DA6505.005

11 June 2018

23 (44)

configuring analog front end (AFE) gain (GAINP)

setting for the pressure measurement. There are 32

selectable gain options from 1x (0dB) to 55.8x

(34.9dB). The gain setting 1x bypasses the AFE and

connects the input signal directly to the ADC input.

See table 8.

The polarity of pressure measurement gain is

selected by additional sign bit (SGNGAINP).

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 Pressure gain trim value needs to be stored into

since by default (TRIM=00) the trimming value is

read from the EEPROM before every pressure

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.

Bit

Number

Bit Name

Description

Value

Function

7-6

-

-

X

-

5

SGNGAINP

Pressure Measurement Gain Sign

0

1

Positive

Negative

4-0

GAINP

Pressure Measurement Gain

00000

00001

00010

00011

00100

00101

00110

00111

01000

01001

01010

01011

01100

01101

01110

01111

10000

10001

10010

10011

10100

10101

10110

10111

11000

11001

11010

11011

11100

11101

11110

11111

1x (0dB), ISRP=1400mVpp

4.7x (13.4dB), ISRP=298mVpp

5.1x (14.2dB), ISRP=275mVpp

5.6x (15dB), ISRP=250mVpp

6x (15.6dB), ISRP=233mVpp

6.5x (16.3dB), ISRP=215mVpp

7.1x (17dB), ISRP=197mVpp

7.7x (17.7dB), ISRP=182mVpp

8.4x (18.5dB), ISRP=167mVpp

9.1x (19.2dB), ISRP=154mVpp

9.9x (19.9dB), ISRP=141mVpp

10.7x (20.6dB), ISRP=131mVpp

11.6x (21.3dB), ISRP=121mVpp

12.6x (22dB), ISRP=111mVpp

13.8x (22.8dB), ISRP=101mVpp

14.9x (23.5dB), ISRP=94mVpp

16.2x (24.2dB), ISRP=86.4mVpp

17.6x (24.9dB), ISRP=79.5mVpp

19.1x (25.6dB), ISRP=73.3mVpp

20.7x (26.3dB), ISRP=67.6mVpp

22.5x (27dB), ISRP=62.2mVpp

24.5x (27.8dB), ISRP=57.1mVpp

26.6x (28.5dB), ISRP=52.6mVpp

28.8x (29.2dB), ISRP=48.6mVpp

31.3x (29.9dB), ISRP=44.7mVpp

34x (30.6dB), ISRP=41.2mVpp

36.9x (31.3dB), ISRP=37.9mVpp

40.1x (32.1dB), ISRP=34.9mVpp

43.5x (32.8dB), ISRP=32.2mVpp

47.3x (33.5dB), ISRP=29.6mVpp

51.3x (34.2dB), ISRP=27.3mVpp

55.8x (34.9dB), ISRP=25.1mVpp

X = Don’t care

Note: Corresponding pressure measurement input signal range at sensor input is ISRP=ISRADC/GAINP=1400mVpp/GAINP @

VDDS=1.68V