High-Side Current-Sense and Internal 1°C Temperature Monitor
Datasheet
Table 3.1 ADDR_SEL Resistor Setting (continued)
RESISTOR (5%)
SMBUS ADDRESS
RESISTOR (5%)
SMBUS ADDRESS
560
750
1001_001(r/w)
1001_010(r/w)
1001_011(r/w)
9100
20000
Open
0101_100(r/w)
0101_101(r/w)
0011_000(r/w)
1270
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
3.1.3
SMBus ACK and NACK Bits
The SMBus client will acknowledge all data bytes that it receives (as well as the client address if it
matches and the ARA address if the ALERT pin is asserted). This is done by the client device pulling
the SMBus Data line low after the 8th bit of each byte that is transmitted.
The host will NACK (not acknowledge) the data received from the client by holding the SMBus data
line high after the 8th data bit has been sent.
3.1.4
3.1.5
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 EMC1701 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.
SMBus Time-out
The EMC1701 includes an SMBus time-out feature. Following a 30ms period of inactivity on the
SMBus, the device will time-out and reset the SMBus interface.
The time-out functionality defaults to disabled and can be enabled by writing to the TIMEOUT bit (see
Section 5.11).
2
3.1.6
SMBus and I C Compliance
The major differences between SMBus and I2C devices are highlighted here. For complete compliance
information, refer to the SMBus 2.0 specification.
1. Minimum frequency for SMBus communications is 10kHz.
2. The client protocol will reset if the clock is held at a logic ‘0’ for longer than 30ms. This time-out
functionality is disabled by default.
3. The client protocol will reset if both the clock and data lines are held at a logic ‘1’ for longer than
150us. This function is disabled by default.
4. I2C devices do not support the Alert Response Address functionality (which is optional for SMBus).
Revision 1.2 (09-27-10)
SMSC EMC1701
DATA1S6HEET
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