Mfr_fan_config (f1h), Table 32. mfr_fan_config – Rainbow Electronics MAX34441 User Manual
Page 46
PMBus 5-Channel Power-Supply Manager
and Intelligent Fan Controller
MAX34441
46
MFR_FAN_CONFIG (F1h)
The MFR_FAN_CONFIG command is used with FAN_CONFIG_1_2 to configure the fan. See the FAN_CONFIG_1_2
description for more details on this command. Table 32 described the MFR_FAN_CONFIG command.
Table 32. MFR_FAN_CONFIG
BIT
BIT NAME
MEANING
15:13
FREQ[2:0]
The FREQ bits set the PWM frequency. Note: The device does not support pulse stretching.
FREQ2
FREQ1
FREQ0
PWM FREQUENCY
0
0
0
30Hz
0
0
1
50Hz
0
1
0
100Hz
0
1
1
150Hz
1
0
0
Reserved
1
0
1
Reserved
1
1
0
Reserved
1
1
1
25kHz
12
0
This bit always returns a 0.
11:10
HYS[1:0]
The HYS bits determine the amount of hysteresis the device uses to determine how far the tem-
perature must fall below the temperature level threshold programmed in the LUT before switch-
ing to the lower PWM/RPM value. The hysteresis should be set lower than the minimum differ-
ence between two adjacent temperature steps. These bits are ignored if automatic fan control is
disabled.
HSY1
HSY0
THERMAL HYSTERESIS (NC)
0
0
2
0
1
4
1
0
6
1
1
8
9
TSFO
0 = Ramp to 100% PWM duty cycle if temp sensor faults (automatic fan mode) or if no
FAN_COMMAND_1 update occurs (manual fan mode) in any 10s period.
1 = Temp sensor fault or update rate to FAN_COMMAND_1 is ignored. Operate at the last
updated PWM/RPM value.
Note 1: A temp sensor fault is a faulty temperature sensor reading, not an overtemperature fault.
Note 2: In automatic fan mode, if the TSFO bit is set to 1, the device ignores a sensor fault and
uses the remaining assigned temperature sensors (if any) to control the fan PWM duty cycle; or,
if the fan has no available temperature sensors to use, it maintains the last updated PWM/RPM
fan value before the fault occurred.
8
TACHO
0 = Ramp fan to 100% PWM duty cycle if fan fault is detected.
1 = Do not ramp fan to 100% PWM duty cycle if fan fault is detected.
Note: If the fan fault is removed after ramping the PWM to 100% duty cycle, normal fan opera-
tion is resumed.