MAX31785ETL+ Maxim Integrated Products, MAX31785ETL+ Datasheet - Page 30

• Manufacturer Part Number: MAX31785ETL+
• Description: Board Mount Temperature Sensors 6Ch Intelligent Fan Controller
• Manufacturer: Maxim Integrated Products

Specifications of MAX31785ETL+

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Table 14. PWM Fan Mode (FAN_CONFIG_1_2 Bit 6 = 0)
Table 15. RPM Fan Mode (FAN_CONFIG_1_2 Bit 6 = 1)
6-Channel Intelligent Fan Controller
The FAN_COMMAND_1 command is used to override the device’s automatic fan-control function and force the fan to
either a fixed PWM duty-cycle value or a target fan speed (in RPM). The units of FAN_COMMAND_1 are either percent
duty cycle (if bit 6 of FAN_CONFIG_1_2 is zero) or RPM (if bit 6 of FAN_CONFIG_1_2 is one). Any value less than 0%
duty cycle or 0 RPM causes the device to ignore this command and use the automatic fan-control function. Any value
greater than or equal to 0% duty cycle or 0 RPM causes the device to ignore the automatic fan-control function and
force the fan to the PWM value or RPM value provided by the FAN_COMMAND_1 command. The 2 data bytes are in
DIRECT format.
The VOUT_OV_FAULT_LIMIT command sets the value of the output voltage that causes an output overvoltage fault.
The monitored voltage must drop by at least 2% below the limit before the fault is allowed to clear. The 2 data bytes
are in DIRECT format. In response to the VOUT_OV_FAULT_LIMIT being exceeded, the device does the following:
1) Sets the VOUT_OV bit in STATUS_BYTE.
2) Sets the VOUT_OV and VOUT bits in STATUS_WORD.
3) Sets the VOUT_OV_FAULT bit in STATUS_VOUT.
4) Responds as specified in the MFR_FAULT_RESPONSE.
5) Notifies the host through ALERT assertion (if enabled in MFR_MODE).
The VOUT_OV_WARN_LIMIT command sets the value of the output voltage that causes an output-voltage high warn-
ing. This value is typically less than the output overvoltage threshold in VOUT_OV_FAULT_LIMIT. The monitored volt-
age must drop by at least 2% below the limit before the warning is allowed to clear. The 2 data bytes are in DIRECT
format. In response to the VOUT_OV_WARN_LIMIT being exceeded, the device does the following:
1) Sets the NONE OF THE ABOVE bit in STATUS_BYTE.
2) Sets the NONE OF THE ABOVE and VOUT bits in STATUS_WORD.
3) Sets the VOUT_OV_WARN bit in STATUS_VOUT.
4) Notifies the host using ALERT assertion (if enabled in MFR_MODE).
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FAN_COMMAND_1 VALUE
FAN_COMMAND_1 VALUE
8000h to FFFFh
0000h to 2710h
2711h to 7FFFh
8000h to FFFFh
0000h to 7FFFh
Ignore FAN_COMMAND_1 and use automatic fan-control function
0 to 100% fan PWM duty cycle
100% fan PWM duty cycle
Ignore FAN_COMMAND_1 and use automatic fan-control function
0 to 32,767 RPM
DEVICE RESPONSE
DEVICE RESPONSE
VOUT_OV_FAULT_LIMIT (40h)
VOUT_OV_WARN_LIMIT (42h)
FAN_COMMAND_1 (3Bh)