EMC1001 datasheet(11/16 Pages) SMSC

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1.5°C SMBus Temperature Sensor in Miniature SOT-23

Datasheet

SMSC EMC1001

Revision 1.6 (01-29-07)

DATASHEET

“B” shows the bit position of a 16-bit word created by concatenating the High Byte and Low Byte, and

the lower case “b” shows the bit position in the 10-bit value.

4.3

ALERT/THERM2 Output

The ALERT/THERM2 output asserts if an out of limit measurement is detected (TA

≤ low limit or TA >

high limit). The ALERT/THERM2 pin is an open drain output and requires a pull up resistor to VDD.The

ALERT

/THERM2 pin can be used as an SMBALERT#, or may be configured as a second THERM output.

As described in the SMBus specification, an SMBus slave may inform the SMBus master that it wants

to talk by asserting the SMBALERT# signal. One or more ALERT outputs can be hardwired together

as a wired-or bus to a common input.

The ALERT/THERM2 pin resets when the EMC1001 responds to an alert response address (ARA=0001

100) sent by the host, and if the out of limit condition no longer exists, but it does not reset if the error

condition remains. The ALERT/THERM2 pin can be masked so that it will not assert in the event of an

out of limit temperature measurement, except when it is configured as a second THERM pin.

Figure 4.3 ALERT Response to Temperature Limits Exceeded

The ALERT/THERM2 pin can be configured as a second THERM pin that asserts when the temperature

measurement exceeds the Temperature High Limit value. In this mode, the output will not de-assert

until the temerature drops below the Temperature High Limit minus the THERM Hysteresis value.

4.4

ADDR/THERM Output

The ADDR/THERM output asserts if the temperature measurement exceeds the programmable THERM

limit. It can be used to drive a fan or other failsafe devices. The ADDR/THERM pin is open drain and

requires a pull up resistor to VDD. The value of this pull up resistor determines the slave address per

Table 1.2 on page 3. The ADDR/THERM pin cannot be masked.

When the ADDR/THERM pin is asserted, it will not de-assert until the temperature drops below the

THERM limit minus the THERM hysteresis value.

Table 4.2 Bit Position of Two Byte Values

HIGH BYTE

LOW BYTE

B15

B14

B13

B12

B11

B10

Temp

Time

Temperature High Limit

Temperature Low Limit

ALERT/THERM2

Logic High

Logic

Level

SMBus ARA

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