Datasheet

DRAFT
1395
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
45.4.3 32.768 kHz Crystal Oscillator Characteristics
Notes: 1. R
S
is the series resistor.
Figure 45-12. 32.768 kHz Crystal Oscillator Schematics
C
LEXT
= 2 × (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.
Table 45-17. 32.768 kHz Crystal Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
f
OSC
Operating Frequency Normal mode with crystal 32.768 kHz
V
rip(VDDBU)
Supply Ripple Voltage (on VDDBU) RMS value, 10 kHz to 10 MHz 30 mV
Duty Cycle 40 50 60 %
t
START
Startup Time
R
S
< 50 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
900
300
ms
R
S
< 100 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
1200
500
I
DDON
Current Consumption
R
S
< 50 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
650
450
1400
1200
nA
R
S
< 100 kΩ
(1)
C
crystal
= 12.5 pF
C
crystal
= 6 pF
900
650
1600
1400
I
DDST
Standby Current Consumption Standby mode @ 3.6V 5 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
crystal
Allowed Crystal Capacitance Load From crystal specification 6 12.5 pF
C
para
Internal Parasitic Capacitance 1.2 1.4 1.6 pF
XIN32
XOUT32
C
LEXT
C
crystal
C
LEXT
SAM3