AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 44

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Figure 20. Clock Tree Diagram
CPU and Peripheral Clocks
44
XTAL2
XTAL1
AT8xC5122/23
PCON.1
PD
CK_XTAL1
Two clocks sources are available for CPU and peripherals:
These clock sources are configured by the PR1 prescaler to generate the CPU core
CK_CPU and the peripheral clocks:
PLLCON.1
96 MHz
PLLEN
PLL
–
–
–
–
–
–
–
–
on-chip oscillator
a derivative of the PLL clock.
CK_IDLE for alternate card and peripherals registers access
CK_T0 for Timer 0
CK_T1 for Timer 1
CK_SI for the UART
CK_WD for the Watchdog Timer
CK_SPI for SPI
CK_XTAL1
CK_PLL
CK_PLL
CKSEL.0
CKS
1/2
0
1
DCCKPS[3:0]
CKRL[3:0]
PLLCON.2
PR1
SCICLK.7
XTSCS
EXT48
PR4
CK_PLL
CK_XTAL1
CK_XTAL1
1/2
CKCON0.X or
CKCON0.0
PeriphX2
CKCON1.0
0
1
X2
0
1
0
1
1
0
SCICLK[5:0]
CKCON0.0
PERIPH = T0, T1, SI, WD or SPI
CK_IDLE
PR2
X2
1
0
SCSR[3:2]
PCON.0
PR3
IDL
SCICLK[5:0]
<48
=48
CK_PERIPH
CK_DCDC
CK_IDLE
CK_IDLE
CK_CPU
CK_USB
CK_ISO
4202D–SCR–06/05
Peripherals
Converter
Alternate
CK_T0
CK_T1
CK_SI
CK_WD
CK_SPI
DC/DC
SCIB
Card
CPU
USB