f75387 Feature Integration Technology Inc., f75387 Datasheet - Page 17

• Manufacturer Part Number: f75387
• Description: ?1o C Accuracy H/w Monitor Ic With Automatic Fan Speed Control
• Manufacturer: Feature Integration Technology Inc.

(a). When PWMOUT duty-cycle decrease to MIN_DUTY(≠ 00h), obviously the duty-cycle will decrease to 00h next,
the F75387 will keep duty-cycle at 00h for 1.6 seconds. After that, the F75387 starts to compare current fan count
and expected count in order to increase or decrease its duty-cycle. This ensures that if there is any glitch during the
period, the F75387 will ignore it.
6.12.
Fan_Fault# will be asserted when the fan speed doesn’t meet the expected fan speed within a programmable period
(default is 11 seconds) or when fan stops with respect to PWM duty-cycle which should be able to turn on the fan.
There are two conditions may cause the FAN_FAULT# event.
(1). When PWM_Duty reaches FFh, the fan speed count can’t reach the fan expected count in time. (Figure 6-3)
(2). After the period of detecting fan full speed, when PWM_Duty > Min. Duty, and current fan count is monitored
FFFFh.
6.13. SMI#
Temperature
SMI# interrupt for temperature is shown as figure 6-4. There are two types of temperature SMI# interrupt.
1. Temperature exceeding high limit or going below hystersis will cause an interrupt if the previous interrupt has been
reset by writing “1” all the interrupt Status Register.
FAN
_Fault#
Expected Fan Count
Current Fan Count
Fan_Fault#
Duty-cycle
Start Duty
Stop Duty
100%
15
11 sec(default)
Figure 6-3
July, 2007
F75387
0.27P