Fan Control Device with High Frequency PWM and Temperature Monitors
Datasheet
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.
6.8.3
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)
Table 6.6, "Temperature Data Format" shows several examples of the format of the temperature digital
0
data, represented by an 8-bit, two’s complement word with an LSB equal to 1.0 C.
Table 6.6 Temperature Data Format
TEMPERATURE
READING (DEC)
READING (HEX)
DIGITAL OUTPUT
-1270C
-127
81h
1000 0001
0
-50 C
-50
-25
CEh
E7h
1100 1110
1110 0111
0
-25 C
0
-1 C
-1
0
FFh
00h
01h
1111 1111
0000 0000
0000 0001
0
0 C
0
+1 C
1
0
+25 C
25
50
19h
32h
0001 1001
0011 0010
+500C
+1270C
127
128
7Fh
80h
0111 1111
1000 0000
SENSOR ERROR
6.9
Thermal Zones
Each temperature measurement input is assigned to a Thermal Zone to control the PWM outputs in
Auto Fan Control mode. These zone assignments are as follows:
Zone 1 = Remote Diode 1 (Processor)
Zone 2 = Ambient (Internal) Temperature Sensor
Zone 3 = Remote Diode 2
Revision 0.2 (06-14-06)
SMSC EMC2300
DATA2S8HEET
SMSC [ SMSC CORPORATION ]
