W83L786NR Datasheet, PDF (17/50 Pages) Winbond – H/W Monitoring IC

W83L786NR/ W83L786NG
7.5.3 Temperature Fault (TEMP_FAULT #)
W83L786NR/NG provides a good protection for temperature fault. Set Pin 2 (TEMP_FAULT#) to
monitor temperature. When D+-D- (Pin12, 11), or VTIN1 (Pin10) temperature exceeds temperature
fault limit in VR35 or VR37, Pin 2 TEMP_FAULT# will be asserted (Figure 6).
T E M P _ F A U L T lim it
TEM P_FA U LT#
F ig u re 6 . T E M P _ F A U L T
7.6 FAN Speed Count and FAN Speed Control
7.6.1 Fan Speed Count
Inputs are provided by the signals from fans equipped with tachometer outputs. The level of these
signals should be set to TTL level, and maximum input voltage cannot be over V_CC. If the input signals
from the tachometer outputs are over the V_CC, the external trimming circuit should be added to reduce
the voltage to obtain the input specification. The normal circuit and trimming circuits are shown in
Figure 7.
Determine the fan counter according to:
1.35 × 10⁶
Count = _{RPM × Divisor}
In other words, the fan speed counter has been read from register VR28 or VR29, and the fan speed
can be evaluated by the following equation.
1.35 × 10⁶
RPM = _{Count × Divisor}
The default divisor is 2 and defined at CR54.bit0~2, bit4~6 which are three bits for divisor. That
provides very low speed fan counter such as power supply fan. Table 2 is an example for the relation
of divisor, RPM, and count.
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