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Clocking
Copyright © 2008 Marvell Doc. No. MV-S104859-U0 Rev. E
December 2, 2008, Preliminary Document Classification: Proprietary Information Page 61
The following table lists the supported combinations of the CPU_CLK Frequency select, CPU_CLK
to DDR CLK ratio, and to CPU_CLK to CPU L2 clock ratio (see Section 6.5, Pins Sample
Configuration, on page 66).
SATA PHY PLL
• Reference clock:
REF_CLK_XIN (25 MHz)
• Derivative clock:
SATA Clock (150 MHz)
RTC
• Reference clock:
RTC_XIN (32.768 kHz)
Used for real time clock functionality, see the Real Time Clock section in the
88F6180, 88F6190, 88F6192, and 88F6281 Functional Specifications.
PTP
• Reference clock:
PTP_CLK (125 MHz)
The PTP_CLK can be used for the following functions:
• PTP time stamp clock
Two options for reference clock:
- PTP_CLK
- Gigabit Ethernet Clock (125 MHz)
• TS unit clock
Two options for reference clock:
- PTP_CLK/2
- Core PLL
• Audio unit clock
Two options for reference clock:
- PTP_CLK
- REF_CLK_XIN (25 MHz)
For clocking configuration registers, see the 88F6180, 88F6190, 88F6192, and
88F6281 Functional Specifications.
Table 30: Supported Clock Combinations
DDR Clock
(MHz)
CPU to DDR
Clock Ratio
CPU Clock
(MHz)
CPU to L2
Clock Ratio
L2 Clock
(MHz)
333
250
200
3:1
4:1
5:1
1000 3:1 333
400
300
267
200
3:1
4:1
4.5:1
6:1
1200 3:1 400
375 4:1 1500 3:1 500
Table 29: 88F6281Clocks (Continued)
Clock Type Description