EMC1413 datasheet(14/52 Pages) SMSC

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Multiple Channel 1°C Temperature Sensors with Beta Compensation

Datasheet

Revision 1.41 (02-23-12)

SMSC EMC1413 / EMC1414

DATASHEET

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.

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.

15k

1101_100(r/w)b

22k

0011_100(r/w)b

33k

0111_100(r/w)b

Figure 5.2 Isolating THERM Pin

Table 5.1 SMBus Address Decode (continued)

PULL UP RESISTOR ON

THERM PIN (±5%)

SMBUS ADDRESS

EMC1413 /

EMC1414

SMDATA

SMCLK

ALERT

VDD

DP1

DN1

THERM / ADDR

GND

+3.3V

Shared Therm

22K

4.7K – 33k

+2.5 - 5V

DP2 / DN3

DN2 / DP3

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