W83627EHF_0611 Datasheet, PDF (34/144 Pages) Winbond – WINBOND LPC I/O

W83627EHF/EF, W83627EHG/EG
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^TM/Pentium III^TM thermal diode and
the circuit connection is shown as Figure 6.3. The pin of Pentium II^TM/ Pentium III^TM D- is connected to
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.
R=15K,1%
Pentium II/III/IV
CPU
D+
Therminal
Diode
D-
C=2200pF
AGND
VREF
W83627EHF
CPUTIN
AGND
Figure 6.3
6.4 FAN Speed Count and FAN Speed Control
6.4.1 Fan speed count
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:
Count = ^{1.35 ×106}
RPM × Divisor
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.
RPM = ^{1.35 × 106}
Count × Divisor
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