The Engineering Mind
3D ToF Depth Sensing
Clock and Timing
Design Tools and Calculators
Direct Digital Synthesis (DDS)
Embedded Vision Sensing
Energy Monitoring and Metering
FPGA Reference Designs
Interface and Isolation
Low Power RF Transceivers
MEMS Inertial Sensors
Motor Control Hardware Platforms
Power By Linear
Processors and DSP
RF and Microwave
Wireless Sensor Networks Reference Library
AFE Transmit Stage
Precision Microcontrollers requires membership for participation - click to join
4Wire-Isolated-Bioimpedance ADuCM350 Connections To Sensor
ADUCM350 DESIGN SUPPORT COMMUNITY - INTRO
ADuCM350 FAQ ADuCM350 Evaluation Kit
ADuCM350 FAQ AFE / ADC Measurement Channel
ADuCM350 FAQ AFE Measurement Circuit Impedance Range
ADuCM350 FAQ AFE Sequencer
ADuCM350 FAQ AFE TIA
ADuCM350 FAQ Amperometric Measurement Example
ADuCM350 FAQ Calibrate
ADuCM350 FAQ CRC accelerator
ADuCM350 FAQ Debug
ADuCM350 FAQ DFT / Impedance Measurement
ADuCM350 FAQ Evaluation Kit Software Platform
ADuCM350 FAQ GP Timers
ADuCM350 FAQ GPIOs and Pinmuxing
ADuCM350 FAQ I2C serial interface
ADuCM350 FAQ Index
ADuCM350 FAQ LCD controller
ADuCM350 FAQ Operational Supply Range / Power Supplies
ADuCM350 FAQ Parallel Display Interface(PDI)
ADuCM350 FAQ Potentiostat / Amperometric
ADuCM350 FAQ Power Consumption
ADuCM350 FAQ Power Management Unit
ADuCM350 FAQ Random Number Generator
ADuCM350 FAQ Real Time Clock (RTC)
ADuCM350 FAQ SDK Driver Specific FAQs
ADuCM350 FAQ SPI
ADuCM350 FAQ Switch Matrix
ADuCM350 FAQ System Clocks
ADuCM350 FAQ System Integrity
ADuCM350 SDK v18.104.22.168 now available
ADuCM360 offset voltage
ADuCM360 programming in production
ADuCM360 VDAC interpolation mode
ADuCM360, CRC-24 initial values
ADUCM360/361 ADC input or external reference short/open detection
ADUCM360/361: ADC ENOB Calculation
ADUCM360/361: Configuring unused ADC inputs
ADUCM360/361: Convert ADC reading to voltage
ADUCM360/361: Differences between Serial Wire Debug and JTAG
ADUCM360/361: Memory-to-Memory DMA transfers
ADUCM360/361: Register Information
ADUCM360/361: SINC3 and SINC4 digital filter performance vs different ADC sampling rates
ADUCM360/ADUCM361: External Clock
ADuCM361 serial download mode
AFE Transmit Stage
Bio-Impedance & ECG Measurement Solution
Bioimpedance Measurement Using ADuCM350
CN0300: Calibration Options
CN0300: DAC output settling time
CN0300: Increasing DAC Resolution
CN0300: Is it possible to use the ADuCM361 instead of the ADuCM360?
CN0300: Maximum Loop Voltage (AIN8 connected to INT_Vref)
CN0300: Power Consumption
CN0300: Type-K or Type-J thermocouple instead of Type-T
Continuously Amperometric Measurement Example
Difference between ADuCM360 and ADuCM361
downloading issue with MDIOWSD v0.1 and aducm320
Errata for ADuCM350 I2C serial interface
Example for parity checking on ADuCM361
FAQ ADuCM350 Embedded Software Development
FAQ for Captouch on ADuCM350
FAQ: ADuCM360 - IAR Embedded Workbench
FAQ: ADuCRF101 antenna information
FAQ: Getting Started with the ADuCRF101 Development System
FAQ: How to order the ADuCRF101 Development System
FAQ: How to use the ADuCRF101 Serial Downloader
FAQ: The ADI Elves Software Tool
First Steps: Quick Measurement with Eval-ADuCM350 & EKSP Labview GUI
How to get SDK + Eval-ADuCM350EBZ Working together.
How to use ADICUP360 with EmBitz
Issues with USB-SWD/UART-EMUZ
Known Issues for ADuCM350 Silicon and Support Material
New Revision of UG-587 Available
Optimizing RCAL,RTIA,CTIA and DAC voltage of ADuCM350 for 4-Wire Measurement.
Potentiostat / Amperometric Measurement Using ADuCM350
Precision Microcontrollers Space Description
Support for Analog Microcontrollers in Keil MDK-ARM Microcontroller Development Kit v5.xx
Unipolar Current Measurement Using ADuCM350
Video: Wireless Energy Metering Communications System from Analog Devices
AFE Transmit Stage
How does the ADuCM350 set a voltage on the sensor ?
First step is to consider the DAC and it's transfer function.
The VDAC Output Range is 0.2V to 1.0V.
This signal is then biased and gain up to produce the output voltage from the Excitation Amplifier, VD, which is the voltage seen by the sensor.
VD = ( ( VD-0.6V ) X 2 ) + VBIAS
VDAC is referenced to the INAMP reference of 0.6V
The Excitation/INAMP Loop has a gain of 2.
VBIAS: The Common Mode of the System is setup by the +ve terminal of the TIA.
This leads to a transmit channel transfer function that looks like:
How does the TIA set the Common Mode of the AFE Measurement Loop ?
See diagram below as reference.
Assume 2-Wire Measurement with P and N tied internally.
In 4-Wire, Raccess would be automatically compensated for on D/P/N and T.
TIA Sets Common Mode
Positive terminal of the TIA is connected to VBIAS.
Therefore the negative terminal of TIA forced to VBIAS.
This is a Virtual Ground.
T = N = VBIAS
T and N are shorted internally
Excitation Buffer Forces D so that P – N = 0V
But N is forced to VBIAS by TIA
So Excitation Buffer drives P to = VBIAS
Hence D is forced to have a common mode of VBIAS
With the DAC at midscale, the Excitation Buffer
output sits at VBIAS
Example Calculation: Sensor needs to see +450mV on Counter and 0V on Working Electrode. i.e +450mV step across Sensor.
Goal is to have P – N = +450mV
Assume VBIAS = 1.1V.
T = 1.1V = Virtual Ground
Given that N = T = VBIAS, this implies that the voltage at the P node needs to be 1.55V
Signal swing of Excitation Amplifier output is -800mV to +800mV
Dividing this range by the resolution of the DAC
1.6V / 2^12 = 390.725µV
Therefore each DAC LSB is equivalent to 390.725µV out of the Excitation Amplifier
Midscale of the DAC is equivalent to a 0V difference between P and N
Midscale DAC code = 2048 = 0x800
450mV / 390.725µV = 1152 = 0x480
1,1V + 450mV = 0x800 + 0X480 = 0xC80
Therefore, the DAC code required for a +450mV step on the sensor is 0xC80
dac transmit channel
Privacy & Security Statement
Accept & Continue