Rainbow Electronics MAX34441 - Manual (Page 20)

PMBus 5-Channel Power-Supply Manager
and Intelligent Fan Controller
MAX34441
20
Interpreting Received
DIRECT Format Values
The host system uses the following equation to convert
the value received from the PMBus device—in this case,
the MAX34441—into a reading of volts, degrees Celsius,
or other units as appropriate:
X = (1/m) x (Y x 10- R - b)
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.
Sending a DIRECT Format Value
To send a value, the host must use the below equation
to solve for Y:
Y = (mX + b) x 10 R
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.
Table 3. PMBus Command Code Coefficients
PARAMETER COMMANDS UNITS RESOLUTION MAX m b R
Voltage
VOUT_MARGIN_HIGH
VOUT_MARGIN_LOW
VOUT_OV_FAULT_LIMIT
VOUT_OV_WARN_LIMIT
VOUT_UV_WARN_LIMIT
VOUT_UV_FAULT_LIMIT
POWER_GOOD_ON
POWER_GOOD_OFF
READ_VOUT
MFR_VOUT_PEAK
MFR_VOUT_MIN
mV 1 32,767 1 0 0
Voltage Scaling VOUT_SCALE_MONITOR — 1/32,767 1 32,767 0 0
Current
IOUT_OC_WARN_LIMIT
IOUT_OC_FAULT_LIMIT
READ_IOUT
MFR_IOUT_PEAK
mA 1 32,767 1 0 0
Current Scaling IOUT_CAL_GAIN mI 0.1 3276.7 1 0 1
Temperature
OT_FAULT_LIMIT
OT_WARN_LIMIT
READ_TEMPERATURE_1
MFR_TEMPERATURE_PEAK
N C 0.01 327.67 1 0 2
Fan Speed
READ_FAN_SPEED_1
FAN_COMMAND_1
MFR_FAN_FAULT_LIMIT
MFR_FAN_WARN_LIMIT
RPM 1 32,767 1 0 0
FAN_COMMAND_1
MFR_READ_FAN_PWM
MFR_FAN_FAULT_LIMIT
MFR_FAN_WARN_LIMIT
% 0.01 327.67 1 0 2
Timing
TON_DELAY
TON_MAX_FAULT_LIMIT
TOFF_DELAY
MFR_FAULT_RETRY
ms 1 32,767 1 0 0