ICS950812 Datasheet, PDF (22/30 Pages) Integrated Circuit Systems – Frequency Generator with 200MHz Differential CPU Clocks

ICS950812
Frequency Generator with 200MHz Differential CPU Clocks
BYTE
13
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Pin #
X
X
X
X
X
X
X
X
Affected Pin
Name
-
-
-
-
-
-
-
-
Control Function
Spread Spectrum Bit7
Spread Spectrum Bit6
Spread Spectrum Bit5
Spread Spectrum Bit4
Spread Spectrum Bit3
Spread Spectrum Bit2
Spread Spectrum Bit1
Spread Spectrum Bit0
Type
RW
RW
RW
RW
RW
RW
RW
RW
Bit Control
0
1
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
PWD
X
X
X
X
X
X
X
X
Note: Please utilize software utility provided by ICS Application Engineering to configure spread spectrum. Incorrect spread
percentage may cause system failure.
BYTE
14
Bit 7
Pin #
X
Affected Pin
Name
-
Control Function
(Reserved)
Type
RW
Bit Control
0
1
-
-
PWD
X
Bit 6
X
-
Bit 5
X
-
Bit 4
X
-
Bit 3
X
-
Bit 2
X
-
Bit 1
X
-
Bit 0
X
-
(Reserved)
Spread Spectrum Bit13
Spread Spectrum Bit12
Spread Spectrum Bit11
Spread Spectrum Bit10
Spread Spectrum Bit9
Spread Spectrum Bit8
RW
-
RW
-
RW
-
RW
-
RW
-
RW
-
RW
-
-
X
-
X
-
X
-
X
-
X
-
X
-
X
Note: Please utilize software utility provided by ICS Application Engineering to configure spread spectrum. Incorrect spread
percentage may cause system failure.
Note: See table 8 for Byte 11-14 default information
Spread Spectrum Enable Procedure
Step 1: Power-up ---- Latched inputs, FS(5:0), set frequency per Hardware default on board. SS is off.
BIOS program set IIC Byte0, bit7 to 1, SS will be enable Spread. Note that Byte 10,
bit 7 is default to 0. This allows all setup to be controlled by the Frequency Select
Tables, 1 and 2.
Step 2: After power up, SS% can be changed to the fixed selections shown in Frequency Table 2. This
is achieved by Writing to Byte 4, bit 6/7 (FS5:4) and/or Byte 0 (FS3), The data written
to these bytes will overwrite the existing contents and switch to the desired selection.
Step 3: To set up Linear programming and SS% adjust using Byte 11 through 14, the BIOS must
set
Byte 10, bit 7 to a 1. This will enable access to Byte 11 and 12, M/N linear programming
and Byte 13 and 14, Spread Spectrum % adjust.
IDT^TM Frequency Generator with 200MHz Differential CPU Clocks
22
0542J—01/25/10