Fan Control Device with High Frequency PWM and Temperature Monitors
Datasheet
Table 5.2 SMBus Write Byte Protocol
FIELD
Bits
START
SLAVE ADDR
WR
ACK
REG. ADDR
ACK
REG. DATA
ACK
STOP
1
7
1
1
8
1
8
1
1
Read Byte
The Read Byte protocol is used to read data from the registers. The data will only be read if the
protocol shown in Table 5.3 is performed correctly. Only one byte is transferred at time for a Read Byte
protocol.
Table 5.3 SMBus Read Byte Protocol
SLAVE
ADDR
REG.
ADDR
SLAVE
ADDR
REG.
DATA
FIELD:
START
WR
ACK
ACK
START
RD
ACK
NACK
STOP
1
7
1
1
8
1
1
7
1
1
8
1
1
Bits:
5.4
Invalid Protocol Response Behavior
Registers that are accessed with an invalid protocol will not be updated. A register will only be updated
following a valid protocol. The only valid protocols are the Write Byte and Read Byte protocols, which
are described above.
The EMC2300 device responds to three SMBus slave addresses:
1. The SMBus slave address that supports the valid protocols defined in the previous sections is
determined by the level on the Address Select and Address Enable pins as shown in Section 5.1,
"Slave Address," on page 15.
2. SMBus Alert Response (0001 100). The SMBus will only respond to the SMBus Alert Response
Address if the SMBus Alert Response interrupt was generated to request a response from the Host.
The SMBus Alert Response is defined in Section 5.10, "SMBus Alert Response Address," on
page 18.
Attempting to communicate with the Hardware Monitor Block over SMBus with an invalid slave
address, or invalid protocol will result in no response, and the SMBus Slave Interface will return to the
idle state.
The only valid registers that are accessible by the SMBus slave address are the registers defined in
the Registers Section. See Section 5.4.1, "Undefined Registers" for response to undefined registers.
5.4.1
Undefined Registers
Reads to undefined registers return 00h. Writes to undefined registers have no effect and return no
error.
5.5
5.6
General Call Address Response
The EMC2300 will not respond to a general call address of 0000_000.
Slave Device Time-Out
The EMC2300 supports the slave device timeout as per the SMBus Specification, v2.0.
SMSC EMC2300
Revision 0.2 (06-14-06)
DATA1S7HEET
SMSC [ SMSC CORPORATION ]
