Multiple Channel 1°C Temperature Sensor with Beta Compensation
Datasheet
5.1.6
SMBus Stop Bit
The SMBus Stop bit is defined as a transition of the SMBus Data line from a logic ‘0’ state to a logic
‘1’ state while the SMBus clock line is in a logic ‘1’ state. When the device detects an SMBus Stop bit
and it has been communicating with the SMBus protocol, it will reset its client interface and prepare
to receive further communications.
5.1.7
5.1.8
SMBus Timeout
The EMC1412 supports SMBus Timeout. If the clock line is held low for longer than 30ms, the device
will reset its SMBus protocol. This function can be enabled by setting the TIMEOUT bit in the
Consecutive Alert Register (see Section 7.11).
2
SMBus and I C Compatibility
The EMC1412 is compatible with SMBus and I2C. The major differences between SMBus and I2C
devices are highlighted here. For more information, refer to the SMBus 2.0 and I2C specifications. For
information on using the EMC1412 in an I2C system, refer to SMSC AN 14.0 SMSC Dedicated Slave
Devices in I2C Systems.
1. EMC1412 supports I2C fast mode at 400kHz. This covers the SMBus max time of 100kHz.
2. Minimum frequency for SMBus communications is 10kHz.
3. The SMBus client protocol will reset if the clock is held at a logic ‘0’ for longer than 30ms. This
timeout functionality is disabled by default in the EMC1412 and can be enabled by writing to the
TIMEOUT bit. I2C does not have a timeout.
4. I2C devices do not support the Alert Response Address functionality (which is optional for SMBus).
Attempting to communicate with the EMC1412 SMBus interface with an invalid slave address or invalid
protocol will result in no response from the device and will not affect its register contents. Stretching
of the SMCLK signal is supported, provided other devices on the SMBus control the timing.
5.2
SMBus Protocols
The device supports Send Byte, Read Byte, Write Byte, Receive Byte, and the Alert Response Address
as valid protocols as shown below.
All of the below protocols use the convention in Table 5.2.
Table 5.2 Protocol Format
DATA SENT
TO DEVICE
DATA SENT TO
THE HOST
# of bits sent
# of bits sent
5.2.1
Write Byte
The Write Byte is used to write one byte of data to the registers, as shown in Table 5.3.
Table 5.3 Write Byte Protocol
SLAVE
ADDRESS
REGISTER
ADDRESS
REGISTER
DATA
START
1 -> 0
WR
ACK
ACK
ACK
STOP
YYYY_YYY
0
0
XXh
0
XXh
0
0 -> 1
SMSC EMC1412
Revision 1.41 (02-23-12)
DATA1S5HEET
SMSC [ SMSC CORPORATION ]
