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Ext_temp_cal (max15301aa01), Ext_temp_cal (max15301aa02) – Maxim Integrated MAX15301 PMBus Command Set User Manual

Page 35

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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