Environmental Monitoring and Control Device
Datasheet
programmed limits in the Internal (Zone 2) High Temperature Limit register (51h) and the Internal (Zone 2)
Low Temperature Limit register (50h) the corresponding status bit in Interrupt Status Register 1 is set.
If auto fan option is selected, the hardware will adjust the operation of the fans accordingly. See section
7.4.2 Auto Fan Control Operating Mode.
6.9.2 EXTERNAL TEMPERATURE MEASUREMENT
The Hardware Monitor Block also provides a way to measure two external temperatures using diode
sensor pins (Remote x+ and Remote x-). The value is stored in the Processor (Zone 1) Temperature
Reading register (25h) for Remote1+ and Remote1- pins. The value is stored in the Remote (Zone 3)
Temperature Reading register (27h) for Remote2+ and Remote2- pins. If these values violate the
programmed limits in the associated limit registers, then Zone (1 or 3) Limit Exceeded status bit is set in
the Interrupt Status Register 1.
If auto fan option is selected, the hardware will adjust the operation of the fans accordingly. See section
7.4.2 Auto Fan Control Operating Mode on page 31.
There are Remote Diode (1 or 2) Fault status bits in Interrupt Status Register 2 (42h), which, when one,
indicate a short or open-circuit on remote thermal diode inputs (Remote x+ and Remote x-). Before a
remote diode conversion is updated, the status of the remote diode is checked. In the case of a short or
open-circuit on the remote thermal diode inputs, the value in the corresponding reading register will be
80h. Note that this will cause the associated zone limit exceeded status bit to be set.
The temperature change is computed by measuring the change in Vbe at two different operating points of
the diode to which the Remote x+ and Remote x- pins are connected. But accuracy of the measurement
also depends on non-ideality factor of the process the diode is manufactured on.
6.9.3 TEMPERATURE DATA FORMAT
Temperature data can be read from the three temperature registers. One is the Internal (Zone 2)
Temperature Reading register (26h), the second is the Processor (Zone 1) Temperature Reading register
(25h), and the third is the Remote (Zone 3) Temperature Reading register (27h).
The following table shows several examples of the format of the temperature digital data, represented by
0
an 8-bit, two’s complement word with an LSB equal to 1.0 C.
TEMPERATURE
READING (DEC)
READING (HEX)
DIGITAL OUTPUT
1000 0001
…
0
-127
…
-50
…
-25
…
-1
0
1
…
25
…
50
…
81h
…
CEh
…
E7h
-127 C
…
0
1100 1110
-50 C
…
…
0
1110 0111
…
1111 1111
0000 0000
0000 0001
…
-25 C
…
…
0
FFh
00h
01h
…
19h
…
-1 C
0
0 C
0
+1 C
…
0
0001 1001
+25 C
…
…
0
32h
…
0011 0010
…
+50 C
…
SMSC EMC6D100/EMC6D101
Page 27
Rev. 09-09-04
DATASHEET
SMSC [ SMSC CORPORATION ]
