参数资料
型号: SL28506BZIT
厂商: Silicon Laboratories Inc
文件页数: 5/28页
文件大小: 0K
描述: IC CLOCK CK505 PCIE GEN2 64TSSOP
标准包装: 2,000
类型: 时钟/频率发生器
PLL:
主要目的: Intel CPU 服务器
输入: 时钟,晶体
输出: HCSL,LVCMOS
电路数: 1
比率 - 输入:输出: 1:22
差分 - 输入:输出: 无/是
频率 - 最大: 400MHz
电源电压: 3.135 V ~ 3.465 V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 64-TFSOP (0.240",6.10mm 宽)
供应商设备封装: 64-TSSOP
包装: 带卷 (TR)
SL28506
.......................DOC #: SP-AP-0021 (Rev AA) Page 13 of 28
Dial-A-Frequency (CPU andSRC)
This feature allows the user to over-clock their system by
slowly stepping up the CPU or SRC frequency. When the
programmable output frequency feature is enabled, the CPU
and SRC frequencies are determined by the following
equation:
Fcpu = G * N/M or Fcpu=G2 * N, where G2 = G / M.
“N” and “M” are the values programmed in Programmable
Frequency Select N-Value Register and M-Value Register,
respectively.
“G” stands for the PLL Gear Constant, which is determined
by the programmed value of FS[E:A]. See Table 1,
Frequency Select Table for the Gear Constant for each
Frequency selection. The PCI Express only allows user
control of the N register, the M value is fixed and
documented in Table 1, Frequency Select Table.
In this mode, the user writes the desired N and M values into
the DAF I2C registers. The user cannot change only the M
value and must change both the M and the N values at the
same time, if they require a change to the M value. The user
may change only the N value.
Associated Register Bits
CPU_DAF Enable – This bit enables CPU DAF mode. By
default, it is not set. When set, the operating frequency is
determined by the values entered into the CPU_DAF_N
register. Note that the CPU_DAF_N and M register must
contain valid values before CPU_DAF is set. Default = 0,
(No DAF).
CPU_DAF_N – There are nine bits (for 512 values) to
linearly change the CPU frequency (limited by VCO range).
Default = 0, (0000). The allowable values for N are detailed
in Table 1, Frequency Select Table.
CPU DAF M – There are 7 bits (for 128 values) to linearly
change the CPU frequency (limited by VCO range). Default
= 0, the allowable values for M are detailed in Table 1,
Frequency Select Table
SRC_DAF Enable – This bit enables SRC DAF mode. By
default, it is not set. When set, the operating frequency is
determined by the values entered into the SRC_DAF_N
register. Note that the SRC_DAF_N register must contain
valid values before SRC_DAF is set. Default = 0, (No DAF).
SRC_DAF_N – There are nine bits (for 512 values) to
linearly change the CPU frequency (limited by VCO range).
Default = 0, (0000). The allowable values for N are detailed
in Table 1, Frequency Select Table.
Smooth Switching
The device contains one smooth switch circuit that is shared
by the CPU PLL and SRC PLL. The smooth switch circuit
ensures that when the output frequency changes by
overclocking, the transition from the old frequency to the new
frequency is a slow, smooth transition containing no glitches.
The rate of change of output frequency when using the smooth
switch circuit is less than 1 MHz/0.667
s. The frequency
overshoot and undershoot is less than 2%.
The Smooth Switch circuit assigns auto or manual. In Auto
mode, clock generator assigns smooth switch automatically
when the PLL does overclocking. For manual mode, assign
the smooth switch circuit to PLL via Smbus. By default the
smooth switch circuit is set to auto mode. PLL can be
over-clocked when it does not have control of the smooth
switch circuit but it is not guaranteed to transition to the new
frequency without large frequency glitches.
Do not enable over-clocking and change the N values of both
PLLs in the same SMBUS block write and use smooth switch
mechanism on spread spectrum on/off.
PD_RESTORE
If a ‘0’ is set for Byte 0 bit 0 then, upon assertion of PD# LOW,
the SL28506 initiates a full reset. The result of this is that the
clock chip emulates a cold power on start and goes to the
“Latches Open” state. If the PD_RESTORE bit is set to a ‘1’
then the configuration is stored upon PD# asserted LOW. Note
that if the iAMT bit, Byte 0 bit 3, is set to a ‘1’ then the
PD_RESTORE bit must be ignored. In other words, in Intel
iAMT mode, PD# reset is not allowed.
PD# (Power down) Clarification
The CKPWRGD/PD# pin is a dual-function pin. During initial
power up, the pin functions as CKPWRGD. Once CKPWRGD
has been sampled HIGH by the clock chip, the pin assumes
PD# functionality. The PD# pin is an asynchronous active
LOW input used to shut off all clocks cleanly before shutting
off power to the device. This signal is synchronized internally
to the device before powering down the clock synthesizer. PD#
is also an asynchronous input for powering up the system.
When PD# is asserted LOW, clocks are driven to a LOW value
and held before turning off the VCOs and the crystal oscillator.
PD# (Power down) Assertion
When PD is sampled HIGH by two consecutive rising edges
of CPUC, all single-ended outputs will be held LOW on their
next HIGH-to-LOW transition and differential clocks must held
LOW. When PD mode is desired as the initial power on state,
PD must be asserted HIGH in less than 10
s after asserting
CKPWRGD.
Table 6. Output Driver Status
All Single-ended Clocks
All Differential Clocks except
CPU1
w/o Strap
w/ Strap
Clock
Clock#
Clock
Clock#
Latches Open State
Low
Hi-z
Low or 20K pulldown
Low
Low or 20K pulldown Low
Powerdown
Low
Hi-z
Low or 20K pulldown
Low
Low or 20K pulldown Low
M1
Low
Hi-z
Low or 20K pulldown
Low
Running
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