ATSAM3U_10 ATMEL [ATMEL Corporation], ATSAM3U_10 Datasheet - Page 39

• Manufacturer Part Number: ATSAM3U_10
• Description: AT91ARM Cortex M3-based Microcontrollers
• Manufacturer: ATMEL [ATMEL Corporation]

10.5
6430CS–ATARM–09-Apr-10
Clock Generator
The Slow Clock generator is based on a 32 kHz crystal oscillator and an embedded 32 kHz RC
oscillator. The Slow Clock defaults to the RC oscillator, but the software can enable the crystal
oscillator and select it as the Slow Clock source.
The Supply Controller starts up the device by enabling the Voltage Regulator, then it generates
the proper reset signals to the core power supply.
It also enables to set the system in different low power modes and to wake it up from a wide
range of events.
The Clock Generator is made up of:
Figure 10-2. Clock Generator Block Diagram
• One Low Power 32768 Hz Slow Clock Oscillator with bypass mode
• One Low Power RC Oscillator
• One 3 to 20 MHz Crystal Oscillator, which can be bypassed
• One Fast RC Oscillator factory programmed, 3 output frequencies can be selected: 4, 8 or 12
• One 480 MHz UPLL providing a clock for the USB High Speed Device Controller. Input
• One 96 to 192 MHz programmable PLL (PLL A), capable to provide the clock MCK to the
MHz. By default 4 MHz is selected. 8 MHz and 12 MHz output are factory calibrated.
frequency is 12 MHz (only).
processor and to the peripherals. The input frequency of the PLL A is between 8 and 16 MHz.
XOUT32
XIN32
XOUT
XIN
Management
Clock Generator
32k RC OSC
Slow Clock
12M Main
12/8/4 MHz
Controller
Status
Oscillator
Oscillator
PLL and
Divider A
On Chip
On Chip
RC OSC
Power
Divider
PLL B
/6 /8
Control
XTALSEL
Slow Clock
SLCK
Main Clock
MAINCK
MAINSEL
HSCK
UPLL Clock
UPLLCK
PLLA Clock
PLLACK
SAM3U Series
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