NXP Semiconductors
FXPS7115D4
Digital absolute pressure sensor, 40 kPa to 115 kPa
Table 4.ꢀSelf-test control register
ST_CTRL[3]
ST_CTRL[2]
ST_CTRL[1]
ST_CTRL[0]
Function
SNS_DATAx
register contents
1
1
1
1
1
1
1
1
0
0
1
1
0
1
0
1
Digital self-test #1
Digital self-test #2
Digital self-test #3
Digital self-test #4
8171h
6C95h
807Ah
78ACh
7.3.2.3 Startup sense data fixed value verification
Four unique fixed values can be forced to the SNS_DATAX_x registers by writing to
the ST_CTRL bits as shown in Table 5. When any of these values are selected, the
ST_ACTIVE bit is set. These signals can only be selected when the ENDINIT bit is not
set.
Table 5.ꢀSelf-test control bits for sense data fixed value verification
ST_CTRL[3]
ST_CTRL[2]
ST_CTRL[1]
ST_CTRL[0]
Function
SNS_DATAx
register
contents
0
0
0
0
1
1
1
1
0
0
1
1
0
1
0
1
DSP write to SNS_DATAx_
X registers inhibited.
0000h
AAAAh
5555h
FFFFh
DSP write to SNS_DATAx_
X registers inhibited.
DSP write to SNS_DATAx_
X registers inhibited.
DSP write to SNS_DATAx_
X registers inhibited.
7.3.3 ΣΔ converter
A second order sigma delta modulator converts the voltage from the analog front end to a
data stream that is input to the DSP. A simplified block diagram is shown in Figure 5.
1 - bit
quantizer
transducer
first
integrator
second
integrator
V
X
α
1
=
C
C
TOP
C
INT1
α = 1
2
-1
z
-1
z
Y(Z) = {0,1}
BOT
-1
-1
1 - z
1 - z
C = C
TOP
- C
BOT
ADC
DAC
β
1
= 1
β = 1
2
V = +V
, 0 V, -V
REF
REF
V = C x V /C
INT1
x
aaa-023446
Figure 5.ꢀΣΔ converter block diagram
The sigma delta modulator operates at a frequency of 1 MHz, with the transfer function in
Equation 1.
(1)
FXPS7115D4
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© NXP B.V. 2019. All rights reserved.
Product data sheet
Rev. 3 — 5 December 2019
8 / 72
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