ATSAM3U-EK Atmel, ATSAM3U-EK Datasheet - Page 1118

• Manufacturer Part Number: ATSAM3U-EK
• Description: KIT EVAL FOR AT91SAM3U CORTEX
• Manufacturer: Atmel
• Type: MCUr

Specifications of ATSAM3U-EK

• Contents: Board
• Processor To Be Evaluated: SAM3U
• Data Bus Width: 32 bit
• Interface Type: RS-232, USB
• Operating Supply Voltage: 3 V
• Silicon Manufacturer: Atmel
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: SAM3U4E
• Silicon Family Name: SAM3U
• Kit Contents: Board CD Docs
• Rohs Compliant: Yes
• For Use With/related Products: AT91SAM3U
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

43.4.9
43.4.9.1
43.4.9.2
1118
SAM3U Series
Crystal Oscillators Design Consideration Information
Choosing a Crystal
Printed Circuit Board (PCB)
When choosing a crystal for the 32768 Hz Slow Clock Oscillator or for the 3-20 MHz Oscillator,
several parameters must be taken into account. Important parameters between crystal and
SAM3U specifications are as follows:
SAM3U Oscillators are low power oscillators requiring particular attention when designing PCB
systems. A board design example is given on Atmel’s website in the MCU Technical Center
Section.
• Load Capacitance
• Drive Level
• Equivalent Series Resistor (ESR)
• Shunt Capacitance
– This is the equivalent capacitor value the oscillator must “show” to the crystal in
– Crystal drive level >= Oscillator Drive Level. Having a crystal drive level number
– Crystal ESR <= Oscillator ESR Max. Having a crystal with ESR value higher than
– Max. crystal Shunt capacitance <= Oscillator Shunt Capacitance (
order to oscillate at the target frequency. Crystal must be chosen according to the
internal load capacitance (C
load capacitance will result in a frequency drift.
lower than the oscillator specification may damage the crystal.
the oscillator may cause the oscillator to not start.
Having a crystal with ESR value higher than the oscillator may cause the
oscillator to not start.
L
)of the on-chip oscillator. Having a mismatch for the
6430D–ATARM–25-Mar-11
C
SHUNT
).