SAM3X8C Atmel Corporation, SAM3X8C Datasheet - Page 534

• Manufacturer Part Number: SAM3X8C
• Manufacturer: Atmel Corporation

28.1.3
28.1.4
534
534
SAM3X/A
SAM3X/A
Block Diagram
Slow Clock
Figure 28-1. Clock Generator Block Diagram
The Supply Controller embeds a slow clock generator that is supplied with the VDDBU power
supply. As soon as the VDDBU is supplied, both the crystal oscillator and the embedded RC
oscillator are powered up, but only the embedded RC oscillator is enabled. This allows the slow
clock to be valid in a short time (about 100 μs).
The Slow Clock is generated either by the Slow Clock Crystal Oscillator or by the Slow Clock RC
Oscillator.
The selection between the RC or the crystal oscillator is made by writing the XTALSEL bit in the
Supply Controller Control Register (SUPC_CR).
XOUT32
(Supply Controller)
XIN32
XOUT
XIN
XTALSEL
Clock Generator
RC Oscillator
12/8/4 MHz
Embedded
Management
Embedded
32 kHz RC
3-20 MHz
Oscillator
32768 Hz
Status
Oscillator
Oscillator
Crystal
Controller
Crystal
Fast
Power
Control
0
1
0
1
MOSCSEL
USB UTMI
PLLA and
Divider
PLL
Slow Clock
SLCK
Main Clock
MAINCK
PLLA Clock
PLLACK
UPLL Clock
UPLLCK
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12