SAM3N0C Atmel Corporation, SAM3N0C Datasheet - Page 36

• Manufacturer Part Number: SAM3N0C
• Manufacturer: Atmel Corporation

9.5
36
Clock Generator
SAM3N Summary
The reset circuitry is based on a zero-power power-on reset cell and a brownout detector cell.
The zero-power power-on reset allows the Supply Controller to start properly, while the soft-
ware-programmable brownout detector allows detection of either a battery discharge or main
voltage loss.
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 sequentially enabling the internal power switches
and 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 9-2.
• One Low Power 32768Hz Slow Clock Oscillator with bypass mode
• One Low-Power RC Oscillator
• One 3-20 MHz Crystal or Ceramic resonator Oscillator, which can be bypassed
• One Fast RC Oscillator factory programmed, 3 output frequencies can be selected: 4, 8 or 12
• One 60 to 130 MHz programmable PLL, capable to provide the clock MCK to the processor
MHz. By default 4 MHz is selected.
and to the peripherals. The input frequency of PLL is from 3.5 to 20 MHz.
Clock Generator Block Diagram
XOUT32
XIN32
XOUT
XIN
Clock Generator
On Chip 32 kHz
PLL and
Divider A
Slow Clock
Management
12/8/4 MHz
3-20 MHz
Oscillator
Oscillator
On Chip
RC OSC
Controller
RC OSC
Status
Main
Power
Control
XTALSEL
Slow Clock
SLCK
Main Clock
MAINCK
MAINSEL
PLLA Clock
PLLACK
11011AS–ATARM–04-Oct-10