Datasheet

1431
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
47.4.3 32.768 kHz Crystal Oscillator Characteristics
Note: 1. R
S
is the series resistor.
Figure 47-11. 32.768 kHz Crystal Oscillator Schematics
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 SAM4 pin.
Table 47-18. 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 < 50 kΩ
Rs < 100 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
C
crystal
= 12.5 pF
C
crystal
= 6 pF
—
—
—
—
—
—
—
—
900
300
1200
500
ms
I
DDON
Current consumption
Rs < 50 kΩ
Rs < 100 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
C
crystal
= 12.5 pF
C
crystal
= 6 pF
—
—
—
—
550
380
820
530
1150
980
1600
1350
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
———20pF
C
PARA
Internal Parasitic Capacitance — 0.6 0.7 0.8 pF
XIN32
XOUT32
C
LEXT
C
LEXT
SAM4