ICS842S104 Datasheet, PDF (3/21 Pages) Integrated Device Technology – Crystal-to-HSTL 100MHz / 200MHz PCI Express™ Clock Synthesizer

ICS842S104 Data Sheet
CRYSTAL-TO- HSTL 100MHZ / 200MHZ PCI EXPRESS™ CLOCK SYNTHESIZER
Serial Data Interface
To enhance the flexibility and function of the clock synthesizer, a
two-signal I²C serial interface is provided. Through the Serial Data
Interface, various device functions, such as individual clock output
buffers, can be individually enabled or disabled. The registers
associated with the serial interface initialize to their default setting
upon power-up, and therefore, use of this interface is optional. Clock
device register changes are normally made upon system
initialization, if any are required.
Data Protocol
The clock driver serial protocol accepts byte write, byte read, block
write and block read operations from the controller. For block
write/read operation, the bytes must be accessed in sequential order
from lowest to highest byte (most significant bit first) with the ability to
stop after any complete byte has been transferred. For byte write and
byte read operations, the system controller can access individually
indexed bytes. The offset of the indexed byte is encoded in the
command code, as described in Table 3A.
The block write and block read protocol is outlined in Table 3B, while
Table 3C outlines the corresponding byte write and byte read
protocol. The slave receiver address is 11010010 (D2h).
Table 3A.Command Code Definition
Bit
Description
7
0 = Block read or block write operation, 1 = Byte read or byte write operation.
6:5
Chip select address, set to “00” to access device.
4:0
Byte offset for byte read or byte write operation. For block read or block write operations, these bits must be “00000”.
ICS842S104CG REVISION A MARCH 17, 2010
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