+/+…when timing is critical
C9819
133 MHz I2C Clock Generator for Mobile Pentium®III / Rambus Systems
Preliminary
ACK
ACK
SDATA IS OUTPUT PIN
COMMAND BYTE
(DON'TCARE)
1
1
0
1
0
0
1
0
SDATA IS INPUT PIN
SDATA
MSB
LSB
SCLK
8
START CONDITION
CONTINUED
ACK
ACK
ACK
COUNT BYTE
(DON'TCARE)
BYTE 0
(VALID DATA)
BYTE N (LAST
VALID DATA)
CONTINUED
8
8
8
STOP CONDITION
Fig.5
Serial Control Registers
NOTE: The Pin# column lists the affected pin number where applicable. The @Pup column gives the state at true
power up. Bytes are set to the values shown only on true power up, and not when the PWR_DWN# pin is activated.
Following the acknowledge of the Address Byte (D2), two additional bytes must be sent:
1) “Command Code “ byte, and
2) “Byte Count” byte.
Although the data (bits) in these two bytes are considered “don’t care”, they must be sent and will be acknowledged.
Byte 0: Function Select Register
Bit
7
6
5
4
3
2
1
0
@Pup
Pin#
Description
Reserved
SST2* (see table6, p.8)
SST1* (see table6, p.8)
SST0* (see table6, p.8)
Reserved
0
1
1
1
0
0
0
0
*
*
*
*
*
*
Reserved
Bit1 Bit0
1
1
0
0
1
0
1
0
Tri-State (all outputs)
Spread Spectrum enabled
Test Mode (see table 3)
NON spread spectrum operating mode
INTERNATIONAL MICROCIRCUITS, INC 525 LOS COCHES ST.
MILPITAS, CA 95035, USA TEL: 408-263-6300 FAX 408-263-6571
Rev 1.0
11/1/1999
Page 6 of 17
http://www.imicorp.com
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