ICS9DB423B
4-OUTPUT DIFFERENTIAL BUFFER FOR PCIE GEN1, GEN2, AND QPI
IDT®
4-OUTPUT DIFFERENTIAL BUFFER FOR PCIE GEN1, GEN2, AND QPI 11
ICS9DB423B REV E 091812
General SMBus Serial Interface Information
How to Write
• Controller (host) sends a start bit
• Controller (host) sends the write address DC
(h)
• IDT clock will acknowledge
• Controller (host) sends the beginning byte location = N
• IDT clock will acknowledge
• Controller (host) sends the byte count = X
• IDT clock will acknowledge
• Controller (host) starts sending Byte N through Byte
N+X-1
• IDT clock will acknowledge each byte one at a time
• Controller (host) sends a Stop bit
How to Read
• Controller (host) will send a start bit
• Controller (host) sends the write address DC
(h)
• IDT clock will acknowledge
• Controller (host) sends the beginning byte location = N
• IDT clock will acknowledge
• Controller (host) will send a separate start bit
• Controller (host) sends the read address DD
(h)
• IDT clock will acknowledge
• IDT clock will send the data byte count = X
• IDT clock sends Byte N+X-1
• IDT clock sends Byte 0 through Byte X (if X
(H)
was
written to Byte 8)
• Controller (host) will need to acknowledge each byte
• Controller (host) will send a not acknowledge bit
• Controller (host) will send a stop bit
Index Block Write Operation
Controller (Host) IDT (Slave/Receiver)
TstarT bit
Slave Address
DC
(h)
WR WRite
ACK
Beginning Byte = N
ACK
Data Byte Count = X
ACK
Beginning Byte N
X Byte
ACK
O
O O
O O
O
Byte N + X - 1
ACK
PstoP bit
Read Address Write Address
DD
(h)
DC
(h)
Index Block Read Operation
Controller (Host) IDT (Slave/Receiver)
TstarT bit
Slave Address
DC
(h)
WR WRite
ACK
Beginning Byte = N
ACK
RT Repeat starT
Slave Address
DD
(h)
RD ReaD
ACK
Data Byte Count=X
ACK
X Byte
Beginning Byte N
ACK
O
O O
O O
O
Byte N + X - 1
N Not acknowledge
PstoP bit
