C9630 Datasheet, PDF (9/18 Pages) Cypress Semiconductor – PC133 Clock Generator for SiS630/Pentium III & SiS540/Socket7 Applications

APPROVED PRODUCT
C9630
PC133 Clock Generator for SiS630/Pentium^®III & SiS540/Socket7 Applications
Dial-a-Frequency^™ Feature (Cont.)
Since this N number must be entered in Binary, it can only be an integer, so it must be rounded up or down. Here we
can rounded it up to 71, which will give us an exact CPU frequency of:
Fcpu = 96016000 X N = 145.045 MHz (accuracy + 310 ppm)
47
If the above frequency is not accurate enough, then you must choose another R value and start from the beginning. For
example choose R = 49 and this will yield an N = 73.99808365, which is rounded to 74. If the 74 is applied in the
formula 1, then Fcpu = 145.0038 MHz (accuracy + 26 ppm).
Other R values within the above limits may also be evaluated.
SMBus Communication Waveform
IMI Device _ACK
ACK
ACK
Master Device _{1 1 0 1 0 0 1 0 COMMAND BYTE}
BYTE COUNT
BYTE 0
SDATA
MSB
(Don’t Care)
LSB
(Don’t Care)
(Valid)
ACK
BYTE N
(Valid)
ACK
SCLK
Master Device
SDATA
8
8
START
Fig.6a (WRITE)
IMI Device _{ACK BYTE COUNT}
BYTE 0
11010011
MSB
LSB
(Valid)
ACK
(Valid)
8
8
STOP CONDITION
BYTE1
ACK
(Valid)
ACK
BYTE N
(Valid)
NO ACK
SCLK
START CONDITION
8
8
Fig.6b (READ)
8
8
STOP CONDITION
Cypress Semiconductor Corporation
525 Los Coches St.
Milpitas, CA 95035. Tel: [phone], Fax: [phone]
http://www.cypress.com
Document#: 38-07035 Rev. **
05/02/2001
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