SAM4L Datasheet, PDF (1125/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

ATSAM4L4/L2
42.6 Oscillator Characteristics
42.6.1 Oscillator 0 (OSC0) Characteristics
42.6.1.1
Digital Clock Characteristics
The following table describes the characteristics for the oscillator when a digital clock is applied
on XIN.
Table 42-19. Digital Clock Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Units
f_CPXIN
t_CPXIN
XIN clock frequency ⁽¹⁾
XIN clock duty cycle⁽¹⁾
50
MHz
40
60
%
t_STARTUP
Startup time
N/A
cycles
1.
These values are based on simulation. These values are not covered by test limits in production or characterization.
42.6.1.2
Crystal Oscillator Characteristics
The following table describes the characteristics for the oscillator when a crystal is connected
between XIN and XOUT as shown in Figure 42-3. The user must choose a crystal oscillator
where the crystal load capacitance C_L is within the range given in the table. The exact value of C_L
can be found in the crystal datasheet. The capacitance of the external capacitors (C_LEXT) can
then be computed as follows:
C_LEXT = 2(C_L – C_STRAY–C_SHUNT)
where C_STRAY is the capacitance of the pins and PCB, C_SHUNT is the shunt capacitance of the
crystal.
Table 42-20. Crystal Oscillator Characteristics
Symbol
f_OUT
Parameter
Crystal oscillator frequency ⁽¹⁾
Conditions
Min
0.6
f = 0.455MHz, C_LEXT = 100pF
SCIF.OSCCTRL.GAIN = 0
f = 2MHz, C_LEXT = 20pF
SCIF.OSCCTRL.GAIN = 0
ESR
Crystal Equivalent Series Resistance ⁽²⁾
f = 4MHz, C_LEXT = 20pF
SCIF.OSCCTRL.GAIN = 1
f = 8MHz, C_LEXT = 20pF
SCIF.OSCCTRL.GAIN = 2
f = 16MHz, C_LEXT = 20pF
SCIF.OSCCTRL.GAIN = 3
f = 30MHz, C_LEXT = 18pF
SCIF.OSCCTRL.GAIN = 4
Typ
Max
Unit
30
MHz
17000
2000
1500
Ω
300
350
45
42023C–SAM–02/2013
1125