Datasheet

1161
SAM9G45 [DATASHEET]
Atmel-6438O-ATARM-SAM9G45-Datasheet_08-Dec-15
45.5 Main Oscillator Characteristics
Note: 1. The C
CRYSTAL
value is specified by the crystal manufacturer. In our case, C
CRYSTAL
must be between 15 pf and 20 pF. All
parasitic capacitance, package and board, must be calculated in order to reach 15 pF (minimum targeted load for the
oscillator) by taking into account the internal load C
INT
. So, to target the minimum oscillator load of 15 pF, external
capacitance must be: 15 pF - 4 pF = 11 pF which means that 22 pF is the target value (22 pF from XIN to GNDOSC and
22 pF from XOUT to GNDOSC). If 20 pF load is targeted, the sum of pad, package, board and external capacitances must
be 20 pF - 4 pF = 16 pF which means 32 pF (32 pF from XIN to GNDOSC and 32 pF from XOUT to GNDOSC).
Figure 45-2. Main Oscillator Schematic
45.5.1 Crystal Oscillator Characteristics
The following characteristics are applicable to the operating temperature range: T
A
= -40°C to 85°C and worst case of
power supply, unless otherwise specified.
Table 45-7. Main Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CPMAIN
) Crystal Oscillator Frequency – 8 12 16 MHz
C
CRYSTAL
(1)
Crystal Load Capacitance – 15 – 20 pF
C
INT
(1)
Internal Load Capacitance – – 4 – pF
C
LEXT
External Load Capacitance
C
CRYSTAL
= 15 pF
(1)
–22–pF
C
CRYSTAL
= 20 pF
(1)
–32–Pf
Duty Cycle – 40 50 60 %
t
START
Startup Time – – – 2 ms
I
DDSTDBY
Standby Current Consumption Standby mode – – 1 µA
P
ON
Drive Level – – – 150 µW
I
DD ON
Current Dissipation
@ 8 MHz 0.35 – 0.55 mA
@ 16 MHz 0.7 – 1.1 mA
XIN XOUT
GNDOSC
C
LEXT
C
LEXT
C
CRYSTAL
SAM9G45
Table 45-8. Crystal Characteristics
Symbol Parameter Conditions Min Typ Max Unit
ESR Equivalent Series Resistor Rs – – – 80 Ω
C
m
Motional Capacitance – – – 9 fF
C
SHUNT
Shunt Capacitance – – – 7 pF