ICS9148-93 查看數據表（PDF） - Integrated Circuit Systems
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ICS9148-93 Datasheet PDF : 14 Pages
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ICS9148 - 93
Advance Information
General I2C serial interface information
The information in this section assumes familiarity with I2C programming. For more information, contact ICS for an I2C
programming application note.
How to Write:
Send the address D2(H) .
Send two additional dummy bytes, a command code
and byte count.
Send the desired number of data bytes.
See the diagram below:
Clock Generator
Address (7 bits)
A(6:0) & R/W#
D2(H)
+ 8 bits
ACK
dummy
ACK
command code
+ 8 bits
dummy Byte
count
ACK
Data Byte
1
ACK
Data Byte
N
ACK
Note that the acknowledge bit is sent by the clock chip, and pulls the data line low. There is no minimum of data bytes that must
be sent.
How to Read:
Send the address D3(H).
Send the byte count in binary coded decimal
Read back the desired number of data bytes
See the diagram below:
Clock Generator
Address (7 bits)
A(6:0) & R/W#
ACK
Byte
Count
ACK
Data Byte
1
ACK
Data Byte
N
D3(H)
The following specifications should be observed:
1. Operating voltage for I2C pins is 3.3V
2. Maximum data transfer rate (SCLK) is 100K bits/sec.
Note 1. Default at Power-up will be for latched logic inputs,
as defined by Bit 3.
I2C is a trademark of Philips Corporation
Serial Configuration Command Bitmap
Byte0: Functionality and Frequency Select Register
(default = 0)
Bit
Bit 7
Bit
6:4
Bit 3
Bit 1
Bit 0
Description
0 - ±0.25% Spread Spectrum Modulation
1 - ±0.6% Spread Spectrum Modulation
Bit (6:4)
CPU
SDRAM
(MHz)
PCI
(MHz)
AGP
(MHz)
000
90.00
30.00
60.00
001
66.82
33.41 66.82
010
68.49
34.25
68.49
011
75.00
37.50
75.00
100
75.00
30.00
60.00
101
83.31
33.32
66.64
110
95.25
31.75
63.50
111
100.00
33.33
66.66
0 - Frequency is selected by hardware select,
FS(0:2) pins only
1 - Select frequencies by I2C
0 - Center Spread
1 - Down Spread
0 - Normal operation
1 - Spread Spectrum Enabled
0 - Running
1- Tristate all outputs
PWD
0
XXX
Note 1
0
0
0
0
4
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