W83697HF/F
9.3.3 Temperature Measurement Machine
The temperature data format is 8-bit two's-complement for sensor 1 and 9-bit two's-complement for
sensor 2. The 8-bit temperature data can be obtained by reading the CR[27h]. The 9-bit temperature data
can be obtained by reading the 8 MSBs from the Bank1 CR[50h] and the LSB from the Bank1 CR[51h]
bit 7. The format of the temperature data is show in Table 1.
Temperature
8-Bit Digital Output
8-Bit Binary 8-Bit Hex
9-Bit Digital Output
9-Bit Binary
9-Bit Hex
0FAh
032h
°
+125 C
0111,1101
0001,1001
0000,0001
-
7Dh
19h
01h
-
0,1111,1010
0,0011,0010
0,0000,0010
0,0000,0001
0,0000,0000
1,1111,1111
1,1111,1110
1,1100,1110
1,1001,0010
°
+25 C
°
+1 C
002h
°
+0.5 C
001h
°
+0 C
0000,0000
-
00h
-
000h
°
-0.5 C
1FFh
1FFh
1CEh
192h
°
-1 C
1111,1111
1110,0111
1100,1001
FFh
E7h
C9h
Table 2.
°
-25 C
°
-55 C
9.3.3.1 Monitor temperature from thermistor:
The W83697HF can connect three thermistors to measure three different envirment temperature. The
b
specification of thermistor should be considered to (1) value is 3435K, (2) resistor value is 10K ohms at
°
25 C. In the Figure 9.2, the themistor is connected by a serial resistor with 10K Ohms, then connect to
VREF (Pin 101).
9.3.3.2 Monitor temperature from Pentium IITM thermal diode or bipolar transistor 2N3904
The W83697HF can alternate the thermistor to Pentium IITM (Deschutes) thermal diode interface or
transistor 2N3904 and the circuit connection is shown as Figure 9.3. The pin of Pentium IITM D- is
connected to power supply ground (GND) and the pin D+ is connected to pin VTINx in the W83697HF.
The resistor R=30K ohms should be connected to VREF to supply the diode bias current and the
bypass capacitor C=3300pF should be added to filter the high frequency noise. The transistor 2N3904
should be connected to a form with a diode, that is, the Base (B) and Collector (C) in the 2N3904 should
be tied togeter to act as a thermal diode.
Publication Release Date: Feb. 2002
- 87 -
Revision 0.70
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