MAX31785ETL+ Maxim Integrated Products, MAX31785ETL+ Datasheet - Page 20

• 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

6-Channel Intelligent Fan Controller
Table 3. PMBus Command Code Coefficients
The host system uses the following equation to convert
the value received from the PMBus device—in this case,
the MAX31785—into a reading of volts, degrees Celsius,
or other units as appropriate:
where X is the calculated, real world value in the appro-
priate units (V, NC, etc.); m is the slope coefficient; Y is
the 2-byte, two’s complement integer received from the
PMBus device; b is the offset; and R is the exponent.
To send a value, the host must use the below equation
to solve for Y:
where Y is the 2-byte, two’s complement integer to be
sent to the unit; m is the slope coefficient; X is the real
world value, in units such as volts, to be converted for
transmission; b is the offset; and R is the exponent.
20
Voltage Scaling
PARAMETER
Temperature
Fan Speed
Voltage
Sending a DIRECT Format Value
X = (1/m) x (Y x 10 -
Y = (mX + b) x 10
VOUT_OV_FAULT_LIMIT
VOUT_OV_WARN_LIMIT
VOUT_UV_WARN_LIMIT
VOUT_UV_FAULT_LIMIT
READ_VOUT
MFR_VOUT_PEAK
MFR_VOUT_MIN
VOUT_SCALE_MONITOR
OT_FAULT_LIMIT
OT_WARN_LIMIT
READ_TEMPERATURE_1
MFR_TEMPERATURE_PEAK
READ_FAN_SPEED_1
FAN_COMMAND_1
MFR_FAN_FAULT_LIMIT
MFR_FAN_WARN_LIMIT
FAN_COMMAND_1
MFR_READ_FAN_PWM
MFR_FAN_FAULT_LIMIT
MFR_FAN_WARN_LIMIT
MFR_FAN_PWM_AVG
DIRECT Format Values
Interpreting Received
COMMANDS
R
R
- b)
UNITS
RPM
mV
NC
—
%
The following example demonstrates how the host can
send and retrieve values from the device. Table 4 shows
the coefficients used in the following parameters.
Table 4. Coefficients for DIRECT Format
Value
If the host received a value of 0D89h on a READ_VOUT
command, this is equivalent to:
All voltage-related parameters of PMBus devices are
reported as positive values. It is up to the system to know
that a particular output is negative if that is of interest to
the system. All output voltage-related commands use 2
data bytes.
COMMAND
X = (1/1) x (0D89h x 10
CODE
8Bh
RESOLUTION
1/32,767
0.01
0.01
1
1
READ_VOUT
COMMAND NAME
32,767
327.67
32,767
327.67
MAX
-(-0)
1
- 0) = 3465mV = 3.465V
32,767
m
1
1
1
1
m
1
b
0
0
0
0
0
b
0
R
0
0
2
0
2
R
0