ICS9250BF-27LFT IDT, Integrated Device Technology Inc, ICS9250BF-27LFT Datasheet - Page 5

• Manufacturer Part Number: ICS9250BF-27LFT
• Description: IC FREQ GENERATOR/BUFFER 56-SSOP
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Frequency Generatorr

Specifications of ICS9250BF-27LFT

• Frequency - Max: 133MHz
• Voltage - Supply: 3.135 V ~ 3.465 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 56-SSOP
• Frequency-max: 133MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output: -
• Input: -
• Other names: 9250BF-27LFT

IDT
Byte 3: ICS Reserved Functionality and frequency select register (Default as noted in PWD)
Note 1: For system operation, the BSEL lines of the CPU will program FS0, FS2 for the appropriate CPU speed, always
Note 2: "ICS RESERVED BITS" must be writtern as "O".
Note3: Undefined bits can be written either as "1 or 0"
Byte 2: Control Register
(1 = enable, 0 = disable)
Notes:
1. Inactive means outputs are held LOW and are disabled from switching. These outputs are designed to be
2. PWD = Power on Default
3. Undefined bit can be wirtten with either a "1" or "0".
ICS9250-27
Frequency Generator and Integrated Buffers for Celeron & PII/III
TM
B
B
B
B
B
B
B
B
configured at power-on and are not expected to be configured during the normal modes of operation.
B
B
i B
i B
i B
i B
i B
i B
i B
B
t i
t i
t i
t i
t i
t i
t i
t i
Frequency Generator and Integrated Buffers for Celeron & PII/III
t i
t i
t i
7 t
6 t
5 t
4 t
3 t
2 t
7
6
5
4
3
2
0
1 t
1
0
with SDRAM = 100MHz. After BIOS verifies the SDRAM is PC133 speed, then bit 0 can be written from the
default 0 to 1 to change the SDRAM output frequency from 100MHz to 133MHz. This will only change if the CPU
is at the 133MHz FSB speed as shown in this table. The CPU, 3v66, PCI, and IOAPIC clocks will be glitch free
during this transition, and only SDRAM will change.
P
C I
C I
C I
C I
C I
U
U
2
1
1
1
1
1
n i
9
-
d n
d n
B
0
9
8
6
5
3
S
S
S
S
S
#
t i
0
0
0
0
1
1
1
1
f e
f e
R
R
R
R
R
0
n i
n i
e
e
e
e
e
e s
e s
e s
e s
e s
3
P
P
P
P
P
P
U
d e
d e
V
C
C
C
C
C
C
n
v r
v r
v r
v r
v r
6
d
C I
C I
C I
C I
C I
C I
i b
i b
d e
d e
d e
d e
d e
6
f e
2 -
L
L
L
L
L
L
( t
( t
F
N
n i
K
K
K
K
K
K
i b
i b
i b
i b
i b
S
0
0
0
0
1
1
1
1
N
N
a
e
A (
0
5
4
3
2
1
0
( t
( t
( t
( t
( t
m
d
o
o
G
e t
e t
N
N
N
N
N
e
b
) P
t i
o
o
o
o
o
) 3
) 3
e t
e t
e t
e t
e t
F
) 2
) 2
) 2
) 2
) 2
S
0
0
0
0
1
1
1
1
1
P
W
X
1
1
1
1
1
1
1
D
C
P
3 1
3 1
3 1
3 1
6
1
6
1
M
U
A (
A (
A (
A (
A (
A (
A (
A (
. 6
. 6
0 0
0 0
. 3
. 3
. 3
. 3
D
H
C
6 6
6 6
c
c
c
c
c
c
c
c
0 .
2 3
2 3
0 .
2 3
2 3
e
D
z
L
v i t
v i t
v i t
v i t
v i t
v i t
v i t
v i t
c s
K
e
/ e
/ e
/ e
/ e
/ e
/ e
/ e
/ e
i t
s
c
t p
n I
n I
n I
n I
n I
n I
n I
n I
i r
S
o i
a
a
a
a
a
a
a
a
3 1
3 1
3 1
D
t p
1
1
1
1
1
M
c
c
c
c
c
c
c
c
n
0 0
0 0
0 0
0 0
0 0
R
. 3
. 3
. 3
v i t
v i t
v i t
v i t
v i t
v i t
v i t
v i t
o i
H
A
TM
0 .
0 .
2 3
0 .
0 .
0 .
2 3
2 3
z
n
) e
) e
) e
) e
) e
) e
) e
) e
M
5
TM
3
6
6
6
6
6
6
6
6
M
. 6
. 6
. 6
. 6
. 6
. 6
. 6
. 6
V
H
6 6
6 6
6 6
6 6
6 6
6 6
6 6
6 6
6 6
z
P
C
3
3
3
3
3
3
3
3
M
C I
. 3
. 3
. 3
. 3
. 3
. 3
. 3
. 3
H
3 3
3 3
3 3
3 3
3 3
3 3
3 3
3 3
L
z
K
I
O
3
3
3
3
3
3
3
3
M
A
. 3
. 3
. 3
. 3
. 3
. 3
. 3
. 3
H
P
3 3
3 3
3 3
3 3
3 3
3 3
3 3
3 3
z
C I
N
P
o
W
X
X
0
0
0
0
0
0
e t
D
1
0395F—01/25/10