f75334 Feature Integration Technology Inc., f75334 Datasheet - Page 22

• Manufacturer Part Number: f75334
• Description: Performance Controller
• Manufacturer: Feature Integration Technology Inc.

PWMOUT Duty-cycle operating process
FAN_FAULT#
duty-cycle according to current fan count and expected fan count. It will operate as follows:
fan.
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.
In both “Manual RPM” and “Temperature RPM” modes, the F75334DG adjust PWMOUT
(1). When expected count is 0xFFF, PWMOUT duty-cycle will be set to 0x00 to turn off
(3). If both (1) and (2) are not true,
Fan_Fault# will be asserted when the fan speed doesn’t meet the expected fan speed
(1). When PWM_Duty reaches 0xFF, the fan speed count can’t reach the fan expected
(2). When expected count is 0x000, PWMOUT duty-cycle will be set to 0xFF to turn on
(4). When PWMOUT duty-cycle decrease to MIN_DUTY(≠ 00h), obviously the
75 Degree C
65 Degree C
55 Degree C
45 Degree C
fan with full speed.
duty-cycle will decrease to 00h next, the F75334DG will keep duty-cycle at 00h for
1.6 seconds. After that, the F75334DG 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 F75334DG will ignore it.
Start Duty
Stop Duty
Figure 7-11
15
Fig 7-12
Desired Counts
0100h
0200h
0300h
0400h
0500h
F75334
July, 2007
V0.25P