f75334 Feature Integration Technology Inc., f75334 Datasheet - Page 20

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

Fan speed control
And the suggested application circuit for linear fan control would be:
evaluated by the following equation. As for fan, it would be best to use 2 pulses tachometer
output per round.
Linear Fan Control
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:
PWM duty Fan Control
set to 100%, that is, the default 8-bit registers is set to FFh. The expression of duty can be
The F75334DG provides 2 fan speed control methods:
The range of DC output is 0~3.3V, controlled by 8-bit register. 1 LSB is about 0.013V.
The duty cycle of PWM can be programmed by a 8-bit register. The default duty cycle is
DC OUTPUT VOLTAGE
1. LINEAR FAN CONTROL 2. PWM DUTY CYCLE
3.9K
Output_vol
R
3
2
12V
+
-
tage
LM358
(V)
DC FAN Control with OP
1
R 10K
=
3
Fig 7-9
3 .
PMOS
×
RPM
13
Programmed
C
47u
=
1 ×
JP1
CON3
5 .
Count
3
2
1
10
1N4148
6
8bit
255
D1
Register
C
0.1u
R
4.7K
Value
R 27K
R
10K
FANIN MONITOR
F75334
July, 2007
V0.25P