIN32
XOUT32
C
LEXT
C
LEXT
SAM3
Table 35-22. Crystal Characteristics
Symbol Parameter Conditions Min Typ Max Unit
ESR Equivalent Series Resistor (R
S)
Crystal @ 32.768 KHz 50 100 KΩ
C
M
Motional capacitance Crystal @ 32.768 KHz 0.6 3 fF
C
SHUNT
Shunt capacitance Crystal @ 32.768 KHz 0.6 2 pF