Datasheet

LTC2974
48
2974fc
For more information www.linear.com/LTC2974
OT_FAULT_LIMIT, OT_WARN_LIMIT, UT_WARN_LIMIT and UT_FAULT_LIMIT
These commands provide supervising limits for temperature as measured by the external diode.
MFR_TEMP_1_GAIN and MFR_TEMP_1_OFFSET
The MFR_TEMP_1_GAIN command specifies the inverse of the temperature sensor ideality factor. The MFR_TEMP_1_
OFFSET allows an offset to be applied to the measured temperature.
Calculations using these paged commands are:
READ_TEMPERATURE_1 = T
EXT
• MFR_TEMP_1_GAIN – 273.15 + MFR_TEMP_1_OFFSET
Where:
T
EXT
= Measured external temperature in degrees Kelvin.
READ_TEMPERATURE_2 is substituted for READ_TEMPERATURE_1 if the associated T
SENSE
network fails to detect
a valid temperature. Under these conditions MFR_TEMP1_GAIN and MFR_TEMP1_OFFSET will have no effect. See
READ_TEMPERATURE_1 for more information.
MFR_TEMP_1_GAIN Data Contents
BIT(S) SYMBOL OPERATION
b[15:0] Mfr_temp_1_gain[15:0] 16-bit integer representing inverse of temperature non-ideality factor. Value = Y • 2
14
where Y = b[15:0] is an
unsigned integer. Example:
MFR_TEMP_1_GAIN = 1.0
For b[15:0] = 0x4000
Value = 16384 • 2
–14
= 1.0
pMbus coMManD DescripTion
EXTERNAL TEMPERATURE COMMANDS AND LIMITS
COMMAND NAME
CMD
CODE DESCRIPTION TYPE PAGED FORMAT UNITS EEPROM
DEFAULT
VALUE
REF
PAGE
OT_FAULT_LIMIT 0x4F Overtemperature fault limit setting for
the external temperature sensor.
R/W Word Y L11 °C Y 65.0
0xEA08
48
OT_WARN_LIMIT 0x51 Overtemperature warning limit for the
external temperature sensor
R/W Word Y L11 °C Y 60.0
0xE3C0
48
UT_WARN_LIMIT 0x52 Undertemperature warning limit for
the external temperature sensor.
R/W Word Y L11 °C Y 0
0x8000
48
UT_FAULT_LIMIT 0x53 Undertemperature fault limit for the
external temperature sensor.
R/W Word Y L11 °C Y –5.0
0xCD80
48
MFR_TEMP_1_GAIN 0xF8 Inverse of external diode temperature
non ideality factor. One LSB = 2
–14
.
R/W Word Y CF Y 1
0x4000
48
MFR_TEMP_1_OFFSET 0xF9 Offset value for the external
temperature.
R/W Word Y L11 °C Y 0
0x8000
48
MFR_T_SELF_HEAT 0xB8 Calculated temperature rise due to
self-heating of output current sense
device above value measured by
external temperature sensor.
R Word Y L11 °C NA
49
MFR_IOUT_CAL_GAIN_TAU_INV 0xB9 Inverse of time constant for Mfr_t_
self_heat changes scaled by 4 •
tCONV_SENSE.
R/W Word Y L11 Y 0.0
0x8000
49
MFR_IOUT_CAL_GAIN_THETA 0xBA Thermal resistance from inductor
core to point measured by external
temperature sensor.
R/W Word Y L11 °C/W Y 0.0
0x8000
49