Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features
Datasheet
Address Decided
Start
0
1
0
1
1
SDA
SCL
First five address bits
Figure 5.1 Address Selection on EMC6D103
5.2
5.3
Slave Bus Interface
The EMC6D103 device SMBus implementation is a subset of the SMBus interface to the host. The
device is a slave-only SMBus device. The implementation in the device is a subset of SMBus since it
only supports Write Byte and Read Byte protocols.
The Write Byte and Read Byte protocols are valid SMBus protocols for the device. This part responds
to other protocols as described in the Invalid Protocol Section. Reference the System Management
Bus Specification, Rev 2.0.
The SMBus interface is used to read and write the registers in the device. The register set is shown
in Chapter 8, "Register Set," on page 49.
Bus Protocols
Typical Write Byte and Read Byte protocols are shown below. Register accesses are performed using
7-bit slave addressing, an 8-bit register address field, and an 8-bit data field. The shading indicates
the Hardware Monitor Block driving data on the SDA line; otherwise, host data is on the SDA line.
The slave address is the unique SMBus Interface Address for the Hardware Monitor Block that
identifies it on SMBus. The register address field is the internal address of the register to be accessed.
The register data field is the data that the host is attempting to write to the register or the contents of
the register that the host is attempting to read.
Note: Data bytes are transferred MSB first.
Byte Protocols
A write byte transfer will always consist of the SMBus Interface Address byte, followed by the Internal
Address Register byte, then the data byte.
The normal read protocol consists of a write to the Hardware Monitor Block with the SMBus Interface
Address byte, followed by the Internal Address Register byte. Then restart the Serial Communication
with a Read consisting of the SMBus Interface Address byte, followed by the data byte read from the
Hardware Monitor Block. This can be accomplished by using the Read Byte protocol.
Write Byte
The Write Byte protocol is used to write data to the registers. The data will only be written if the protocol
shown in Table 5.2 is performed correctly. Only one byte is transferred at time for a Write Byte protocol.
SMSC EMC6D103
Revision 0.4 (04-04-05)
DATA1S9HEET
SMSC [ SMSC CORPORATION ]
