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C9806I
I
2C Frequency Clock Generator for Mobile Pentium II Applications.
Preliminary
INTERNATIONAL MICROCIRCUITS, INC. 525 LOS COCHES ST.
Rev.1.0
4/25/2000
MILPITAS, CA 95035. TEL: 408-263-6300. FAX 408-263-6571
Page 6 of 14
http://www.imicorp.com
Serial Control Registers (Continued)
Byte 3: SDRAM Register (1 = Enable, 0 = Stopped)
Bit
@Pup
Pin#
Description
7
1
26
Reserved
6
1
27
Reserved
5
1
29
SDRAM5 Enable/Stopped
4
1
30
SDRAM4 Enable/Stopped
3
1
32
SDRAM3 Enable/Stopped
2
1
33
SDRAM2 Enable/Stopped
1
35
SDRAM1 Enable/Stopped
0
1
36
SDRAM0 Enable/Stopped
Byte 4: SDRAM Register (1 = Enable, 0 = Stopped)
Bit
@Pup
Pin#
Description
7x
-
Reserved
6x
-
Reserved
5x
-
Reserved
4x
-
Reserved
3x
-
Reserved
2x
-
Reserved
1x
-
Reserved
0x
-
Reserved
Byte 5: Peripheral Control (1 = Enable, 0 = Stopped)
Bit
@Pup
Pin#
Description
7
x
-
Reserved
6
x
-
Reserved
5
1
47
REF3 Enable/Stopped
4
1
45
REF2 Enable/Stopped
3x
-
Reserved
2
x
-
Reserved
1
REF1 Enable/Stopped
0
1
2
REF0 Enable/Stopped
* SST (0:2) are soft select pins used for setting the
Spread Spectrum width options. See Spread
Spectrum description next section.
Byte 6: Dial-a-Frequency
Register
Bit
@Pup
Pin#
Description
70
-
N7, MSB
60
-
N6
50
-
N5
40
-
N4
30
-
N3
20
-
N2
10
-
N1
0
-
N0, LSB
Byte 7: Dial-a-Frequency
Register
Bit
@Pup
Pin#
Description
7
0
-
Reserved
6
0
-
Reserved
50
-
R5
40
-
R4
30
-
R3
20
-
R2
10
-
R1
00
-
R0
Byte 8: Dial-a-Frequency
Register
Bit
@Pup
Pin#
Description
7
0
-
Enable I2C N values
6
0
-
Enable I2C R values
5
0
-
Reserved
4
0
-
Reserved
3
0
-
Reserved
2
0
-
Reserved
1
0
-
Reserved
0
-
Reserved
Dial-a-Frequency
Feature
I2C Dial-a-frequency feature is available in this device via bytes 6, 7 and 8.
These bytes allow the user to enter the N and R values that will enable them to program any CPU frequency desired
following the formula:
Equ.(1)
Where N and R values are programmed in binary into bytes 6 & 7 for N and byte 8 for R. See table below for min and
max allowed values.
R
N
P
Fcpu
×
=