f75375 Feature Integration Technology Inc., f75375 Datasheet - Page 14

• Manufacturer Part Number: f75375
• Description: Fintek Hardware Monitor Ic Datasheet
• Manufacturer: Feature Integration Technology Inc.

6.3.1
The F75375S provides 2 fan speed control methods:
The range of DC output is 0~3.3V, controlled by 8-bit register (CR76 for FAN1 and CR86 for FAN2). 1 LSB is about 0.013V.
The output DC voltage is amplified by external OP circuit, thus to reach maximum FAN OPERATION VOLTAGE, 12V.
The output voltage will be given as followed:
Determine the fan counter according to:
In other words, the fan speed counter has been read from register, the fan speed can be evaluated by the following equation.
As for fan, it would be best to use 2 pulses tachmeter output per round.
6.3.1.1 Linear Fan Control
Fintek
Fan speed control
Figure 5-5 Fan with Tach Pull-Up to +12V, or Totern-Pole
Figure 5-7. Fan with Tach Pull-Up to +5V, or Totern-Pole
FAN Out
FAN Out
+5V
GND
+12V
GND
+5V
+12V
Output and Register Attenuator
Output and Register Attenuator
Pull-up resister
4.7K Ohms
Pull-up resister
4.7K Ohms
1K~2.7K
22K~30K
Fan Input
Fan Input
10K
10K
FANIN1
F75375S
FANIN 1
F75375S
Count
RPM
1. LINEAR FAN CONTROL
8
=
=
1 ×
1 ×
5 .
Count
5 .
Connector
RPM
Connector
Feature Integration Technology Inc.
FAN
Figure 5-6 Fan with Tach Pull-Up to +12V, or
FAN
.Figure 5-8 Fan with Tach Pull-Up to +5V, or
10
10
FAN Out
FAN Out
6
+12V
GND
6
+5V
GND
+12V
+5V
Totem-Pole Putput and Zener Clamp
Totem-Pole Putput and Zener Clamp
F75375S/F75375SG
Pull-up resister < 1K
or totem-pole output
2. PWM DUTY CYCLE
Pull-up resister < 1K
or totem-pole output
3.3V Zener
3.3V Zener
> 1K
> 1K
Fan Input
Fan Input
FANIN 1
F75375S
FANIN1
F75375S
July 2007
V0.26P