DA6505.005
11 June 2018
PRESSURE GAIN TRIM REGISTER (FC/7CHEX
)
Pressure gain trim register (FC/7CHEX) is for
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.
default setting is TRIM=00 which selects all trim
data from EEPROM.
The Pressure gain trim value needs to be stored into
Pressure gain trim EEPROM address (BC/3CHEX
)
since by default (TRIM=00) the trimming value is
read from the EEPROM before every pressure
measurement.
The polarity of pressure measurement gain is
selected by additional sign bit (SGNGAINP).
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
test register (FA/7AHEX). After power up the
Table 8. Pressure gain trim register (FC/7CHEX) description
Bit
Bit Name
Description
Value
Function
Number
7-6
-
-
X
-
5
SGNGAINP Pressure Measurement Gain Sign
GAINP Pressure Measurement Gain
0
1
Positive
Negative
1x (0dB), ISRP=1400mVpp
4-0
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
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
23 (44)
MAS [ MICRO ANALOG SYSTEMS ]
