1°C Temperature Sensor with Beta Compensation
Datasheet
Chapter 4 System Management Bus Interface Protocol
4.1
System Management Bus Interface Protocol
TheEMC1402 communicates with a host controller, such as an SMSC SIO, through the SMBus. The
SMBus is a two-wire serial communication protocol between a computer host and its peripheral
devices. A detailed timing diagram is shown in Figure 4.1.
For the first 15ms after power-up the device may not respond to SMBus communications.
.
TLOW
THIGH
THD:STA
TSU:STO
TRISE
TFALL
SMCLK
TSU:STA
THD:STA
THD:DAT
TSU:DAT
SMDTA
TBUF
S
S
P
P - Stop Condition
P
S - Start Condition
Figure 4.1 SMBus Timing Diagram
The EMC1402 is SMBus 2.0 compatible and support 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 4.1.
Table 4.1 Protocol Format
DATA SENT
TO DEVICE
DATA SENT TO
THE HOST
# of bits sent
# of bits sent
Attempting to communicate with the EMC1402 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.
4.2
Write Byte
The Write Byte is used to write one byte of data to the registers as shown below Table 4.2:
Table 4.2 Write Byte Protocol
SLAVE
ADDRESS
REGISTER
ADDRESS
REGISTER
DATA
START
WR
ACK
ACK
ACK
STOP
1 -> 0
1001_100
0
0
XXh
0
XXh
0
0 -> 1
Revision 2.0 (08-10-12)
SMSC EMC1402
DATA1S2HEET
SMSC [ SMSC CORPORATION ]
