w83627ef Winbond Electronics Corp America, w83627ef Datasheet - Page 34

• Manufacturer Part Number: w83627ef
• Description: Lpc Super I/o For Desktop & Server
• Manufacturer: Winbond Electronics Corp America

6.3.3.1. Monitor temperature from thermistor
The W83627EHF/EHG can connect three thermistors to measure three different environment
temperature. The specification of thermistor should be considered to (1) β value is 3435K, (2) resistor
value is 10K ohms at 25°C. In the Figure 6.2, the themistor is connected by a serial resistor with 10K
Ohms, then connect to VREF (pin 101).
6.3.3.2. Monitor temperature from Pentium IITM/Pentium IIITM thermal diode
The W83627EHF/EHG can alternate the thermistor to Pentium II
the circuit connection is shown as Figure 6.3. The pin of Pentium II
AGND(pin 117) and the pin D+ is connected to temperature sensor pin in the W83627EHF/EHG. The
resistor R=15K ohms should be connected to VREF to supply the diode bias current and the bypass
capacitor C=2200pF should be added to filter the high frequency noise.
6.4
6.4.1
Inputs are provides for signals from fans equipped with tachometer outputs. The level of these signals
should be set to TTL level, and maximum input voltage can not be over +3.3V. If the input signals from
the tachometer outputs are over the +3.3V, the external trimming circuit should be added to reduce
the voltage to obtain the input specification. The normal circuit and trimming circuits are shown as
Figure 6.4.
Determine the fan counter according to:
In other words, the fan speed counter has been read from register Bank0 Index 28h, 29h, 2Ah ,3Fh
and Bank5 53h, the fan speed can be evaluated by the following equation.
FAN Speed Count and FAN Speed Control
Fan speed count
Pentium II/III/IV
CPU
Therminal
Diode
D+
D-
Count
RPM
R=15K,1%
W83627EHF/EF, W83627EHG/EG
=
=
Count
Figure 6.3
RPM
AGND
C=2200pF
- 28 -
1 35 10
. 1
.
35
×
×
×
×
Divisor
Divisor
10
6
6
TM
VREF
CPUTIN
AGND
/Pentium III
TM
W83627EHF
/ Pentium III
TM
thermal diode and
TM
D- is connected to