Datasheet

System Clock Domains
Intel
®
Atom™ Processor E6xx Series Datasheet
51
4.0 System Clock Domains
The Intel
®
Atom™ Processor E6xx Series contains many clock frequency domains to
support its various interfaces.
Table 34 summarizes these domains.
§ §
Table 34. Intel
®
Atom™ Processor E6xx Series Clock Domains
Clock
Domain
Signal Name Frequency Source Usage
Processor BCLKP/BCLKN 100 MHz
Main clock
generator
Processor reference clock
Processor
HPLL_REFCLK_P
HPLL_REFCLK_N
100 MHz
Main clock
generator
Processor reference clock
CLK14 CLK14 14.31818 MHz
Main clock
generator
Used by 8254 timers and HPET. It
runs at 14.31818 MHz. This clock
stops during S3, S4, and S5
states.
PCI Express*
PCIE_CLKINP
PCIE_CLKINN
100 MHz
Main clock
generator
PCI Express* ports
Display
reference clock
SDVO_REFCLKP
SDVO_REFCLKN
96 MHz
Main clock
generator
Primary clock source for display
clocks and Intel
®
High Definition
Audio
β
RTC
RTCX1
RTCX2
32.768 KHz Crystal oscillator
RTC and power management.
Always running
Derivative Clocks
(These are clock domains that are fractional multiples of existing clock frequencies.)
DDR2
M_CKP
M_CKN
400 MHz From Host PLL
Drives SDRAM ranks 0 and 1.
Data Rate is 2x the clock rate.
LVDS
LVD_CLKP
LVD_CLKN
20 MHz -
80 MHz
From Display PLL LVDS display clock outputs
SDVO
SDVO_CLKP
SDVO_CLKN
100 MHz -
160 MHz
From Display PLL SDVO display clock outputs
LPC LPC_CLKOUT[2:0] Up to 33 MHz From CRU
Supplied for external devices
requiring PCICLK
Intel
®
HD
Audio
β
HDA_CLK 24 MHz From CRU Drives external codecs
SMBus SMB_CLK Up to 1 MHz From CRU Drives external SMBus device
SPI SPI_SCLK 20/33 MHz From CRU Drives external SPI flash device