Atmel SAM9X25, Manual

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11054A–ATARM–27-Jul-11
SAM9X25
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11054A–ATARM–27-Jul-11
SAM9X25
46.4 Clock Characteristics
46.4.1 Processor Clock Characteristics
46.4.2 Master Clock Characteristics
The master clock is the maximum clock at which the system is able to run. It is given by the
smallest value of the internal bus clock and EBI clock.
Note: 1. For DDR2 usage only, there are no limitations to LP-DDR, SDRAM and mobile SDRAM.
46.5 Main Oscillator Characteristics
Note: 1. The C
CRYSTAL
value is specified by the crystal manufacturer. In our case, C
CRYSTAL
must be between 17.5 pF and 20 pF. All
parasitic capacitance, package and board, must be calculated in order to reach 17.5 pF (minimum targeted load for the
oscillator) by taking into account the internal load C
INT
. So, to target the minimum oscillator load of 17.5 pF, external capaci-
tance must be: 17.5 pF - 4 pF = 13.5 pF which means that 27 pF is the target value (27 pF from xin to gnd and 27 pF from
xout to gnd). 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 gnd and 32 pF from xout to gnd).
Table 46-5. Processor Clock Waveform Parameters
Symbol Parameter Conditions Min Max Units
1/(t
CPPCK
) Processor Clock Frequency
VDDCORE = 0.9V
T = 85°C
125
(1)
400 MHz
Table 46-6. Master Clock Waveform Parameters
Symbol Parameter Conditions Min Max Units
1/(t
CPMCK
) Master Clock Frequency
VDDCORE = 0.9V
T = 85°C
125
(1)
133 MHz
Table 46-7. Main Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(t
CPMAIN
) Crystal Oscillator Frequency 12 16 MHz
C
CRYSTAL
(1)
Crystal Load Capacitance 17.5 20 pF
C
LEXT
External Load Capacitance
C
CRYSTAL
= 17.5 pF
(1)
27 pF
C
CRYSTAL
= 20 pF
(1)
32 pF
Duty Cycle 40 60 %
t
ST
Startup Time 2 ms
I
DDST
Standby Current Consumption Standby mode 1 μA
P
ON
Drive Level 150 μW
I
DD ON
Current Dissipation
@ 12 MHz 0.52 0.55 mA
@ 16 MHz 0.7 1.1 mA