Analog Devices EVAL-ADuCM355QSPZ, Руководство пользователя

Страница: 16 / 24

UG-1308 EVAL-ADuCM355QSPZ Evaluation Board
Rev. A | Page 16 of 24
4-LEAD ELECTROCHEMICAL SENSOR EXAMPLE
Many electrochemical sensors come in 4-lead packages that have a
counter, a reference, and two sensing electrodes. The
ADuCM355
supports biasing and measuring of these sensor types.
The M355_ECSns_DualWE example project configures the
low power, potentiostat CH0 channel to bias the sensor. The
current flowing to and from the SE0 pin is measured via the
low power TIA Channel 0 (TIA0). The current flowing from
the SE1 electrode is measured via the low power TIA Channel 1
(TIA1).
The TIA amplifiers convert the current to a voltage that is
measured via the analog-to-digital converter (ADC), and the
source code calculates the current flowing in each electrode.
The
M355_ECSns_DualWE
code example project is located in
the examples folder.
Figure 30 shows the configurable parameters located in the
AD5940Main.c
file. Modify the value of the correct
LpTiaRtiaSel parameter for each channel based on the
maximum expected current.
Figure 31 shows the connection details between the 4-lead
sensor and the
ADuCM355 .
16
88
7
-23
1
Figure 30. Dual Working Electrode Configuration
VBIAS0
VBIAS
SW12
PA
ADC
MUX
LPTIA0
LPTIA1
SW0
SW14
SW2
SW3
RE0 RE0
CE0
CE0
SE1
CAP_POT0
100nF
SW13
VZERO0
VZERO
VZERO
LPDAC0
VZERO TO INPUT
R
TIA
R
LOAD
R
F
AIN7_LPF1 AIN4_LPF0
168
87-
136
SE0
SE0
SE1
SW0
R
TIA
R
LOAD
R
F
Figure 31. Circuit Setup for 4-Lead, Dual Gas Detection Sensor