Multiple Channel 1°C Temperature Sensors with Beta Compensation
Datasheet
Table 5.1 SMBus Address Decode (continued)
PULL UP RESISTOR ON
THERM PIN (±5%)
SMBUS ADDRESS
15k
22k
33k
1101_100(r/w)b
0011_100(r/w)b
0111_100(r/w)b
The EMC1413-1 SMBus address is hard coded to 1001_100(r/w).
The EMC1413-3 SMBus address is hard coded to 0011_000(r/w).
The EMC1414-1 SMBus address is hard coded to 1001_100(r/w).
5.1.3
THERM Pin Considerations
Because of the decode method used to determine the SMBus Address, it is important that the pull-up
resistance on the THERM pin be within the tolerances shown in Table 5.1. Additionally, the pull-up
resistor on the THERM pin must be connected to the same 3.3V supply that drives the VDD pin.
For 15ms after power up, the THERM pin must not be pulled low or the SMBus address will not be
decoded properly. If the system requirements do not permit these conditions, the THERM pin must be
isolated from its hard-wired OR’d bus during this time.
One method of isolating this pin is shown in Figure 5.2.
+3.3V
+2.5 - 5V
22K
4.7K – 33k
1
2
3
4
5
10
9
VDD
DP1
DN1
SMCLK
SMDATA
ALERT
EMC1413 /
EMC1414
8
Shared Therm
DP2 / DN3
DN2 / DP3
7
THERM / ADDR
GND
6
Figure 5.2 Isolating THERM Pin
5.1.4
SMBus Data Bytes
All SMBus Data bytes are sent most significant bit first and composed of 8-bits of information.
5.1.5
SMBus ACK and NACK Bits
The SMBus client will acknowledge all data bytes that it receives. This is done by the client device
pulling the SMBus data line low after the 8th bit of each byte that is transmitted. This applies to the
Write Byte protocol.
The Host will NACK (not acknowledge) the last data byte to be received from the client by holding the
SMBus data line high after the 8th data bit has been sent.
Revision 1.41 (02-23-12)
SMSC EMC1413 / EMC1414
DATA1S4HEET
SMSC [ SMSC CORPORATION ]
