Datasheet
59.4.9 Crystal Oscillator Design Considerations
59.4.9.1 Choosing a Crystal
When choosing a crystal for the 32768 Hz Slow Clock Oscillator or for the 3 MHz–20 MHz oscillator, users need to
consider several parameters. Important parameters between crystal and product specifications are as follows:
•
Crystal Load Capacitance
– The total capacitance loading the crystal, including the oscillator’s internal parasitics and the PCB
parasitics, must match the load capacitance for which the crystal’s frequency is specified. Any mismatch in
the load capacitance with respect to the crystal’s specification will lead to inaccurate oscillation frequency.
• Drive Level
– Crystal drive level ≥ Oscillator Drive Level. Having a crystal drive level number lower than the oscillator
specification may damage the crystal.
• Equivalent Series Resistor (ESR)
– Crystal ESR ≤ Oscillator ESR Max. Having a crystal with ESR value higher than the oscillator may cause
the oscillator to not start.
• Shunt Capacitance
– Max. crystal shunt capacitance ≤ Oscillator Shunt Capacitance (C
SHUNT
). Having a crystal with C
SHUNT
value higher than the oscillator may cause the oscillator to not start.
59.4.9.2 Printed Circuit Board (PCB)
To minimize the inductive and capacitive parasitics associated with XIN, XOUT, XIN32 and XOUT32 nets, it is
recommended to route them as short as possible. Additionally, it is important to keep these nets away from noisy
switching signals (clock, data, PWM, and so on), and shield them with a quiet ground net to avoid coupling to
neighboring signals.
59.5 PLLA Characteristics
Table 59-26. PLLA Characteristics
Symbol Parameter Conditions Min. Typ. Max. Unit
f
IN
Input Frequency – 8 – 32 MHz
f
OUT
Output Frequency – 160 – 500 MHz
I
PLL
Current Consumption Active mode at 160 MHz at 1.2V – 2.2 3 mA
Active mode at 500 MHz at 1.2V – 8 12
t
ST
ART
Startup Time – – – 300 µs
59.6 PLLUSB Characteristics
Table 59-27. PLLUSB Characteristics
Symbol Parameter Conditions Min. Typ. Max. Unit
f
IN
Input Frequency – – 12 or 16 – MHz
f
OUT
Output Frequency – – 480 – MHz
I
PLLUSB
Current Consumption In Active mode, on VDDPLLUSB – 4.9 6.4 mA
In Active mode, on VDDCORE – 0.4 1 mA
t
ST
ART
Startup Time – – – 50 µs
SAM E70/S70/V70/V71 Family
Electrical Characteristics for SAM E70/S70
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 1877