W83791D Information Storage Devices, Inc, W83791D Datasheet - Page 32

• Manufacturer Part Number: W83791D
• Description: Hardware Monitor With Speech Synthesizer And Asf Functions
• Manufacturer: Information Storage Devices, Inc

6.8
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 bank0 CR[C0/ C8h] and the LSB from the bank0 CR[C1/C9h] bit 7. The format of
the temperature data is show in Table 3.
6.8.1 Monitor temperature from thermistor:
specification of thermistor should be considered to (1)
the Figure 11, the themistor is connected by a serial resistor with 10K Ohms(1% error), then connect to VREF (Pin
37).
6.8.2 Monitor temperature from Pentium II
and the circuit connection is shown as Figure 11. The pin of Pentium II/III
ground (GND) and the pin D+ is connected to pin PIITDx in the W83791D. 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 together to act as a thermal diode.
Temperature
+125°C
+25°C
+1°C
+0.5°C
+0°C
-0.5°C
-1°C
-25°C
-55°C
The temperature data format is 8-bit two-complement for sensor 1 and 9-bit two-complement for sensor 2/3.
The W83791D can connect three thermistors to measure three different environmental temperatures. The
The W83791D can alternate the thermistor to Pentium II/III
Temperature Measurement Machine
8-Bit Digital Output
8-Bit Binary
0111,1101
0001,1001
0000,0001
-
0000,0000
-
1111,1111
1110,0111
1100,1001
TM
8-Bit Hex
7Dh
19h
01h
-
00h
-
FFh
E7h
C9h
thermal diode or bipolar transistor 2N3904
Table 3.
25
value is 3435K, (2) resistor value is 10K ohms at 25 C. In
TM
9-Bit Digital Output
9-Bit Binary
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
thermal diode interface or transistor 2N3904
Publication Release Date: Aug, 2001
TM
D- is connected to power supply
9-Bit Hex
0FAh
032h
002h
001h
000h
1FFh
1FFh
1CEh
192h
W83791D
Preliminary
Revision 0.41