DA6505.005
11 June 2018
TEMPERATURE AND PRESSURE OFFSET TRIM REGISTER (FE/7EHEX
)
Temperature and pressure offset trim register
(FE/7EHEX) is for configuring ADC input offset
settings for both temperature and pressure
measurements. There are eight offset options with
polarity available to match input signal range (ISR)
with different sensor signals. OFST and SGNOFST
bits are for the temperature offset and polarity
selection. Similarly OFSP and SGNOFSP are for the
pressure offset and polarity selection. See table 10.
test register (FA/7AHEX). After power up the
default setting is TRIM=00 which selects all trim
data from EEPROM.
The Temperature and pressure offset trim value
needs to be stored into Temperature and pressure
offset trim EEPROM address (BE/3EHEX) since by
default (TRIM=00) the trimming value is read from
the
EEPROM
before
every
temperature
measurement.
The input of the ratiometric ADC is differential with
input signal range of ISRADC = ±700mV =
1400mVpp at the nominal sensor supply voltage
VDDS=1.68V. The ADC offset options are in
7%*ISRADC steps which corresponds to absolute
input offset voltage step of 7%*1400mVpp=98mV.
See also chapters AFE AND ADC INPUT SIGNAL
RANGE DEFINITIONS and AFE GAIN AND ADC
OFFSET SELECTIONS which describes how the
GAIN and OFS settings define the sensor input
signal range and how to choose optimal values.
Note that to select trim data from registers there
must be also set TRIM=01 or 10 in the Trim and
Table 10. Temperature and pressure offset trim register (FE/7EHEX) description
Bit
Number
Bit Name
SGNOFST Temperature Measurement Offset Sign
OFST Temperature Measurement Offset
Description
Value
Function
7
0
1
Positive
Negative
6-4
000
001
010
011
100
101
110
111
0
0% ISRADC
7% ISRADC
14% ISRADC
21% ISRADC
28% ISRADC
35% ISRADC
42% ISRADC
49% ISRADC
Positive
3
SGNOFSP Pressure Measurement Offset Sign
OFSP Pressure Measurement Offset
1
Negative
2-0
000
001
010
011
100
101
110
111
0% ISRADC
7% ISRADC
14% ISRADC
21% ISRADC
28% ISRADC
35% ISRADC
42% ISRADC
49% ISRADC
Note: ISRADC=1400 mVpp (differential input signal range ±700 mV) at VDDS=1.68V
Note: Corresponding temperature measurement input signal offset voltage at sensor input is VOFST=(-1)SGNOFST*OFST/GAINT
Note: Corresponding pressure measurement input signal offset voltage at sensor input is VOFSP=(-1)SGNOFSP*OFSP/GAINP
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