at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 254

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

25.5
Figure 25-4. Divider and PLL Block Diagram
25.5.1
Figure 25-5. PLL Capacitors and Resistors
6221G–ATARM–31-Jan-08
Divider and PLL Block
PLL Filter
MAINCK
The PLL embeds an input divider to increase the accuracy of the resulting clock signals. How-
ever, the user must respect the PLL minimum input frequency when programming the divider.
Figure 25-4
The PLL requires connection to an external second-order filter through the PLLRCA and/or PLL-
RCB pin.
Values of R, C1 and C2 to be connected to the PLLRC pin must be calculated as a function of
the PLL input frequency, the PLL output frequency and the phase margin. A trade-off has to be
found between output signal overshoot and startup time.
SLCK
Figure 25-5
shows the block diagram of the divider and PLL blocks.
C2
shows a schematic of these filters.
C1
R
Divider B
Divider A
DIVB
DIVA
PLLRC
GND
PLLRCA
MULB
MULA
PLLBCOUNT
PLLACOUNT
PLL
Counter
Counter
PLL B
PLL A
PLL B
PLL A
OUTB
OUTA
LOCKA
LOCKB
AT91SAM9260
PLLBCK
PLLACK
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