iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
Rev B1, Page 21/24
TEMPERATURE COMPENSATION
TEMP
Adr 0x01; Bit 0
Function
R/W
Temperature compensation is enabled by setting con-
trol bit TEMP of register 0x01. A piece-wise linear in-
terpolation of values stored in a look-up-table (LUT) is
employed to calculate the gain and offset for a given
temperature. Figure 6 shows a sample configuration
with seven breakpoints.
Code
0
1
Temperature compensation is disabled (default)
Temperature compensation is enabled
Table 41: Temperature compensation enable
gain/ofs
ofsZ
ofsB
ofsA
gainB
gainA
ADC value
bp0
0
bp1
bp2
bp3
bp4
bp5
bp6
255
Figure 6: LUT with seven breakpoints
There can be a minimum of two up to a maximum the last valid LUT entry. All addresses thereafter in-
of 16 temperature breakpoints within the LUT. Each cluding their data will be ignored.
breakpoint has five interpolation values associated to it
namely GAINA, GAINB, OFSA, OFSB and OFSZ. For Temperature dependent gain and offset is determined
more details on the layout of the LUT refer to section by performing linear interpolation between break-
"EEPROM" on page 11.
points. Temperature dependent gain and offset are
TGAINA/B and TOFSA/B respectively.
Breakpoints can be placed freely across the temper-
ature axis except for the first and the last breakpoint. Fine gain FGAINA/B and fine offset FOFSA/B (see fig-
The first breakpoint must be located at ADC value 0 ure 4 on page 14) are calculated as follows:
(which roughly corresponds to -50 °C when using the
internal sensor), the last breakpoint must be located at
ADC value 255 (150 °C with the internal sensor).
fgain = tgain +dgain
fofs = tofs +dofs
The LUT is stored in the off-chip EEPROM from mem-
ory location 0x10 onward. Note that the EEPROM ad-
dress space maps to the 1-wire address 128. Access-
ing EEPROM address 0 is therefore equivalent to ac-
cessing memory location 128 through the 1-wire inter-
face. The breakpoint entry with a value of 255 marks
Whereas TGAIN and TOFS are the temperature de-
pendent values calculated using the LUT and DGAIN
and DOFS are registers updated either manually or by
the automatic compensation function.
ICHAUS [ IC-HAUS GMBH ]
