EMC6D103_07 Datasheet, PDF (30/92 Pages) SMSC Corporation – Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features

6.9.3
Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features
Datasheet
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 forced to 80h. Note that this will cause the associated remote diode limit exceeded
status bit to be set (i.e. Remote Diode x Limit Error bits (D1 and D2) are located in the Interrupt Status
1 Register at register address 41h).
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.
Temperature Data Format
Temperature data can be read from the three temperature registers:
„ Internal Temp Reading register (26h)
„ Remote Diode 1 Temp Reading register (25h)
„ Remote Diode 2 Temp Reading register (27h)
The following table shows several examples of the format of the temperature digital data, represented
by an 8-bit, two’s complement word with an LSB equal to 1.0 ⁰C.
TEMPERATURE
-127⁰C
Table 6.6 Temperature Data Format
READING (DEC)
-127
READING (HEX)
81h
DIGITAL OUTPUT
1000 0001
-50 ⁰C
-50
CEh
1100 1110
-25 ⁰C
-25
E7h
1110 0111
-1 ⁰C
-1
0 ⁰C
0
+1 ⁰C
1
FFh
1111 1111
00h
0000 0000
01h
0000 0001
+25 ⁰C
25
19h
0001 1001
+50⁰C
50
32h
0011 0010
+127⁰C
127
SENSOR ERROR
128
7Fh
0111 1111
80h
1000 0000
Revision 0.3 (03-01-07)
30
DATASHEET
SMSC EMC6D103