Maxim Integrated MAX15301 PMBus Command Set - Manual (Page 35)

MAX15301 PMBus Command Set User’s Guide
Rev 1 Page 35 of 53
EXT_TEMP_CAL (MAX15301AA01)
Byte
#
Data Byte
Name Units Description
0
Ideality Factor
and Gain Correction
None
Combined diode ideality factor and external temperature
gain correction scalar
1 Offset correction °K External temperature measurement offset correction
The corrections are applied internal to the MAX15301 as follows:
READ_TEMPERATURE_2 = (Measured external temperature) / EXT_TEMP_CAL[0] + EXT_TEMP_CAL[1] - 273.15°K
EXT_TEMP_CAL (MAX15301AA02)
Reference: Maxim Specific Lockable: Yes
Command Code: 0xF8 Format: Linear
Data Bytes: 4 Units: Scalar, °K
Transfer: Read/Write Block Factory Value: 1.00391, -8°K
Description/Notes: The EXT_TEMP_CAL command allows calibration of the external temperature sense signal. The two
arguments of the EXT_TEMP_CAL signal are as follows:
Data Byte
Number
Data Byte
Name Units Description
0 m None
Combined temperature gain correction and diode ideality
factor
1 b °K Temperature offset correction
Temperature Calibration
The default gain term is nominally set for use with a Fairchild MMBT3904 transistor diode junction. To
correct the gain term for a different temperature sense transistor, do the following:
1. Read the existing value of EXT_TEMP_CAL from the device
2. Multiply the existing value of the gain correction term by the new transistor ideality factor
3. Divide the result by 1.0046
Send the final result back to the device