MAS6505 datasheet(25/44 Pages) MAS

25 / 44 page

DA6505.005

11 June 2018

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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.

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.

Note that to select trim data from registers there

must be also set TRIM=01 or 10 in the Trim and

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.

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.

Table 10. Temperature and pressure offset trim register (FE/7EHEX) description

Bit

Number

Bit Name

Description

Value

Function

SGNOFST

Temperature Measurement Offset Sign

Positive

Negative

6-4

OFST

Temperature Measurement Offset

000

001

010

011

100

101

110

111

0% ISRADC

7% ISRADC

14% ISRADC

21% ISRADC

28% ISRADC

35% ISRADC

42% ISRADC

49% ISRADC

SGNOFSP

Pressure Measurement Offset Sign

Positive

Negative

2-0

OFSP

Pressure Measurement Offset

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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