Rainbow Electronics MAX34441 - Manual (Page 23)

PMBus 5-Channel Power-Supply Manager
and Intelligent Fan Controller
MAX34441
23
Table 7. Fan Control Operation Modes
Note: The RPM modes should only be used with fans that provide a tachometer output.
Figure 1. Automatic Fan Control
FAN CONTROL
MODE
FAN OPERATIONAL DETAILS
BIT 6 OF
FAN_CONFIG_1_2
VALUE IN
FAN_COMMAND_1
Manual PWM
External host controls the fan speed by directly setting the fan
PWM duty cycle values.
0 0000h to 7FFFh
Manual RPM
External host controls the fan speed by setting target fan speed
values. The device reads the actual fan speed, and close loop
adjusts the output fan PWM to match the target fan speed.
1 0000h to 7FFFh
Automatic PWM
The device sets the output PWM based on the fan LUT that
maps the temperature sensor readings to the required fan PWM
duty-cycle values.
0 8000h to FFFFh
Automatic RPM
The device reads the actual fan speed and close loop adjusts
the output fan PWM to match the target fan speed based on
the fan LUT that maps the temperature sensor readings to the
required fan speed.
1 8000h to FFFFh
I 2 C REMOTE
TEMP SENSOR 0
+15°C
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PAGE 6
I 2 C REMOTE
TEMP SENSOR 1
I 2 C REMOTE
TEMP SENSOR 2
I 2 C REMOTE
TEMP SENSOR 3
REMOTE DIODE
TEMP SENSOR
HIGHEST TEMPERATURE
CONTROLS THE FAN
INTERNAL
TEMP SENSOR
+10°C
0°C
0°C
+5°C
+5°C
FAN 8 LEVEL
LOOKUP TABLE
FAN
OFFSET ADJUSTMENT
ALLOWS TEMPERATURE
ZONE NORMALIZATION